Effect of Molybdenum Content on the Sulfide Stress Cracking Resistance of AISI 4130-Type Steel with 0.035% Cb
1979; Volume: 35; Issue: 6 Linguagem: Inglês
10.5006/0010-9312-35.6.240
ISSN1938-159X
AutoresP. J. GROBNER, D. L SPONSELLER, D. E. DIESBURG,
Tópico(s)Metal Alloys Wear and Properties
ResumoLaboratory heats of ten wrought steels containing 0 to 2.5% Mo and 0.035% Cb and commercial AISI 4130 steel were tested for mechanical properties and sulfide stress cracking (SSC) resistance in the quenched-and-tempered condition. The steels, representing molybdenum variations of columbium modified AISI 4130-type steel, were each tested at several different strength levels. Yield strength increases with increasing molybdenum content. The SSC tests were performed on two types of specimens: (1) simple three-point bending, bent-beam specimens, and (2) environmental fracture toughness specimens of the double cantilever beam type. For steels with a yield strength of 760 MPa (110 ksi), maximum SSC resistance is obtained at a molybdenum concentration of 0.75 or 0.90%, depending on the type of test. These optimum values are rather close to the 0.85% Mo concentration that is necessary to form M2C carbides in the present quenched-and-tempered steels. In both types of tests, the SSC resistance of the 0.75% Mo steel in the cast condition is nearly equal to that in the wrought condition, at a yield strength of 760 MPa (110 ksi). The addition of about 0.08% V provides little, if any, practical benefit in SSC resistant steels of the present type for a yield strength of 760 MPa (110 ksi). The results of SSC tests obtained on bent-beam specimens correlate reasonably well with those obtained on fracture toughness specimens.
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