US3077397A - Low alloy-air hardening die steel - Google Patents

Low alloy-air hardening die steel Download PDF

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Publication number
US3077397A
US3077397A US108869A US10886961A US3077397A US 3077397 A US3077397 A US 3077397A US 108869 A US108869 A US 108869A US 10886961 A US10886961 A US 10886961A US 3077397 A US3077397 A US 3077397A
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hardening
good
alloy
dimensional stability
applicants
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US108869A
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English (en)
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Paul R Borneman
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Allegheny Ludlum Steel Corp
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Allegheny Ludlum Steel Corp
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Priority to US108869A priority Critical patent/US3077397A/en
Priority to GB17326/62A priority patent/GB945039A/en
Priority to BE617412A priority patent/BE617412A/fr
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese

Definitions

  • the low alloy-air hardening die steel to which the present invention is directed is conventionally used for tools and dies having a design that prohibits the use of water hardening steels because of the hazard of distortion or cracking during hardening.
  • the oil hardening steels generally hold their dimensions less closely than the air hardening compositions. rEhe requirements of such steels are a combination or a balance of deep hardening characteristics, a Wide hardening range, good impact resistance and good machinability in addition to dimensional stability during heat treatment.
  • the aforementioned optimum properties are desired and required, particularly for the manufacture of dies used in punching, coining, piercing, blanking, stamping and trimming of metals and are also useful in the manufacture of hubs, bushings .and master tools where high dimensional tolerances are of importance.
  • a die or tool steel has now been discovered which exhibits deep hardening characteristics, a wide hardening "range, good impact resistance, and is easily machined in addition to exhibiting unusually goed dimensional stability.
  • the present invention is directed to .a steel containing more than about .80% but less than .90% carbon, from 1.85% to 2.15% manganese, .25% to .50% silicon, .75% to 1.l% chromium, from 1.20% to 1.40% .molybdenum and from about .45% to .85% vanadium, the balance being essentially all iron.
  • the carbon content preferably falls within the range of from about .83%
  • sulfur is optionally present within the range of rrom about .08% to .10% to impart improved machinability.
  • FIGURE l is a graphical representation of the dimensional distortion which occurs in the steel of the present invention .as compared with similar prior known compositions;
  • FIG. 2 is a graphical representation of the comparative dimensional stability properties of analyses that constitute another embodiment of the present invention.
  • FIGS. 3 and 4 are cross-sectional views of 4" and 6"' cubes, respectively, showing hardness measurements taken from the center to the edge which illustrate the hardenability of the alloy of the present invention.
  • the parts or dies are conventionally machined in the softer annealed condition and are then heated andquenched to effect maximum hardness for their ultimate use which demands such properties.
  • transformation of the structure of the material to a phase known as austenite is .accompanied by a decrease in size.
  • tempering temperatures Vary from room temperature to 1000 F., but generally occur between the temperature range of from about 400 F. to 650 F.
  • manganese, chromium and molybdenum are present as hardening agents Within the usual and known ranges which are relatively critical in providing optimum deep hardening characteristics and impact resistance.
  • the carbon content is also present as an essential hardening agent, since carbon, .as is well known, is a necessary material for the formation of martensite which is the primary hardening phase. ln the composition of the present invention, however, the carbon is present within critical limitations in that the amount of carbon present must exceed .80% (about .83%) in order to impart the necessary hardening and hardenable characteristics, While 4it must be below .90% (about .87%) in order to retain the excellent stability of the steel.
  • Vanadium also must be within the critical range limitations of from about .45% to .85%.
  • the vanadium carbide precipitates at grain boundary junctions, and having a high solution temperature, controls grain growth and contributes to a wide hardening temperature range.
  • Table III shows the dimensional properties of 1A round samples of the same materials employed to obtain the data shown by Table II and FIG. l. This data confirms the data of Table II in that in nearly every instance, applicants alloy shows far greater dimensional stability than the other grades.
  • FIG. 2 and Table lV there is shown dimensional stability of applicants alloy AL-123EZ for diierent quenching temperatures.
  • FIG. 2 and Table lV also show the comparative dimensional stability of a similar grade identified as XT-028EZ (see Table I). These analyses contain sulfur that has been added to improve machinability.
