目的：提高激光表面淬火中金属对激光的吸收效率。方法在65 Mn钢基体表面分别预涂纯SiO2骨料涂剂(1#)、SiO2/Al2O3质量比为11：3的涂剂(2#)及市购某涂剂(3#),采用横流CO2激光加工机进行表面激光淬火处理。对淬火前后的水温值、改性层深度及宽度进行测试,对表面改性层组织及耐磨、耐蚀性能进行表征。结果淬火后,硬化区组织为针状马氏体+少量残余奥氏体；过渡区组织为半马氏体+珠光体+铁素体。涂1#和2#涂剂的试样水温变化量最大,△t=22.9℃。涂1#涂剂的改性层硬度最大,可达到1171.5HV,并且其耐蚀性能最佳,自腐蚀电流密度为112.2μA/cm2。涂2#涂剂的改性层层深及宽度均最大,分别为1.139,7.2 mm,并且其耐磨性最佳,磨损率为2.108 mg/mm2。结论 SiO2可作为激光表面淬火增吸收涂剂的骨料,加入适量的Al2 O3可提高涂剂对激光的吸收效果。
Objective To improve the absorption efficiency of laser in the laser surface quenching. Methods Normalized 65Mn steel was treated by cross flow CO2 laser processing machine, the surface of which was brushed with pure SiO2 aggregate(1#), w(SiO2):w(Al2O3)=11:3(2#) and a purchased coating (3#), respectively. The temperature of sample as well as the depth and width of the surface modification layer was measured before and after quenching to characterize the microstructure, wear resistance and corrosion resistance of the surface modification layer. Results The hardened zone was composed of acicular martensite and a small amount of residual austenite, while the transition region was composed of semi-martensite and pearlite and ferrite. 1#, 2# coating samples showed large temperature changes,△t=22. 9℃. The modified layer of 1# coating sample had the largest hardness, reaching 1171. 5 HV, and its corrosion resistance was the best, with the current density of self-corrosion being 112. 2 μA/cm2 . The depth and width of 2# coating sample were both the biggest, reaching up to 1. 139 mm and 7. 2 mm, respectively, and its wear resistance was the best, with a wear rate of 2. 108 mg/mm2 . Conclusions SiO2 could be used as the aggregate of laser quenching absorption-enhancing coating, performance characterization, besides, the effect of laser absorption could be improved by mixing Al2 O3 in SiO2 .
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