氮对316LN奥氏体不锈钢力学性能和耐蚀性的影响

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

试验用316LN钢（／％：0．015C、0．65Si、0．90Mn、17．3Cr、12．8Ni、2．6Mo、0．018～0．200N）由50kg真空感应炉冶炼，破真空后加入氮化铬铁，铸锭锻成qb20lnln棒材和热轧成4mm板材，并分别经1100℃30min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9MPa，屈服强度提高7MPa；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7mV；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。

The steel 316LN for test （/% ： 0. 015C, 0. 65Si, 0. 90Mn, 17.3Cr, 12. 8Ni, 2. 6No, 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 dP20 mm bar and hot-rolled to 4 mm sheet, then solid-solution-treated respectively at 1 100 for 30 rain and 10 rain, water quenching. Research results show that with increasing every 0. 010% N in stainless steel 316LN, the steel ten- sile strength and yield strength increase respectively by 9 MPa and 7 MPa, but the steel elongation decreases by 0. 55% , while tile nitrogen content in steel on steel reduction of area has no influence, it keeps to about 72. 5% ; the nitrogen strong- ly improves the pitting corrosion resistance of stainless steel 316LN, with increasing every 0. 010% N, the pitting breakdown potential increases by 7 m ; 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 intergran- ular corrosion resistance of steel.