The Iron Age 1944-07-13: Vol 154 Iss 2

Vice-President Seneral Vol. 154, No. 13, 1944 Editorial and Advertising Offices Editorial shen the Hayes, Production The Hippocratic Oath for Engineers on, with Bour, Typography and Layout Regional Business Managers Technical Articles bottom) arbide Offset Tools with Composite ping and Los Angeles Electroplaters Discuss Industrial Finishing Pre-Fill Injection System For Die Castings.............. veakened Owned and Published CHILTON COMPANY (Incorporated) eatures Executive Offices EORGE GRIFFITHS BAUR Vice-President HARRY DUFFY CHARLES News and Markets Attention Gray Iron Foundry Problems Foundries Given Manpower Member, Audit Bureau Circulations Solution Sought for Steel Non-Ferrous Metals News and Developments 146 Non-Ferrous Metals Prices; Scrap 148 Iron and Steel Scrap News and every script i-Fini Possessions, $8; Foreign, $15 Steel Pipe and Tubing 158 Single Copy, cents. Pig Iron and Coke Prices................. Railroad Material and Stainless Steel Prices. 161 ° Ferroalloy Prices 162 ° | j CALL THE PLANT NEAREST YOU CHICAGO........ 16th and Rockwell Sts. Rockwell 2121 320 So. 19th St. Mitchell 7000 1600 Euclid Ave. Madison 3860 Central 1020 CINCINNATI. Front St. and Freeman Ave. Cherry 3232 53rd and Lakeside Ave. Henderson 1000 330 Grant St. Walnut 7540; Carnegie 795 5200 Grays Ave. Bell-Belgrade 1412; Keystone-West 1644 Humboldt 3311 NEW YORK....,......203 Westside Ave. City, New York 2-3700 Newark...............Market 2-6067 City............Bergen 4-1123 BOSTON. Binney Sts., Cambridge Kirkland 6000 JOSEPH RYERSON SON, INC. quick steel Call Ryerson RYERSON Over 10,000 kinds, shapes and J 4 IRON ESTABLISHED ° ° July 13, 1944 ° President and Editorial Director BAUR Vice-President and General Manager ° ° DIX Manager, Reader Service ° ° Editorial Staff Technical Editor......F. OLIVER Commercial Editor, CAMPBELL Associate Editors WINTERS BARMASEL Editorial Assistants SCHIEN WILLIAMS ROGERS News and Technical Editors LLOYD Pittsburgh 428 Park Bidg. POST Chicago Otis Bldg. MOFFETT DONALD EUGENE HARDY Washington National Press MacDONALD Cleveland 1016 Guardian BRAMS Detroit 7310 Woodward Ave. OSGOOD MURDOCK San Francisco 1355 Market St. Editorial Correspondents ROBERT Cincinnati PENLEY Buffalo FRAZAR Boston HUGH SHARP Milwaukee SANDERSON Toronto, Ont. RAYMOND KAY Los Angeles JOHN McCUNE Birmingham ROY EDMONDS St. Louis JAMES DOUGLAS Seattle The Hippocratic Oath For Engineers and surgeons will come out this war not only with clear consciences but with the heartfelt thanks humanity re- gardless race party. They have exerted themselves the utmost save human life. Engineers, the other hand, will not able have this said them. They have done wonderful job helping destroy human life. Think what war would today without airplanes, rocket guns, tanks, submarines and the countless other instruments produced engineering genius. realize that inviting some very caustic comments from engineering friends making this statement. They will write and ask would prefer have them hold back and permit the Axis powers forward with their destruction engineering and thus become rulers the world. And will have admit that would not. want see this war won and when is, will be, large part the credit for winning will the engineers and designers our fraternity. But want see stay won and think that engineers and designers should have voice this too and not have left the politicians after and the armed forces the Allies have done the necessary killing and maiming. Personally, all the engineers whom have ever met, whatever nationality, are peaceable people who like solve problems rather than invent problems that will hurt others who may have solve them. never knew engineer who wanted kill anyone, even though that person might have been professor who flunked him physics mathematics. Most engineers, sure, when they invent some new machine have mind make things easier and not harder for people. This war the last chance for humanity and for the engineers who are part it. For unless, after win the war, make impossible for anyone ever again practice destruction engineering, none will have die hell. The robot flying bomb makes that perfectly clear. has come too late save the Axis but give any capable group engineers ten fifteen years more develop and perfect and there will not city anywhere earth whose inhabitants will not have cause live daily and nightly fear annihilation explosions, fires poison gas. If, demonstrated the Germans, you can successfully fly one ton bomb for sixty miles, inevitably follows that improvement and development will enable you fly fifty ton bomb not merely hundred miles but perhaps thousand. And then where are you? These implements destruction could not made politicians. They are made possible engineers and technicians. Even the airplane was first conceived and developed instrument for war. That’s heavy responsibility our shoulders. Doctors and surgeons take the oath Hippocrates before they start practice and live afterwards. They swear that they will use their knowledge and skill save human life and not destroy it. engineers throughout the world would agree take the same oath, there would more war. RED (Courtesy Food Machinery Corp.) Buffalos That Roam Land and age the extreme western end Makin Island, the surf was too high for successful landing operations—so the Japs thought. They heavily guarded small opening the reef, where there was little surf. But the Allied forces, using amphibian tanks plunged through the high breakers, passed over the reef, crossed the lagoon and soon wiped out superior Jap force. These amphibian tanks, known are built the Food Machinery Corpo- ration, and into them many tons steel supplied Inland. They are hard hitting tanks, equally home land the water, that are making island hopping history the Southwest Pacific. Thousands upon thousands tons steel from Inland now are being used build many types fighting equipment —ships, tanks, guns, bombs, trucks, that are used wherever men fight for freedom. Tomorrow, when Victory ours, Inland will again supply steel for America’s peacetime needs. invite your inquiries. INLAND STEEL COMPANY Dearborn St., Chicago Illinois Branch Offices: Cincinnati