PHASE TRANSFORMATION AND MECHANICAL PROPERTIES OF MARAGING STAINLESS STEELS
Li Jianchun;Gao Anjuan;Wang Zhanyi Central South Institute of Mining and Metallurgy
Cite this article:
Li Jianchun;Gao Anjuan;Wang Zhanyi Central South Institute of Mining and Metallurgy. PHASE TRANSFORMATION AND MECHANICAL PROPERTIES OF MARAGING STAINLESS STEELS. Acta Metall Sin, 1979, 15(4): 472-481.
Abstract The volume fractions of austenite have been determined on two maragingstainless steels with respect to tempering temperature and time or quenching tem-perature. When the specimens were quenched from 850℃ and tempered under dif-ferent temperatures for 4h, the reverted austenite began to appear at a temperingtemperature of about 550℃, reached its peak value of 24% volume fraction atabout 610℃ and disappeared over 700℃. Under certain definite tempering temper-ature their volume fractions were increased as prolonging the tempering time.And the process seems to be of diffusion controlling. The minimum volume frac-tion of austenite, being near zero, was resulted by being quenched at 1000 or950℃ under same tempering temperature of 580℃ for 4h. The effect of different heat treatment on the microstrain Δα/α of the steels,closely related to phase transformation process of M?A, has also been investigatedby means of X-ray diffraction. The presence of austenite at any 10% would causeloss of strength of both steels about 10 kg/mm~2, however, their toughness mightbe actually improved by these softer austenites formed along the boundaries oflath martensite. In view of combining both strength and toughness of the steelsthe proper heat treatment process to form 5-10% stable reverted austenite wouldperhaps be desirable.
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