3DAP Study of Alloy Element Effects on the Tempering of Steel

摘要

It is well known that the addition of alloy elements such as Si, Cr, Mn, Ni and Mo increases the resistance of carbon-containing martensitic steels to softening during tempering treatments. In the case of high silicon steels, the rate-controlling process has previously been identified as being the rejection of this element during the growth and coarsening of cementite. However, the mechanisms operating in the case of other alloy elements remain obscure. In the present work, we are studying the tempering of an engineering steel, AISI/SAE 4340 (Fe- 1.83at%C - 0.69 Mn - 0.83 Cr - 1.67 Ni - 0.51 Si - 0.15 Mo) in the temperature range 250 C - 600 C. We are using 3-D atom probe techniques to map the redistribution of all major alloying elements between ferrite and carbide phases as a function of temperature and time.