Detroit Kansas City They have helped solve the probl landing vey have helped solve the problem landing troops enemy-held f definitely sight. News Although WPB announced fortnight ago that experimental model production and tooling for civilian automobile requirements would authorized, orders have yet come through. General expectation that these orders will first released when the automobile company presidents hold their second reconversion conference with July 14. WPB will not permit production start until Germany falls, until the fall Detroit generally the opinion that that position will reached the end the year. American bombers are delivering more than 2,500,000 propaganda newspapers and leaflets daily the people Germany and occupied Europe. First traces decreasing war production are evidence Cleveland. War plants are increasingly prone observe all vacations and lay off men when any t contract hitch occurs. d beach and SAE 4640. Highway construction must doubled after the war, according the American Road Builders' Association. Die-casting machines the prefill injection type are being increasingly The equipment virtually eliminates porosity castings size fore considered beyond the range commercial Boron may substituted for nickel, molybdenum chromium the forging steels The substitution gives better hardenability, and equal impact and machinability properties. Band instruments are now being made regular commercial quantities electro- The technique differs radically from ordinary plating practice and calls for the last word control equipment. new bright alloy plate consisting ternary deposits copper, tin and zinc, has been made available commercially. The alloy bright deposited, hard, has good tarnish resistance, non-magnetic and has high protective value over copper copper alloys. recommended replace nickel plate. Builders the West, Inc., organization pledged the development the West. can assure base price finished iron and steel Los Angeles, San Francisco, Portland and Seattle within the most ton Pittsburgh, Chicago, Birmingham and Baltimore, West Coast manufacturers will consider its mission accomplished. Captured German oil and gasoline, being based synthetic processes, are ingly different from types, but are still very high quality. Germans ally blend tetraethyl lead, benzol and alcohol gasoline base stocks the field. The Allies ship their fuel already blended. About 7,000,000 lb. aluminum being released the for food cans and containers, substitute for tinplate. The latter has tight supply San Francisco Chamber Commerce states that the average weekly earnings workers that area $59.53, for 45.1 hr. work. Manpower shortage the Pacific Coast increasingly severe, yards and other war plants falling behind production schedules. Maritime Commission states that Pacific Coast shipyards will loaded with éven heavier orders that will maintain peak production through 1945. The trend prime contractors drawing former sub-contract work into their own Shops thus cutting out some the smaller companies concerning the WPB and the armed forces. This trend inclined cause some unemployment where labor generally eaSier and tightening the labor demand prime contract areas Where labor mostly acute. Machine tool builders have keenly felt the loss the draft men under 26. THES the age group where greatest initiative and versatility are found, industry explain. fact, much the credit for the machine tool industry's recent building years' normal production tools about three years goes these younger men. resulting 1944 4 ig > - Boron 9440 and HIS work was planned a.con- tinuation the comparisons various Bortam Carbortam treated steels with similar steels con- taining molybdenum extra man- Tue Sept. 1943, 48; and Metals and Alloys, May, 1943, 978. instead boron, that were previously published the writer*. The object the present work was extend similar comparison boron with other alloys, nickel and chro- mium some the modern and widely used low alloy forging steel. Thus the 9440 steel, stand- ard composition was compared with Carbortam treated steels which lacked either part the manganese, most the chromium, the nickel and molybdenum; and the SAE 4640 steel, standard compositions with low and high nickel respectively were com- pared with Carbortam treated steels without either most the nickel most the molybdenum. Tensile and impact tests were made forged bars these steels quenched oil and tempered various temperatures from 600 deg. 1200 deg. F.; and Jominy hardenability tests and few machinability tests were also made. the 9440 steel, Carbortam treatment giving only 0.0022 per cent residual boron did not maintain the hardenability when the manganese was reduced 0.57 per cent and the molybdenum 0.02 per cent. Car- bortam treatment giving 0.003 0.004 per cent residual boron did maintain the same higher harden- ability, however, when chromium was omitted, when nickel and molybde- num were both omitted, except for the residual contents obtained from scrap. the SAE 4640 steel, the same Car- bortam treatment gave equal better hardenability than 1.20 per cent nickel 0.25 per cent molybdenum. The re- placement value for chromium seems from this work about 0.6 per cent, instead 0.35 per cent was previously suggested. The tensile and impact properties oil quenched and tempered speci- mens are approximately the same, whether Carbortam the other al- loys are used; but the tempering tem- 48—THE IRON AGE, July 13, 1944 perature may require adjustment, especially when molybdenum omit- ted, since molybdenum steels are not tempered readily other alloy steels. Machinability tests also show difference. There considerable economy using Carbortam instead nickel, molybdenum, chromium these heat treated forging steels, equivalent properties being obtainable saving about $5.25 per ton steel when the made for nickel, per ton the case molybdenum, and about $1.50 for chromium. The same benefits ten- sile, impact, and machining properties that are found when the boron alloy treatment substituted for higher managanese are not found, however, when the substitution made for nickel chromium. Materials Used The steels used this investigation were melted basic lined in- duction furnace using low carbon