热处理工艺对预硬型模具钢组织转变的影响

The effect of heat treatment on the microstructures transformation of prehardened plastic mould steels

利用热膨胀仪对实验预硬型塑料模具钢的不同热处理工艺进行模拟,并对其组织及原奥氏体形貌进行观察,同时用扫描电镜及透射电镜对组织内的碳化物进行能谱分析,研究发现,晶粒度对实验钢淬透性影响很小.880℃保温得到的铁素体组织的晶界处存在碳的Cr-Mn-Fe型化合物,少部分碳化物中还发现有Mo元素的存在,碳化物中出现Mo元素后,Cr及Mn元素含量也随之增加.这些碳化物容易诱发铁素体形核并长大,而硼元素难以抑制此类铁素体的生成.920℃保温碳化物溶入基体后,铁素体将不再产生.

Dilatometric tests were performed on the dilatometer under different heat treatments for the prehardened plastic mould steels,the microstructures and the prior austenite were observed.The carbide in the microstructures was analyzed with the SEM and TEM.The effect of grain size on the hardenability of the steel is little.There are lots of carbide of Cr-Mn-Fe,minority of them contains the element of Mo,and with Mo,the content of Cr and Mn raises.This carbide induces the nucleation and growth of ferrite which couldn＇t be inhibited by the element B.The carbide would dissolve at 920 ℃ and the ferrite could not nucleate.