氮对316LN奥氏体不锈钢力学性能和耐蚀性的影响

试验用316LN钢(/%:0.015C、0.65Si、0.90Mn、17.3Cr、12.8 Ni、2.6Mo、0.018~0.200N)由50 kg真空感应炉冶炼,破真空后加入氮化铬铁,铸锭锻成Φ20 mm棒材和热轧成4 mm板材,并分别经1 100℃30 min和10min水淬固溶处理。研究结果表明,316LN不锈钢每增加0.010%的氮,抗拉强度提高9 MPa,屈服强度提高7 MPa;伸长率降低0.55%,氮含量对断面收缩率没有影响,约保持在72.5%;氮强烈提高316LN不锈钢的耐点腐蚀性能,每增加0.010%的氮,其点蚀击穿电位提高7 mV;添加适宜的氮(0.079%N),可以改善316LN不锈钢的耐晶间腐蚀性能,过高的氮含量(超过0.120%N)对晶间腐蚀性能有害。

Effect of Nitrogen on Mechanical Properties and Corrosion Resistance of Austenite Stainless Steel 316LN

The steel 316LN for test (/% : 0.015C, 0. 65Si, 0. 90Mn, 17.3Cr, 12.8Ni, 2. 6Mo, 0. 018 ~ 0. 200N) is melted by a 50 kg vacuum induction furnace, adding chromium nitride in atmosphere after vacuum refining. The ingot is forged to Φ20 mm bar and hot-rolled to 4 mm sheet, then solid-solution-treated respectively at 1 100 for 30 min and 10 min, water quenching. Research results show that with increasing every 0. 010%N in stainless steel 316LN, the steel tensile strength and yield strength increase respectively by 9 MPa and 7 MPa, but the steel elongation decreases by 0. 55% , while the nitrogen content in steel on steel reduction of area has no influence, it keeps to about 72. 5% ; the nitrogen strongly improves the pitting corrosion resistance of stainless steel 316LN, with increasing every 0. 010% N, the pitting breakdown potential increases by 7 mV ； and appropriate adding nitrogen in steel (0. 079% N) is available to improve intergranular corrosion resistance of stainless steel 316LN, but excessive nitrogen content (more than 0. 120% N) is harmful to intergranular corrosion resistance of steel.