Internal friction evidence for the carbides-formation in the high Co–Ni martensite steel during heat treatment

Abstract

Abstract The internal friction (IF) behaviors, combined with X-ray diffraction (XRD), dilatometry, and transmission electron microscopy (TEM) analysis of the cryogenic treated and tempered M54 steel were systematically investigated. In IF-temperature curves, the peak P1 was proved to be a Snoek-Ke-Koester (SKK) relaxation peak associated with interstitial carbon atoms in martensite matrix according to its activation energy. The peak P2 and P3 were attributed to reverse martensite transformation and martensite transformation, respectively, during the thermal cycle. Based on the analysis results of IF, XRD and TEM, M2C precipitation indeed occurred during tempering, leading to final ultra-high strength and hardness of the aged M54 steel.