55SiMnMo钢的上贝氏体回火转变

PHASE TRANSFORMATION OF UPPER BAINITE IN 55SiMnMo STEEL DURING TEMPERING

本文通过光学显微镜、X射线衍射、透射电子显微镜和示差扫描热分析等方法,研究了55SiMnMo钢正火状态的回火转变。结果表明:在正火状态的上贝氏体中,铁素体片的平面平行于铁素体{110}_α,同时又是铁素体与奥氏体的共格界面,而且(110)_α//(111)_γ.350℃,1h和400℃,0.5h回火后,渗碳体片状生长,Fe_3C片平面平行于(100)。正火状态的富碳奥氏体的强化主要属于均匀固溶强化,而回火状态的奥氏体强化主要属于非均匀固溶强化。

The transformation of upper bainite of normalized 55SiMnMo steel during temper-ing has been studied by optical microscopy, X-ray difffaction, transmission electron microscopyand differential scanning calorimetry. Ferrite plate surface is parallel to ferrite {110} and isthe coherent interface for α and γ, the crystallographic relationship is (111)_γ(011)α. Thesmall plate surface of Fe_3C precipitated during tempering is parallel to (100). The strengthen-ing mechanizm for carbon-rich austenite in normalized condition is primarily uniform solid so-lution hardening, however, in the tempered state, it is strengthened chiefly by non-uniform one.