等时退火对316L不锈钢低温渗氮层组织及性能的影响

Effects of Isochronal Annealing on Microstructure and Properties of Low Temperature Nitriding Layer of 316L Stainless Steel

研究了退火温度对AISI 316L不锈钢低温渗氮层的S相显微组织成分、表面硬度、耐磨性和耐蚀性的影响。分别在450、470、490℃对低温渗氮试样等时退火4 h,对比未退火的低温渗氮试样,对渗层截面的金相组织、XRD衍射图谱、截面硬度梯度以及在10 N压力载荷下,渗层与YG6碳化钨钢球的磨损行为进行分析,并通过扫描电子显微镜和3D磨痕形貌仪对磨损形貌进行观察,采用电化学工作站研究渗层的耐蚀性。结果表明,退火温度对亚稳态的低温渗氮层S相影响显著,渗层析出程度随退火温度升高而加剧,高温退火使S相分解,析出氮化物,造成基体“贫Cr”,耐腐蚀性能下降。相应地,随着退火温度的升高,低温渗氮层逐渐析出CrN和Fe_(x)N_(y),渗层承载力下降,耐磨性降低。

The effects of annealing temperature on the microstructure,surface hardness,wear resistance and corrosion resistance of S phase of AISI 316L stainless steel in the low temperature nitriding layer were studied.The samples after low temperature nitriding were annealed at 450℃,470℃and 490℃for 4 h.Comparing with the unannealed low-temperature nitride samples,the testing infiltrated layer section microstructure,the XRD diffraction pattern,the cross-section hardness gradient and the YG6 tungsten carbide steel ball under 10N pressure load were analyzed.The wear morphology was observed by scanning electron microscopy and 3D,and an electrochemical workstation was used to study the corrosion resistance of seepage.The results show that the annealing temperature has a significant effect on the S phase of the low temperature nitriding layer,the precipitation degree of infiltrated layer increases with the increase of annealing temperature,nitrides are precipitated after decomposition of S phase by high temperature annealing,as a result,the matrix is"poor Cr"and the corrosion resistance decreases.Corresponding,with the increase of annealing temperature,low temperature nitriding layer precipitates CrN and Fe_(x)N_(y)gradually,the bearing capacity of infiltrated layer decreases and the wear resistance reduces.