冷却速度对超高强马氏体钢的马氏体相变起始温度和硬度的影响

Effect of cooling rate on martensitic transformation initiation temperature and hardness of super high strength martensitic steel

采用热膨胀法测量了马氏体试验钢在20~70℃/s冷却速度下的马氏体相变起始温度(Ms点温度),并研究了其对试验钢硬度的影响。结果表明,冷却速度的提高可增加奥氏体强度、提高奥氏体的热稳定性,进而降低马氏体相变起始温度。同时,更高的冷却速度容易造成晶格畸变,增大位错密度,还会提高过冷度,细化有效晶粒尺寸,使试验钢的硬度提高。

Martensite transformation initiation temperature(Ms temperature) of martensitic steel with cooling rate of 20-70 ℃/s was measured by thermal expansion method, and its effect on hardness of the tested steel was studied. The results show that the increase of cooling rate enhances the strength of austenite, improves the thermal stability of austenite, and then decreases the initiation temperature of martensite transformation. At the same time, a higher cooling rate is more likely to cause lattice distortion, increase the dislocation density, increase the degree of undercooling and refine the effective grain size, which increases the hardness of the tested steel.