Expansion Martensite Martensite Quench cracks Hot Quenched Quenched Quenched Figure 13-12 Formation of quench cracks caused by residual stresses produced during quenching.The figure illustrates the development of stresses as the austenite transforms to martensite during cooling. 40 30 M转变是不彻底的，总要残留少量A 20 10 0.5 女举 0.7 0.91.11.31.51.7 M形成时体积膨胀，产生很大内应力 w(C)/%2.4 钢的热处理(heat treatment of steels) 2.4.2 钢在冷却时的转变 2、过冷A的连续冷却转变  M(Martensite)转变的特点 过冷A转变为M是一种非扩散型转变 M的形成是一个连续冷却的转变过程 M转变是不彻底的，总要残留少量A M形成时体积膨胀，产生很大内应力 （1）共析钢CCT曲线 M为C过饱和的F