wire rods the chief melting stock. This stock was found contain about 0.12 per cent nickel, 0.09 chromium, and 0.01 per cent molybdenum. All the heats contained 0.39 0.42 per cent 0.20 per cent silicon, 0.025 0.037 per cent sulphur, and about 0.018 per cent phosphorus, Boron was used only the form Carbortam, all the treated steels re- ceiving addition lb. per ton, about 0.08 per cent titanium and 0.005 per cent boron. these steels 1.25 lb. aluminum per ton was added before the Carbortam, and all the other steels were deoxidized with 1.5 aluminum per ton. Their analyses are given Table The 2.5 3-in. square ingots were heated 2000 deg. about 2.5 hr. and held that temperature for hr. before forging. They were forged rather slowly, with several periods reheating, %-in. round bars, fin- ishing bright red heat. These distribution along sides quenched specimens. =x | + SAE 4640 Steels + + > oO oO Rockwell hardness ~ Distance from quenched end, inches wire This 0.12 and \ll the cent silicon, and orm els re- ton, and steels added ith nalyses were out 2.5 ire for forged iods rs, fin- These along end- SAE 4640 Steel bars were cut with hacksaw into suitable lengths for the test speci- mens, and all them were normal- ized hr. 1650 deg. before ma- chining. Hardenability Tests These tests were made the Jominy end-quench method, using specimens machined in. diam- eter and heated for hr. 1550 deg. before quenching. extra speci- men Steel No. was quenched from 1600 deg. The Rockwell hard- ness was determined duplicate flat strips ground carefully along the sides the quenched specimens the usual way, and average values are shown plotted against the distance from the quenched end Fig. The hardenability Steel No. was found very low, compared with the other steels, and further work was done this heat. The boron recovery was lower than ° COMSTOCK Metallurgist, Titanium Alloy Mfg. Co., Niagara Falls Considerable economy possible the substitution boron for nickel, molybdenum chromium the heat treated forging steels, 9440 and SAE 4640. The substitution gives equal better hardenability; and tensile, impact machinability properties show difference. Tempering temperature may require some adjust- ment, especially when molybdenum omitted. the others, and evidently the 0.002 per cent boron retained the steel was not sufficient compensate for the lower hardenability resulting from the deficiency 0.57 per cent manganese and 0.02 per cent molyb- denum compared with the non-boron steel No. Since sufficient data com- paring the relative effects man- ganese and boron seemed avail- able from the THE IRON AGE article,* was not thought necessary make this heat over again for the present work. The other hardenability curves for the 9440 steels Fig. show Elongation 2in.,per cent more gradual slope for the No. steel characteristic molybdenum and steeper drop for the others, charac- teristic boron. Steel No. with boron, nickel and molybdenum, shows the highest hardenability, though steel No. with boron and higher chro- mium than No. though without nickel and molybdenum, very slose second. Steels Nos. and with boron and lower chromium, gave curves placed might expected from their chromium and manganese contents. The Carbortam treatment the 9440 steel thus seen about equivalent, its effect hardenability, about 0.43 per cent nickel plus 0.13 per cent molybdenum, but exceed considerably the effect 0.38 per cent chromium (compar- ing steel No. with No. 1). Also, com- paring the Carbortam treated steels Nos. and appears that the hardenability effect 0.58 per cent chromium about the same that 0.36 per cent nickel plus 0.10 per cent molybdenum. Therefore, the Car- bortam effect seems equivalent much more than 0.35 per cent chro- mium was estimated Crafts and quoted the writer’s IRON AGE ar- ticle.* The present comparisons with nickel and molybdenum, however, seem fair agreement with previous estimations. the SAE 4640 steel, compari- son the hardenability curves for Nos. and shows that the Carbor- tam treatment gave very slightly greater hardenability than 1.19 per extra nickel, which agrees well with the previous estimation for nickel quoted the IRON AGE ar- ticle. Comparison the curves for steels Nos. and indicates much greater hardenability from the Carbor- tam treatment than with 0.23 per cent extra molybdenum, which not very good agreement with the writer’s THE IRON AGE, July 13, ° ° ° 240,000 ° empering temperature, deg.F. at previous work. This probably due the fact that this boron treated steel No. was not entirely free from molybdenum, and may, therefore, considered additional support the claim that the boron alloy treat- ment least effective about 0.25 per cent molybdenum. should noted however that both the 9440 and the SAE 4640 series, the molybdenum steels (except for No. gave hardenability curves that were definitely above those for most the other steels their lower portions, with the slower cooling rates. This distinctive effect molybdenum was noted previously the Metals and Alloys article.* No. here, with high chromium, however, seems in- dicate that chromium above about 0.55 per cent may have the same effect smaller molybdenum contents the hardness the slowly cooled parts the Jominy test bar. Tensile Tests The normalized specimens for ten- sile testing were machined about 0.52 in. diameter for in. gage length, heated 1550 deg. for hr. and quenched oil. Separate specimens were tempered hr. 600 deg., 750 deg., 900 deg., 1050 deg., and 1200 deg. respectively, and then finished about 0.500 in. diameter grinding. The bars were pulled TABLE Chemical Analyses the Steels Used 9440 Steel Carbortam Yes Yes Yes Yes Yes 0.41 0.41 0.42 0.41 0.41 1.04 0.47 1.07 0.87 0.95 0.96 0.25 0.24 0.26 0.33 0.31 0.28 0.47 0.46 0.09 0.24 0.53 0.67 0.0022 0.0040 0.0032 0.0040 SAE 4640 Steel Carbortam Yes Yes 0.40 0.41 0.40 0.40 0.68 0.71 0.63 0.64 0.20 0.23 0.23 0.26 1.56 1.79 0.60 1.54 0.30 0.23 0.25 0.07 0.018 0.016 0.054 0.036 0.0004 0.0012 0.0032 0.0034 TABLE Results Sawing and Hardness Tests Manganese Steels Tempering Steel No. Analysis, Per Cent Temperature, Time, Referring Deg. F., Seconds for Average THE IRON AGE, After Oil Sawing Rockwell 0.28 1.23 0.0038 900 28.7 10M 0.40 900 164 30.5 12M 