LITERATURE SURVEY ON THE INFLUENCE OF ALLOYING ELEMENTS ON THE FRACTURE TOUGHNESS OF HIGH ALLOY STEELS.
Interim technical rept. 13 Mar-13 Jul 69,
TRW EQUIPMENT GROUP CLEVELAND OHIO MATERIALS TECHNOLOGY LAB
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A literature survey was conducted on the effects of alloying elements on the toughness of various high alloy steels. Included in this survey were 12 and 18Ni maraging grades, 9Ni-4Co steels, 5-9Ni age hardening steels, 130150 and 180210 ksi yield strength submarine hull steels and various intermediate experimental steel types. Brief consideration was also given to some lower alloy compositions. The results of the survey indicated that nickel provides the most consistent benefits to toughness. With few exceptions carbon, silicon, and manganese are highly undesirable alloy additions. Tramp impurities such as phosphorus and sulfur are detrimental and large improvements in toughness are observed when these elements are reduced to extremely low levels .002. Cobalt performs multiple functions and is most desirable in steels containing 9 or more nickel. The carbide formers, chromium, and molybdenum behave in an interdependent fashion which varies with steel type. The most consistent benefit these elements as well as other carbide dormers have on toughness is in providing secondary hardening at high tempering temperatures. The use of low carbon or alloy martensites causes the most significant improvements in toughness of high alloy steels. Large increases in strength with minimal loss in toughness are possible with microstructural control by thermal or thermomechanical processing. Austenite grain refinement by thermal cycling is a particularly attractive process for obtaining a high strength-toughness balance in many steels. Author
- Properties of Metals and Alloys