激光淬火对奥氏体不锈钢表面渗氮层相组成及性能的影响

研究了激光淬火对奥氏体不锈钢表面渗氮层相组成和性能的影响。采用X射线衍射仪分析淬火后渗氮层的相组成;采用扫描电镜与能谱仪观察渗氮层截面形貌并测量深度方向上的元素分布;利用球磨仪和电化学方法分别研究淬火对渗氮层耐磨性和耐腐蚀性的影响。结果表明:激光淬火导致低温等离子体渗氮处理生成的γ_N相分解为α-Fe与CrN相;当渗氮层氮浓度较低时,CrN在整个渗氮层中析出,耐磨性明显提高;而当氮浓度较高时,CrN仅在晶界位置析出,耐磨性保持不变。渗氮奥氏体不锈钢经激光淬火后,自腐蚀电位降低,腐蚀电流密度增大,耐腐蚀性降低。

Effect of laser quenching on phase composition and properties of nitrided layer on austenitic stainless steel surface

The effect of laser quenching on phase composition and properties of nitrided layer on austenitic stainless steel surface was studied. The phase composition of the nitrided layer after laser quenching was analyzed by X-ray diffraction, the cross-section morphology of the nitrided layer was observed by scanning electron microscopy and the element distribution in the depth direction was measured by energy dispersive spectrometer. The wear and corrosion resistance of the nitrided layer after laser quenching were studied by ball milling and electrochemical methods, respectively. The results show that laser quenching leads to the decomposition of the γ_N phase generated by low-temperature plasma nitriding treatment into α-Fe and CrN phase. When the nitrogen concentration of the nitrided layer is low, CrN precipitates in the whole nitriding layer, and the wear resistance is obviously improved;while when the nitrogen concentration is high, CrN precipitates only at the grain boundary, and the wear resistance remains unchanged. After laser quenching, the self-corrosion potential of the nitrided austenitic stainless steel decreases, the corrosion current density increases and the corrosion resistance decreases.