0.40 1.12 0.0042 900 29.8 10M 930 158 28.7 12M 0.40 1.12 870 28.9 0.36 1.26 0.0015 900 23.8 IRON AGE, July 13, 1944 slowly, the usual way, the yield points being recorded the drop-of- the-beam, which was well marked the bars tempered the lower tem- peratures, and was checked with strain gage the other specimens. The results are reported Figs. and except for the yield points which are Figs. and These curves show the variation the ten- sile properties with tempering tem- perature for each steel, the 9440 steels appearing Figs. and and the SAE 4640 steels Figs. and Among the 9440 steels, No. the regular steel without Carbortam treatment, shows general about the highest tensile strength and point, with fair ductility. The high chromium steel No. where Carbor- tam replaced nickel and molybdenum, approaches No. most closely strength, but deficient ductility, especially reduction area the lower tempering temperatures. No. the similar steel with low chromium, shows the best ductility, but the low- est strength. The other Carbortam treated steels, No. without chromium and No. without nickel molybde- num, are hardly any better than No. ductility and general slightly below No. strength. There does not seem much difference, tensile properties after tempering, between fully hardened 9440 steel and similar steel with Carbortam treatment substituted for either the chromium, the nickel and molybde- num. the SAE 4640 steels included this research, the situation some- what different. The two untreated steels Nos. and were about equal strength, the differences nickel and molybdenum apparently balanc- ing each other, but No. with higher nickel and lower molybdenum shows some superiority ductility. No. the Carbortam treated steel with low nickel, practically equivalent No. both strength and ductility. No. 10, the Carbortam treated steel with low molybdenum, shows superior ductility, though generally lower strength except after the 600 deg. tempering. This supports very well the comparison reported the Metals and Alloys article,* where was found that with boron alloy treated steel lower tempering temperature has used for given strength than with molybdenum steel otherwise similar composition, but even the ductility will better, with the same strength, the boron alloy treated steel. Impact Tests The normalized impact test speci- mens which were prepared for tem- yield p-of- tem- oints ten- tem- 9440 and rtam the high rbor- num, ility, the low- rtam does ring, steel ‘tam the ated qual ickel anc- low steel rior well was ated ture ngth but tter, pering 600 deg. 750 deg. were finished 0.394 in. square and notched with three standard Izod V-notches pefore hardening oil from 1550 deg. The notches were protected refractory coating from scaling when the specimens were heated for quenching. The specimens intended for tempering 900 deg. above were rough machined about 0.42 in. square before quenching oil from 1550 deg. F., and finished 0.394 in. square and notched after tempering. The Rockwell hardness was deter- mined the sides the finished specimens between the notches. The impact tests were made the usual way with 200 ft.-lb. blow room temperature, and the results are plot- ted Figs. and each point being the average value from three tests. The hardness values are also plotted the same charts. Fig. the Carbortam treated steels are seen generally su- perior impact resistance the reg- ular 9440 steel No. except after tempering the highest temperature, 1200 deg. The No. steel was harder, however, after each tempering treatment. The low chromium steel No. which had the lowest strength, showed the best impact values after most the tempering treatments. The Carbortam treated steel No. with- nickel molybdenum, was tougher than No. after all temper- ing treatments except 1200 F., and No. without chromium, was better after all treatments except 1050 deg. and especially superior after tem- pering the lower temperatures. The hardness values the impact speci- mens are roughly inverse relation the impact values. Fig. the impact value and hardness curves the SAE 640 steels show, like the tensile test curves, closely similar results for the two non-boron steels Nos. and No. the Carbortam treated steel with low nickel, was very slightly tougher after tempering 750 deg. 900 deg. F., though softer; but was not quite tough the non-boron steels, well softer, after tempering the higher temperatures. No. 10, the Car- bortam treated steel with low molyb- denum, was quite definitely superior toughness the other steels well softer, after all the tempering treatments. This agrees well with the tensile results. Machinability Tests Two kinds machining tests were made these steels, one involving the measurement the time required for removing definite quantity metal lathe, and the other the time re- quired for cutting section with mechanical hacksaw. The former was applied the normalized hardenabil- ity test specimens, using small lab- oratory lathe. The specimens were first rough turned in. diameter remove the scale and decarburized surface, and then ten cuts about 0.01 in. depth were taken for length in. each specimen, reducing the diameter somewhat more than in. the difficulty cutting in- creases, this lathe slows down, the cumulative time for the ten cuts, which was measured, should correlate with the machinability. The same tool was used for all the work and the edge was rubbed fine carborun- dum block, but not ground, between specimens. The results are reported the sixth column Table II. The saw-cutting tests were made the larger ends tensile test stubs. Stubs specimens tempered 900 deg. and 1200 deg. were test- without further treatment, while those tempered 1050 deg. were normalized again 1650 deg. order get some results the nor- malized steels the saw-cutting method. Three four cuts were made across the in. diameter specimen with constant weight the blade the mechanical hacksaw machine, and the time for each cut was re- corded. lubricant coolant was used, but the specimens were cooled between consecutive cuts. new saw blade was used for each series specimens; the first cut was made each steel the series turn, then the second cuts each one the same order, and on. The results for the first