奥氏体不锈钢的氨气渗氮处理

用氨气为渗剂,采用不同工艺对0Cr18Ni9奥氏体不锈钢进行渗氮处理。借助光学显微镜对渗氮后试样组织进行分析,结果表明,三段式低温低压渗氮工艺处理后的渗氮层厚度约为90μm,炉压由0.03 MPa增加到0.25MPa后的渗氮层厚度约为135μm,再将第二段温度由550℃提高到950℃后的渗氮层厚度约为220μm,三段式高温加压处理后的渗氮层厚度达到三段式低温低压渗氮层的2.4倍;一段式高温加压处理后的试样硬度HV值为1 100,增大压力和提高温度都能显著提高氮势,增加渗氮层厚度,提高不锈钢的抗腐蚀性能。渗氮影响0Cr18Ni9奥氏体不锈钢的力学性能,在拉伸曲线上出现了锯齿状图形,这与氮化物在拉伸过程中不断开裂有关。

Ammonia nitriding treatment of austenitic stainless steel

To take ammonia as penetrating agent,0Cr18Ni9 austenitic stainless steel is nitriding treated by adopting different process.Specimen structure after nitriding is analyzed by using optical microscope.Results show： nitriding layer depth treated by three segment low temperature low pressure nitriding process is about 90μm,nitriding layer depth after changing furnace pressure from 0.03MPa to 0.25MPa is about 135μm,nitriding layer depth after raising the second segment temperature from 550℃ to 950℃ is about 220μm,the nitriding depth treated by three segment high temperature adding pressure reaches 2.4 times of that of three segment low temperature low pressure treatment,specimen hardness HV value treated by one segment high temperature high pressure is 1100,nitrogen potential can be increased greatly,nitriding depth can be increased by increasing pressure and raising temperature,which can raise anti-corrosion of stainless steel.Nitriding affects mechanical properties of 0Cr18Ni9 stainless steel,zigzag pattern picture presents on stretch curve,which related to different breakage of nitride in stretch process.