固溶+时效对节镍型高氮奥氏体不锈钢力学性能的影响

Effects of Solution+Aging on Mechanical Properties of Ni-saving High Nitrogen Austenitic Stainless Steel

对热轧态节镍型高氮奥氏体不锈钢进行固溶及时效处理。采用显微硬度检测、室温拉伸、TEM等手段,系统分析固溶及时效处理对试验钢力学性能的影响。结果表明,随着时效温度的增加,试验钢的抗拉强度和屈服强度全部呈现先增加后降低的趋势,时效温度为750℃时,强度最高。试验钢的伸长率和收缩率随时效温度的上升而增大,当750℃时效5 h时,试验钢表现出最佳的综合性能。结合透射电镜分析,试验钢拉伸变形过程中呈现出3个阶段。在第Ⅰ阶段,真应力迅速变大,此阶段主要以位错强化机制为主;第Ⅱ阶段,基体软化,加工硬化仍然占主导作用。第Ⅲ阶段,加工硬化速率随着真应变的增加(ε=0.24)而出现了小的平台,然后逐渐减小直至断裂。

Solid solution and aging treatment of hot rolled Ni-saving high nitrogen austenitic stainless steel were carried out.The effects of solid solution and aging treatment on the mechanical properties of the test steel were systematically analyzed by means of microhardness testing,room temperature tension and TEM.The results show that,with the increase of the aging temperature,the tensile strength and yield strength of the test steel show first increase and then decrease.When the aging temperature is 750℃,the strength is the highest.The extension and shrinkage of the test steel increase with the increase of aging temperature.When aging at 750℃ for 5 h,the test steel shows the best comprehensive properties.Combined with transmission electron microscope analysis,there are three stages in the tensile deformation process of the test steel.In stage Ⅰ,the true stress increases rapidly,and the dislocation strengthening mechanism is the main mechanism in this stage.In the second stage,matrix softening and processing hardening still play a leading role.In stage Ⅲ,the work hardening rate generates a small platform with the increase of true strain(ε=0.24),and then decreases gradually until fracture.