cuts were discarded all but one series, because the cutting TABLE Results Machinability and Hardness Tests Analysis, Per Cent Steel 9440 0.47 0.55 0.14 0.0004 SAE 4640 Specimens Normalized 1650 Deg. Average Minutes, Time, For Sawing Rockwell 12.43 49.3 105.5 12.78 49.7 101.4 46.0 94.8 44.8 97.3 45.7 99.2 | 56.2 99.7 12.58 56.7 101.2 12.82 57.8 98.8 51.7 96.8 Specimens Oil Quenched from 1550 Deg. Tempered 900 Deg. Tempered 1200 Deg. | | | Average Time, Average Average Time, Average Seconds, Rockwell Seconds, Rockwell Steel Sawing For Sawing 9440 55.3 37.5 85.0 24.7 54.3 35.0 83.0 20.0 54.5 35.2 84.5 20.8 54.0 36.0 82.0 21.2 55.0 35.0 84.3 21.7 SAE 4640 57.7 38.3 74.7 22.2 59.0 38.5 76.2 22.2 56.3 38.2 76.5 21.0 60.0 33.0 83.7 17.7 THE IRON AGE, July 13, | 7 7 7 | | | | | | | Yield point, per ° ° ° LEFT Variation properties with tempering tempera- ture 9440 series, quenched oil from 1550 deg. Rockwell hardness 240,000 220,000 600 150 900 Tempering time with the fresh saw-blade was not good agreement with later values. one series the results for the last cuts were disregarded, because those values were out line with the others, the saw evidently having be- come dull. Otherwise the results for each steel were good agreement be- tween the various cuts. Average values, corrected for slight variations specimen diameter, are reported Table II, lower figure representing better The Rockwell hardness each steel the same condition heat treatment also included Table II. The lathe-cutting tests reported the sixth column Table prob- ably not show any significant dif- ferences, although the result for steel No. litle better than for the other 9440 steels, and No. was little better than the other SAE 4640 steels. The sawing tests also show only slight differences, the significance which doubtful. general the harder specimens took longer cut, and the softer specimens were cut more quickly, might course expected, though there are some ex- ceptions. One very noticeable excep- tion that all the quenched steels tempered 1200 deg. F., though naturally softer than when tempered 900 deg. F., were less easily ma- chinable. The No. steel was gen- eral the most difficult cut the 52—THE IRON AGE, July 13, 1944 boron, discussed THE IRON AGE article* referred above. The saw- ing tests those steels were unfor- tunately not completed time incorporated that article, but are summarized the present Table The steel numbers here are identified the letter indicate the man- ganese series, and avoid confusion with the other series this report. The tests were made the same man- ner those reported Table II. remarkable difference machin- ability between steels 10M and 2M, and the others evident from the results reported Table III. This difference was checked four times the case steel 10M, and does not seem accounted for its hard- ness. Evidently the higher manganese per cent 1050 = ec RIGHT ties with tempering 10, 9440 series, but was also the hardest. The No. steel, with boron replacing nickel and molybdenum, was the easiest cut with saw, and was not the softest. Among the SAE 4640 steels, No. with boron replac- ing molybdenum was the softest, and the most readily saw-cut the nor- malized condition, but the least readily the quenched and tempered con- dition. All these differences machin- ability were slight, however, and not anywhere near the same magnitude those found saw-cutting the manganese steels with and without 600 150 900 1050 1200 Tempering temperature, and combination steels 10M and gives much greater resistance cutting with saw, than when practically equal hardness obtained with boron treatment and lower man- ganese, with lower carbon steel 8M. the lower carbon steels, sample 9M, boron treated, shows slight superiority over the comparable non-boron but higher manganese ple 8M, since its cutting time sec. less though its average Rock- well hardness points higher. Thus from these saw-cutting tests appears that the boron treated steel have definite advantage machin- 220,000 ur o” Reduction area, per cent Elongation per cent Rock- igher. steel achin- ability over untreated higher man- ganese steels about the same strength and hardness. Drilling tests the same steels, however, did not show any difference that could not explained slight variations hardness. The improved cutting properties sawing, found the boron treated steels the manganese series with about the same hardness and harden- ability were not checked when boron was used place chromium, nickel, molybdenum, where any advantage machinability was comparatively negligible. The difference the man- ganese series was evidently due poor machinability the quenched and tempered steels with more than per cent manganese and 0.3 per cent carbon, rather than any spe- cific influence boron machin- ability. But consistently found all the steels that when boron used place other alloys pro- mote hardenability, the machinability least not impaired. Discussion Results Summarizing the results that have been reported appears that satis- factory hardenability secured 9440 steel without either chro- mium, nickel and molybdenum (ex- cept for residuals obtained from scrap) Carbortam treatment used. the SAE 4640 steel, the Car- [=] Oo ‘o Oo Yield point, w ur hardness 150 bortam treatment gives even better hardenability than 1.2 per cent nickel 0.25 per cent molybdenum, but when molybdenum saved this way should remembered that the hardness slower cooling rates lower, and lower tempering tempera- tures are required for equal strength. The tensile tests oil quenched and tempered specimens showed but little difference between the regular NE9440 steel, and the steels with Carbortam treatment substituted for the chromium, for the nickel and molybdenum. These Carbortam treat- steels had slight advantage impact resistance, though not hard- ness oil-quenched and tempered. the SAE 4640 steel there was ap- preciable difference tensile im- pact properties the quenched and tempered specimens when the Carbor- tam treatment was used place about 1.2 per cent nickel. When Car- bortam was used instead about 0.25 per cent molybdenum, however, the strength was lower and the ductility and impact values higher, the same tempering temperatures. These dif- ferences