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Effect of molybdenum on tempered martensite embrittlement of medium carbon Si‐Mn steels
Author(s) -
Fu Ming,
Qiu Yaojian
Publication year - 1989
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.198900966
Subject(s) - tempering , cementite , molybdenum , materials science , metallurgy , embrittlement , martensite , austenite , carbide , vanadium , microstructure
This paper reports a study of the effects of molybdenum on tempered martensite embrittlement (TME) of medium carbon Si‐Mn steels. The study employed standard U‐notch impact tests, scanning electron fractography, transmission electron microscopy, Auger electron spectroscopy, and dilatometric measurements. It is shown that the addition of molybdenum to Si‐Mn steels does not eliminate TME, but molybdenum acts to decrease the ductile‐brittle transition temperature (DBTT), thus making the impact test temperature for revealing TME lowered. Furthermore, the deferring role of molybdenum on TME is observed. In the molybdenum doped steels the TME embrittlement trough is displaced to a higher tempering temperature. The embrittlement is found to be concurrent with the replacement of ∊‐carbide by cementite during tempering. In the molybdenum doped steels the displacement of TME to a higher tempering temperature is seen to be associated with the role of molybdenum retarding cementite precipitation.