氮强化高锰奥氏体不锈钢的应变硬化行为

Strain Hardening Behavior of the Nitrogen-strengthened High-manganese Austenitic Stainless Steel

研究了２２Ｍｎ－１３Ｃｒ－５Ｎｉ－０．２５Ｎ钢的应变硬化行为。结果表明：变形初期，形变孪晶的形成降低应变硬化指数；随应变增加，先形成的形变孪晶阻碍位错运动和阻碍其它｛１１１｝形变孪晶形成，从而提高应变硬化指数。应变硬化指数ｎ与真应变量ε的关系为ｎ＝ａ·１ｎｅ＋ｂ。晶粒尺寸对ｎ值的影响与应变量有关，当ε＜０．１时，随晶粒尺寸增大，应变硬化指数先降后升；当ε≥０．１时，应变硬化指数随晶粒尺寸的增大而增加。

The strain hardening behavior of the mitrogen-strengthened high-manganese austenitic stainless steel has been in vestigated by tensile tests at room temporature.The results show that in the early stages of deformation,the formation of deformation twins results in the decrcase of strain hardening exponen t. At higher strains,the preexisting deformation twins act as strong obetacles to both the movement of dislocations and the further formation of deformation twins on other {111},planes,it results in the high strain hardening exponent. Variatfon of strain hardening exponent with true strain is expressed as n=a·1nε+b. The effect of the grain size on strain hardening exponent depends on true strain. When the true strain is less than 0.1 ,with the increase of grain size the strain hardening exponent decreases as it is relatively fine a nd incrcases as the grain size is relatively coarse. When the true strain is greater than 0.1,the strain hardening exponent increases with the increase of the grain size.