are corrected has been noted, using slightly lower tempering temperature for the Car- bortam treated non-molybdenum steel. machinability significant dif- ferences between the similarly heat treated steels, other than those expected from slight variations Variation properties with tempering tempera- ture, SAE 4640 series, quenched oil from 1550 deg. impact, 1050 Tempering hardness, were brought out the tests. The results this investigation thus indicate that practically equal tensile properties, and least good, some instances even better, notched-bar impact resistance, are obtained the quenched and tempered condition when treatment with Car- bortam substituted for chromium, SAE 4640 steel. The hardenability and machinability the steels are also not impaired this substitution. The omission molybdenum, how- ever, may necessitate the use slightly lower tempering temperatures for equal properties. important that the correct amounts other alloys are omitted when Carbortam used, for will not replace successfully unlimited amounts other hardening agents, too much the other harden- ing agents present with the boron, excessive hardenability will result. This work indicates that enough Car- bortam added give 0.003 0.004 per cent boron these laboratory melts successfully replaces about 0.6 per cent chromium, 1.2 per cent nickel, 0.25 per cent molybdenum. This equivalent amount chromium higher than has previously been sug- gested, but those for nickel and mo- lybdenum are agreement with pre- vious recommendations. The important feature this use Carbortam its economy com- pared with the other alloys, was pointed out the previous IRON AGE article.* Adding 1.2 per cent nickel steel increases the cost $6.24 per ton; 0.25 per cent molybdenum adds per ton; 0.6 per cent chromium adds $2.40 the steel cost per ton; but even Carbortam per ton costs less than and probably large scale commercial practice less Carbortam would prove suffi- cient. The economy gained from the use Carbortam this way should considerable commercial impor- tance especially since loss the useful properties the steel need incurred taking advantage it. Acknowledgments The author pleased acknowl- edge the capable assistance many friends the staff the Titanium Alloy Mfg. Co., who contributed ma- terially the completion this in- vestigation. Special thanks are due responsible for making most the specimens and tests, and the com- pany for supplying the necessary equipment and for permission pub- lish results. THE IRON AGE, July 13, 1944—53 saw- nfor- are tified man- usion port. man- chin- 2M, the This not hard- 220000 impact tance when ained man- steels, 600 New Type Lead-Zinc Drop Hammer Dies PPROXIMATELY year ago, the foundry section Lockheed, Plant A-2, was faced with steadily increasing demands for drop hammer forming tooling one hand and rapidly decreasing manpower supply the other. order cope with the situation, was necessary that some new method originated that would very drastically cut down the necessary manhours per die. ABOVE: Conventional method casting lead punches into Kirksite dies for drop hammer work utilizes dyke boards lined with asbestos and clamped place shown. The result was radical departure from the accepted method Kirksite die construction and the pouring lead punches these dies. The new method has resulted tremendous BELOW: New type Kirksite die ready for pour- saving manhours, and has made ing Note the high retaining walls. construction which necessitated clamp- ing asbestos lined boards around the die and sealing all joints with plaster clay before punch could ABOVE: Old type die complete with punch, showing large mass non-working metal. BELOW: First stage pouring the lead punch. The three holding studs have been located spider, not shown. The metal poured possible the meeting greatly ac- celerated schedules with very mini- The illustrations clearly show the difference between the old type die poured, and the new type die constructed that the die itself with the top the die. ABOVE: Second stage pouring the pnnch. bars, in. section, are placed around the edge the die and in. more lead poured give clarance between die and hammer. this view some the iron bars have been removed. Note that not necessary seal the joints the iron chills the lead contact. RIGHT: New type die with punch removed. This illustration clearly shows absence large, unnecessary masses metal both punch and die. > XISTING specifications require the rejection magnesium al- loy castings which possess the X-ray negative evidence discon- tinuities localized stress raising type, such cracks, cold shuts, mis- runs and extensive shrinkage voids. the other hand, discontinuities general type, not stress raising nature, although undesirable, are not cause for rejection solely the basis X-ray inspection, but rather, their acceptance rejection must based the results the static test. Such defects are micro-shrinkage, gas po- rosity, blow holes and segregations. Before attempting illustrate exact procedure, the following descrip- tive terminology offered tinent the subject being discussed.* radiographic terminology ap- proved Committee E-7, ASTM, Com- mittee Radiography, American Foun- drymen’s Association and the Canadian Research Council. Stress cracks are fissures that usu- ally are continuous throughout their length. Generally, they exist singly and terminate the surface. Micro-shrinkage, centerline weak- interdendritic piping shown very small cavities occurring be- tween the individual grains, and usually found the thermal center- line the section. The radiographic appearance will vary from general group inter-connected cavities. The supplementing studies X-ray inspection seems indicated certain classes magnesium alloy castings, means for more accurate interpretation what actually exists given speci- men and the sense conserving critical material, time and labor. Although this study appears im- Pose some limitation the absolute Validity some the information from the radiograph, does hot purport discredit the X-ray in- Accurate Inspection Alloy Castings Before any final conclusion can drawn from the radio- graphic examination castings, other pertinent factors must considered. Herein discussed the correlation