US3726669A - Elimination of lead embrittlement in steel - Google Patents

Elimination of lead embrittlement in steel Download PDF

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Publication number
US3726669A
US3726669A US00120463A US3726669DA US3726669A US 3726669 A US3726669 A US 3726669A US 00120463 A US00120463 A US 00120463A US 3726669D A US3726669D A US 3726669DA US 3726669 A US3726669 A US 3726669A
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Prior art keywords
steel
lead
embrittlement
rare earth
leaded
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US00120463A
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English (en)
Inventor
N Breyer
S Mostovoy
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Lasalle Steel Co
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Lasalle Steel Co
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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
    • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur

Definitions

  • This invention relates to steels, and more particularly to a method for reducing lead embrittlement in alloy steels.
  • FIG. 1 of the drawing is a graph of percent reduction in area versus temperature.
  • the percent reduction in area for nonleaded steels increases at temperatures above 400 R, which means that the ductility increases with increasing test temperature. This behavior is considered normal for metals; the ductility increases with increasing test temperature.
  • the percent reduction in area decreases rapidly at temperatures above 400 F. and does not recover until a temperature of the order of 900 F. is reached. Therefore, the embrittlement is very severe in this temperature range for leaded steel as pointed out above. Failures during processing or use of leaded steel parts subjected to stress in this temperature range have been encountered.
  • the concepts of the present invention reside in the discovery that the addition of one or more rare earth metals to a leaded steel provides a steel having significantly improved mechanical properties at elevated temperatures.
  • the theory underlying the effectiveness of rare earth metal additives in the present invention is not understood at the present time. While, as indicated above,
  • rare earth meta is intended to refer to and include rare earth elements having an atomic number of 58 or higher as Well as compounds thereof which liberate one or more rare earth metals when combined with steel.
  • Representative of such metals include cerium, neodymium, samarium, praseodymium, gadolium, etc. Due to the fact that many of the rare earth metals are not readily available, and consequently, very expensive, it is frequently preferred to make use of mischmetal, a well known and commercially available mixture of the rare earth metals.
  • the amount of rare earth metal added to the steel depends somewhat on the amount of lead in the steel.
  • leaded steels contain up to about 0.35% by weight of lead, and thus use can be made of sufficient quantities of one or more rare earth metals to provide 0.01 to 0.5% by weight, and preferably 0.02 to 0.2% by weight rare earth metal in the steel.
  • the concepts of the present invention are applicable to any of the steels, including both high and low carbon steels and low, high or no alloy steels containing lead as an additive.
  • the concepts of the present invention may also be applied to steels containing no lead or trace amounts of lead as an impurity to insure that any lead, if present, will be neutralized and not cause failure during the use of such steel in elevated temperature applications, and particularly in applications in which the steel is subjected to stresses at temperature within the range of 400 to 900 F.
  • the rare earth component may be added to the steel in any convenient manner, either before or after addition of the lead. For the sake of simplicity, it is generally preferred to add the rare earth component to a heat of the steel when the lead is added. After addition of the rare earth metal or metals, the heat can be processed in a conventional manner to provide a steel ready for machining having significantly improved mechanical properties at high temperatures, and particularly at temperatures of 400 to 900 F.
  • the bars are then tested at elevated temperatures to determine the embrittlement of the steels, and the results of these tests are shown in FIG. 2 of the drawing.
  • the bars from Heat A containing no rare earths exhibit severe embrittlement at temperatures from 400 to 900 F., particularly in the middle of that temperature range.
  • the bars from Heat B containing the rare earths exhibit a significantly improved reduction in area and consequently significantly improved ductility, over the same temperature range.
  • Example 2 The procedure of Example 1 is again repeated using cerium alone with a heat having substantially the same composition of the heats employed in Example 1. Comparable results are obtained.
  • the present invention provides a needed solution to the problems of failures of leaded steels subjected to stresses at high temperatures which have been experienced in increasing frequency in recent years.
  • a method for the manufacture of articles from steel comprising the steps of adding to molten steel containing lead in an amount sufiicient to cause embrittlement of the steel at least one rare earth metal in an amount sufiicient to eliminate lead embrittle'ment of the steel, forming the resulting steel into an article and subjecting the article to stress at a temperature within the range of 400 to 900 C. whereby the article exhibits improved mechanical properties at temperatures within this range.
  • a method for the manufacture of articles from steel comprising the steps of adding to steel containing lead in an amount sufiicient to cause embrittlement of the steel at least one rare earth element to eliminate lead embrittlement of the steel and forming the resulting steel to form an article having improved mechanical properties at elevated temperatures within the range of 400 to 900 C.
  • the rare I. E. LEGRU, Assistant Examiner earth metal is a mixture of rare earth metals.

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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 Steel (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)
US00120463A 1971-03-03 1971-03-03 Elimination of lead embrittlement in steel Expired - Lifetime US3726669A (en)

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US12046371A 1971-03-03 1971-03-03

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US3726669A true US3726669A (en) 1973-04-10

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US00120463A Expired - Lifetime US3726669A (en) 1971-03-03 1971-03-03 Elimination of lead embrittlement in steel

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US (1) US3726669A (enExample)
CA (1) CA956815A (enExample)
DE (1) DE2159648A1 (enExample)
FR (1) FR2127518A5 (enExample)
GB (1) GB1372099A (enExample)
IT (1) IT955072B (enExample)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4371395A (en) * 1981-07-06 1983-02-01 Southwire Company Technique for adding lead to steel
US10400320B2 (en) 2015-05-15 2019-09-03 Nucor Corporation Lead free steel and method of manufacturing

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4371395A (en) * 1981-07-06 1983-02-01 Southwire Company Technique for adding lead to steel
US10400320B2 (en) 2015-05-15 2019-09-03 Nucor Corporation Lead free steel and method of manufacturing
US11697867B2 (en) 2015-05-15 2023-07-11 Nucor Corporation Lead free steel

Also Published As

Publication number Publication date
FR2127518A5 (enExample) 1972-10-13
CA956815A (en) 1974-10-29
GB1372099A (en) 1974-10-30
IT955072B (it) 1973-09-29
DE2159648A1 (de) 1972-09-14

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