氮含量对无镍奥氏体不锈钢力学性能的影响

Effect of nitrogen content on mechanical properties of nickel-free austenitic stainless steel

设计并冶炼了氮质量分数为0.02%～1.20%的无镍奥氏体不锈钢,通过力学性能测试和显微组织观察,研究了氮含量对强度、塑性、韧性的影响。结果表明,氮可显著提高屈服强度和抗拉强度。氮质量分数为0.02%～1.20%时,其与屈服强度和抗拉强度的关系基本为线性关系,并获得了其关系式。韧性对氮含量十分敏感,在氮质量分数为0.39%～0.78%时,冲击吸收功较高,均保持在380J;氮含量过高或过低时,韧性都会下降。氮含量对断面收缩率的影响较小,氮质量分数在0.78%以下时均超过了70%;而氮质量分数超过0.78%后,塑性则有所下降。当氮质量分数超过0.60%时,拉伸断口上韧窝尺寸随着氮含量的升高而逐渐减小;GN-12N钢断口上出现了大面积的无韧窝区。

High-nitrogen nickel-free austenitic stainless steel with different nitrogen mass fraction ranging from 0.02% to 1.20% were designed and melted. The effect of N on the strength, ductility and toughness were investigated through mechanical properties test and microstructure examination. The results showed that N can significantly improve the yield and ultimate strength. The dependencies of them on the N mass fraction (0.02%-1.20%) were linear, and the corresponding equations were obtained. The toughness was very sensitive to the N content. When the mass fraction of N was in the range 0.39%-0.78%, the impact absorption energy was higher, which was maintained at 380 J. However, the toughness decreased if the N content was too high or too low. The influence of N content on ductility was weak. The reduction in area was more than 70% when the N mass fraction was less than 0.78%. The toughness decreased when N mass fraction was above 0.78%. When the N mass fraction exceeded 0.60%, the size of dimples on the tensile fracture surface decreased gradually with increasing the N content. Large areas without dimples were observed on the fracture surface of GN-12N specimen.