X-ray testing, metallographic inspection and subsequent operations that will elim- inate peripheral defects. ROBERT TAYLOR Manager, Light Metal Alloy Foundry, State College Washington spector. all justice should remembered that anything but simple matter view radiograph and upon the information presented therein, state with absolute certainty that certain discontinuity represents crack, micro-shrinkage, any the other defects common magnesium alloys when each itself is, rule, minute nature illustrated the X-ray negative. great deal depends the quality the negative af- fected the technique chosen, the fineness grain structure the film being used and the general experience the inspector. would seem essen- tial, however, that X-ray inspectors passing the serviceability mag- nesium alloy castings, first possess some knowledge the peculiarities associated with the metal itself. Cer- tain indications point toward the fact that even the highest quality radio- graph itself rather inadequate for absolute accuracy the interpre- tation defects common magne- sium alloys. Magnesium casting alloys possess- ing the best structural properties fre- quently develop type defect known micro-shrinkage. This is, effect, intergranular voids created shrinkage the last few per cent the liquid alloy freezes. The extent which the voids tend oc- cur depends both the solidification shrinkage and the temperature and range solidification. The numerous magnesium alloys although having lower than average value for solidifi- cation shrinkage have, group, very wide range temperatures over which solidification takes place, and the combination these two properties which makes them sus- ceptible micro-shrinkage.* *“4 Progress Report Magnesium Cast- ing Industry” Washington State Plan- ning Council Project 43, published pri- Differentiation, radiographically, the type defect that exists given casting may “occasionally” made with reasonable accuracy, solely the basis information furnished the X-ray film. This can done comparing the extent the discon- tinuity, its outline, and general char- acteristics with the terminology re- ferred previously. However this instance very close observance, with proper film density and proper illu- mination, required experi- enced operator order arrive any degree accuracy. Therefore, supplement X-ray inspection, metallography should used ascer- tain with absolute accuracy the nature defects common magnesium, when groups castings are in- spected and where single type defect seems persistent one particu- lar design. aid speedy fabrication for all material required the shortest period time consistent with quality standards, and establish uniform THE IRON AGE, July 13, 1944—55 4 4 and y \ standard for accurate subsurface in- spection magnesium alloy castings, which would both fair the con- sumer and foundryman alike, the fol- lowing study was carried out sev- eral magnesium alloy sand castings which were all rejected X-ray in- spection the basis possessing stress cracks. The castings represent- group returned the fabricator rejected the above basis. ABOVE 2—Photograph casting shown Fig. show- ing failure along shaft after mechani- cal test. Bending shaft may noticed where failure took place while the high- stressed area con- taining the defect showed signs failure. LEFT casting show- ing defect. Upon return the rejections they were re-radiographed the foundry and upon evidence furnished the radiographs were interpreted pos- sessing certain amount micro- shrinkage, but showing evidence any stress raising defects, such stress cracks. That the castings were nonstructural design would indi- cate the information contained the specifications that permissible 3—This graph depicts the manner which the casting was loaded. Stress gages were placed the three most critical points where stress raising defect would cause failure. Stresses are plotted against the load pounds. No./ 10,006 20000 30000 40000 56—THE IRON AGE, July 13, 1944 amount micro-shrinkage would allowable; but any rate tioned the specifications they would, the basis containing such shrinkage, subject rejection only the results mechanical testing, The poorest the lot that would not fail the mechanical test would the basis for establishing standard for that particular part. Having determined shrinkage existed, was decided me- chanically test the specimen guide for future control the foun- dry and with the hope arriving definite standard for the casting question. doing was desired establish also the exact identity the defect which would most definitely cause early failure, stress raising nature. casting was selected, which had been radiographed the foundry one the rejected parts, Fig. for mechanical testing examination. this instance the casting was loaded cantilever, simulating the manner which would installed the air- through the hole shown Fig. was applied centrally along the axis the lever. Initial signs failure began show load 225 lb. along the shaft. sign failure appeared the area containing the defect. Absolute failure was indicated 400-lb. load. time during the physical test was there any indication that the casting might fail the area which contained the defect and the obvious conclusion was that, had stress crack existed the suspicious area the casting would have exhibited early failure, perhaps not over 100 Ib. load. The design load was Ib. Illustrated Fig. are both drawing the casting and location various test gages which were placed record stresses the most critical sections the casting. Load was applied compression and stresses plotted against pounds load. Following the mechanical test the casting was sectioned and prepared for metallographic study. Sections were examined through the area which contained the defect ascertain fur- ther the identity the void. The metallographic examination disclosed numerous small cavities existing be- O Onset 250 men- would, micro- only uld not the ard for micro- led me- foun- ving ting sired the finitely raising had sequent this air- nserted own ntrally Initial ata ft. area failure casting ntained clusion existed casting failure, The both ere the and est the ections which fur- The sclosed be- tween the individual grains. None the fissures were continuous