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为评估[Ni]当量相近、[Cr]当量相同、氮含量不同的奥氏体不锈钢的低温性能和组织稳定性,测试了含氮量分别为0.614%和0.529%的奥氏体不锈钢H1和H2的低温拉伸和低温冲击性能,利用扫描电镜和X射线衍射仪分别对两种试验钢的拉伸断口与冲击断口进行了形貌观察和组织检测,利用TEM分析拉伸断口的显微组织。结果表明:两种试验钢的抗拉强度与屈服强度随着试验温度的降低单调增加,伸长率和断面收缩率逐渐减小,氮含量增加提高材料的强度但降低塑韧性;低温冲击试验的结果是氮含量增加降低试验钢的冲击性能,但对韧脆转变温度影响不大,H1与H2试验钢的韧脆转变温度分别为-122℃与-123℃。XRD与TEM的检测结果均表明此两种试验钢均具有良好的组织稳定性,低温拉伸与冲击均未发生马氏体相变与氮化物析出。
To evaluate the low temperature properties and the microstructure stability of austenitic stainless steels with similar [Ni] equivalent, [Cr] equivalent and different nitrogen contents, austenitic stainless steels H1 and H2 with nitrogen contents of 0.614% and 0.529% The tensile and impact fractures of the two test steels were observed by SEM and XRD respectively. The microstructure of the tensile fracture was analyzed by TEM. The results show that the tensile strength and yield strength of the two kinds of test steels increase monotonously with the decrease of the test temperature, the elongation and the reduction of area decrease gradually. The increase of the nitrogen content increases the strength of the material but decreases the ductility. The results showed that the increase of nitrogen content reduced the impact properties of test steel, but had little effect on the ductile-brittle transition temperature. The ductile-brittle transition temperatures of H1 and H2 test steels were -122 ℃ and -123 ℃ respectively. The results of XRD and TEM indicate that both of the two kinds of test steels have good microstructure stability and no martensite transformation and nitride precipitation occur in low temperature tensile and impact tests.