  • %-inch round x 2.000 long samples were hardened at the recommended temperatures for the respective materials and at temperatures 50 F. above and 50 F. below these temperatures for 8 minutes and air quenched. The specimens were measured (lengthwise) to the fourth decimal place before hardening, after hardening and after each temper. The results were as follows:
  • FIGS. 3 and 4 demonstrate the hardening properties of applicants alloy. These figures show the results obtained when 4" and 6 cubes of applicants alloy (AL- 123) were heated to l550 F., air cooled and cnt in half, then tested for Rockwell C hardness from the edge and corner of each to the center of the former cubes. The results, as shown, clearly illustrate the good deep hardening characteristics of the material. These characteristics are known to be prevalent over la hardening range of l500 F. to 1800 F. Such a wide band of acceptable hardening temperatures is greatly advantageous to a fabricator, since he can use a variety of equipment which may be available to him for such heat treatment and, additionally, can heat treat the material for purposes of quenching with other steels of various grades.
  • Table V shows the wide hardening range of the .AL- 123 analysis. Samples which were air quenched at temperatures of from 1500 F. to 1800 F. are shown to pos- Table VI below, shows the Izod impact properties of the hardened and quenched AL123 analysis. These properties are shown to be equivalent or superior to those possessed by the known commercially available materials.
  • Table VII also illustrates the wide hardening range and line grain size of the alloy of the present invention.
  • the material tested had the analysis reported as AL*123(2) in Table I above.
  • Samples 2 long were cut from 1" round annealed bar stock. They were hardened by holding for 5 minutes at the indicated temperatures and air cooling. Samples were fractured and Shepherd fracture grain size ratings obtained. Hardness measurements were yobtained as quenched and after tempering cumulatively at tempera- 7 tlires of 300 F., 400 lF., 500 F., 600 F., 700 F., 800 F., 900 F. and 1000 ⁇ F. Results are tabulated below:
  • An iron base alloy consisting essentially of greater than .80% and less than .90% carbon, 1.85% to 2.15% manganese, .25% to .50% silicon, .75% to 1.10% chromium, 1.20% to 1.40% molybdenum, .45 to .85% vanadium, the balance iron plus incidental impurities, said alloy Ibeing characterized by good deep hardening characteristics, awide hardening range, good impact resistance, good machinability in the annealed condition and good dimensional stability during heat treatment.
  • An ⁇ iron base alloy consisting of greater than .80% and less than .90% carbon, 1.85% to 2.15 manganese, .25% to .50% silicon, .75% to 1.10% chromium, 1.20% to 1.40% molybdenum, .45% to .85 vanadium, the balance iron plus incidental impurities, said alloy being characterized by good deep hardening characteristics, a wide hardening range, good impact resistance, good machin- 3.
  • An iron base alloy consisting essentially of .83% to .87% carbon, 1.85% to 2.15% manganese, .25% to .50% silicon, .75% to 1.10% chromium, 1.20% to 1.40% molybdenum, .45% to .85% Vanadium, the balance iron plus incidental impurities, said alloy Ibeing characterized by good deep hardening characteristics, a Wide hardening range, good impact resistance, good machinability in the annealed condition and good dimensional stability during heat treatment.
  • An iron base alloy consisting of .83% to .87% car- ⁇ bon, 1.85% to 2.15% manganese, .25% to .50% silicon, .75 to 1.10% chromium, 1.20% to 1.40% molybdenum, .45% to .85% vanadium, the balance iron plus incidental impurities, said alloy being characterized by good deep hardening characteristics, a Wide hardening range, good impact resistance, good machinability in the annealed condition and good dimensional stability during heat treatment.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Articles (AREA)
US108869A 1961-05-09 1961-05-09 Low alloy-air hardening die steel Expired - Lifetime US3077397A (en)

Priority Applications (3)

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US108869A US3077397A (en) 1961-05-09 1961-05-09 Low alloy-air hardening die steel
GB17326/62A GB945039A (en) 1961-05-09 1962-05-04 Improvements in or relating to low alloy-air hardening die steel
BE617412A BE617412A (fr) 1961-05-09 1962-05-09 Aciers de matrices

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US108869A US3077397A (en) 1961-05-09 1961-05-09 Low alloy-air hardening die steel

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BE (1) BE617412A (fr)
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3839022A (en) * 1971-01-28 1974-10-01 Dunford Hadfields Ltd Hot work tools and alloys therefor

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1972524A (en) * 1931-09-30 1934-09-04 Electro Metallurg Co Alloy steel spring

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1972524A (en) * 1931-09-30 1934-09-04 Electro Metallurg Co Alloy steel spring

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3839022A (en) * 1971-01-28 1974-10-01 Dunford Hadfields Ltd Hot work tools and alloys therefor

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BE617412A (fr) 1962-11-09
GB945039A (en) 1963-12-18

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