may seen the metallographic illus- trations Figs. and From these studies was concluded that micro- shrinkage existed the area sus- picion and evidence stress cracks could found. Summary (1) Radiographic interpretation re- jecting the castings possessing stress cracks was (2) The critical area the casting was relatively sound since stress raising defect would have caused early failure the casting. mini- mum micro-shrinkage such evi- denced results the mechanical test interfere way with service- ability. (3) Accurate typing the defect was accomplished metallographic RIGHT 7—Radiograph hub, illustrating crack, which the basis X-ray inspection would cause rejection. Since machining will remove the defect, the casting sound. BELOW LEFT graphic study per- formed the tested and X-ray inspected casting, revealed small cavities exist- ing between grain boundaries diameters. RIGHT 5—Same Fig. but 200 diameters. examination which was disagree- ment with the original interpretation based X-ray inspection which re- jected the casting. illustrate further the necessity for metallographic examination supplement X-ray inspection, the fol- lowing shows that X-ray inspec- tion performed prior machining wasteful. Fig. shows magnesium alloy casting with hub and rela- tively thin horizontal shell, such would designed for control wheel. The dotted lines show the area that machined out the casting before its installation. graphed the conventional manner, the casting would placed with respect the X-ray film that the hub would the film placed beneath it. The area stress would obviously 6—Drawing control wheel casting with dotted lines show area which will machined off the part. The casting defect occurred outside the remaining area. Dotted line showing machined area &25------ out Sketch casting the region where the thick hub joins the thin shell and somewhat above this location. The as-cast hub cylindrical contour. more than one instance radiographs the hub showed suspicious fine hairline cracks continuous outline, but the depths which could not ascertained X-ray inspection. (See Fig. 7.) The important point for consideration this case is, that illustrated the X-ray film, conformance with exist- ing specifications, such fine hairline cracks are cause for rejection, solely the basis X-ray inspection. many instances, they may not cause for rejection certain machine opera- tions and other methods testing considered. the illustrated case there was some doubt the exact depth the discontinuity and was deemed advisable have metallographic THE IRON AGE, July 1944—57 ‘ studies performed trace the crack its termination and note the depth such termination. view the fact that 0.250 in. was machined out the casting each side the hub, and because the radiographic appearance the defect was inter- esting note that the depth the crack was not sufficient extent impair serviceability the casting. The metallographic studies showed definite disappearance any sign the defect depth 0.80 in. There- fore, after the area was machined out, called for the drawing, per- fectly sound casting would result. view the findings illustrated, and other experiences which occurred prior the current study, felt that metallographic examination should supplemented X-ray in- spection, when certain areas are removed machining. This espe- cially applicable the case mag- nesium alloy castings where fine and similar defects minute nature are present and are illustrated the X-ray film. (1) The continued use X-ray in- spection the sole basis for rejection magnesium alloy castings, when carried out large scale and prior metallographic examination and certain machining operations, appears have very definite limitations conventionally practiced today. Studies carried out determine the value sectional radiography may enhance the value X-ray inspection cer- tain specific cases. sectional ra- diography, synchronized coordinated movement the X-ray tube and film takes place about fixed axis during exposure. This method permits the taking section layer metal predetermined depth, blurring out focus the superimposed surface above defect and also the subsur- face area below the defect. Thus only the area interest shown the film. With proper fulcrum arrange- ment the X-day tube and film sup- port the depth defect can mea- sured centimeters and accurate depth made. (2) Metallography supplemented X-ray inspection offers quantita- tive analysis the typing discon- Defective Aluminum Castings Repaired LARGE percentage the alu- minum turret castings that pre- viously had rejected because porosity and hollow spots are now be- ing repaired the Glenn Martin Co., Baltimore, new process evolved Louis Barrett, tool design process engineer, which the porous material replaced with welding metal. Under the new process the surface 58—THE IRON AGE, July 13, 1944 defects the casting are first re- moved grinding chipping out the porous material. The casting then pre-heated 200 deg. 300 plication local heat. Next the cav- ity welded filled with weld metal using carbon and per cent “Aluminum Weld” welding rod. Finally the welds are carefully cleaned and filed smooth, and the area the porous material has been removed chipping grind- ing, the rounding the cavity heated 200 deg. 300 deg. with torch. second man (in this picture Louis Barrett who devised the stands ready weld soon the required tempera- ture reached. tinuities common magnesium alloys, Where groups magnesium castings are inspected and where specific types discontinuities ap. pear the X-ray negatives, examination should per. formed, sectioning least one the group castings, after which fair standard may set for similar designs containing similar defects. (3) Where considerable machining and where discontinuities are noticed X-ray inspection, studies should performed mine the relationship area machined extent defect. The above conclusions were drawn with the thought conserving much critical material and saving many labor hours are consistent with quality control. Grateful acknowledgment extend- the Department Mining and Metal- lurgy, State College Washington, who carried out the studies. This project was sponsored the Engineering and Experiment Station. Welding covered the weld neutr