渗铌温度与时间对GCr15钢表面渗铌层组织和性能的影响

Effect of Niobiumizing Temperature and Time on Microstructure and Properties of Niobiumizing Layer on GCr15 Steel Surface

采用固体粉末包埋法,在不同温度(910,930,950,970℃)和不同保温时间(1,2,4,5,6 h)下在销轴用GCr15钢表面制备渗铌层,研究了渗铌温度与时间对渗铌层的微观形貌、物相组成、显微硬度、耐磨性能和耐腐蚀性能的影响。结果表明:在不同条件下制备的渗铌层与基体结合紧密,主要由NbC和α-Fe组成;随着渗铌温度的升高或渗铌时间延长,NbC相增多,α-Fe相逐渐消失,渗铌层厚度和显微硬度增大;当渗铌温度为950℃、渗铌时间为2 h时,渗铌层的自腐蚀电位最大,自腐蚀电流密度最小,耐腐蚀性能最好。综合考虑厚度、耐腐蚀性能和耐磨性能,较佳的渗铌工艺为渗铌温度950℃、渗铌时间5 h,在该条件下制备的渗铌层耐腐蚀性能较好,摩擦因数波动小,平均摩擦因数仅为0.22。

Niobiumizing layer was prepared on surface of GCr15 steel for pin shaft by solid powder packing method at different temperatures(910,930,950,970℃)for different holding times(1,2,4,5,6 h).The effect of niobiumizing temperature and time on micromorphology,phase composition,microhardness,wear resistance and corrosion resistance of the niobiumizing layer was investigated.The results show that the niobiumizing layer prepared under different conditions was closely combined with the matrix.The niobiumizing layer was composed of NbC andα-Fe.With increasing niobiumizing temperature or niobiumizing time,the amount of NbC phase increased,theα-Fe phase disappeared gradually,and the thickness and microhardness of the niobiumizing layer increased.When the niobiumizing temperature was 950℃and the niobiumizing time was 2 h,the self-corrosion potential of the niobiumizing layer was the largest and the self-corrosion current density was the smallest,indicating the corrosion resistance was the best.Considering the thickness,corrosion resistance and wear resistance comprehensively,the optimal niobiumizing process was niobiumizing temperature of 950℃and niobiumizing time of 5 h.The niobiumizing layer prepared under this condition had relatively good corrosion resistance and small fluctuation of friction coefficients,and the average friction coefficient was only 0.22.