M-A组织对热影响区缺口韧性的影响

通过热模拟试验，对加热到1350℃的四种低合金高强度钢进行了不同冷却速度的连续冷却，并进行了不同温度回火的热循环，研究了M-A（马氏体一奥氏体）组织的析出形态及其分解、M-A组织百分比、奥氏体晶粒尺寸和元素含量对模拟热影响区（HAZ）硬度和冲击韧性的影响。指出块状M-A是影响缺口韧性的主要因素。通过控制连续冷却时间和冷却后给以适当的回火工艺，可以减少或分解块状M-A组织，并可使热影响区的缺口韧性得到改善。

EFFECT BY M-A STRUCTURE ON NOTCH TOUGHNESS OF HEAT-AFFECTED ZONE

With relevant thermal simulation tests, continuous cooling of four high-strength low alloy steels at different cooling rates were conducted. Also conducted with the said steels were thermal circulation of tempering at different temperatures. Analyzed with the said tests were such aspects concerning the steels as separation pattern and resolution of M-A (martensitic-austenitic) structure,percentage of the M-A structure and effects by austenitic grain size and chemical element contents on the hardness and impact toughness of the heat--affected zone (HAZ). It is concluded that since lump M-A is mainly responsible for notch toughness of the steels,it is possible to reduce or resolve the lump M-A structure to improve the HAZ notch toughness by means of proper control of continuous cooling time and post-cooling tempering.