激光表面处理CuCr50合金的显微组织及性能

目的：细化CuCr50合金的Cr相组织，提高组织均匀性。方法采用Nd：YAG脉冲激光器对CuCr50合金进行表面处理，并对激光处理后合金的显微组织（表面组织和截面组织）、导电性能、显微硬度、耐磨性等进行测试与分析。结果工艺优化后得到的实验参数为：激光功率500 W，峰值5.0 kW，扫描速度4 mm/s，激光频率6 Hz，激光脉宽5 ms，离焦量为+4 mm。在优化的工艺条件下，CuCr50合金经激光表面处理后，形成了致密的重熔层，Cr相的晶粒得到明显细化，合金的组织均匀性提高，表面孔洞减少。合金重熔层中的相组成未发生变化，合金的导电性略微降低，但仍保持了CuCr50合金优良的导电性能。重熔层显微硬度（425~540HV）明显提高，最高硬度为540HV，是基体显微硬度（约240HV）的2.25倍。重熔层的摩擦系数（0.3）远低于原始CuCr50合金（0.45），重熔层的损失质量（0.15 mg）远小于原始CuCr50合金的损失质量（0.6 mg），合金的耐磨性有明显的提高。结论 CuCr50合金在优化的工艺参数条件下进行激光表面处理，能够细化Cr相组织和提高整个合金的组织均匀性，提高合金的显微硬度与耐磨性能。

Microstructure and Properties of CuCr50 Processed by Laser Surface Treatment

ABSTRACT:Objective To refine the Cr phase structure of CuCr50 and improve the uniformity of the microstructure.Me-thodsCuCr50 alloys were treated by Nd:YAG pulsed laser, and the microstructure (surface microstructure and cross-section mi-crostructure), phase, electrical conductivity, microhardness and wear resistance of the alloy were investigated and analyzed after the laser treatment.Results Experimental parameters of process optimization were: laser power 500 W, peak 5.0 kW, scanning speed 4 mm/s, laser frequency 6 Hz, laser pulsed width 5 ms, defocus amount +4 mm. Under the optimized process conditions, dense remelting layer was formed, the size of Cr particles was significantly reduced, the structural homogeneity was improved, the hole was reduced after treatment; The phase composition of the remelting layer were not changed, the electrical conductivity was slightly decreased, but the remelting layer still maintained an excellent conductive performance; Microhardness of the re-melting layer(425~540HV) was obviously improved, the maximum reached 540HV, which was 2.25 times of the substrate (about 240HV). The friction coefficient of the remelting layer (0.3) was much lower than the original CuCr50 alloys (0.45), the weight lost of remelting layer (0.15 mg) was much lower than the original CuCr50 alloys (0.6 mg), and the wear resistance of the alloy had an obvious improvement.ConclusionCuCr50 alloy could be refined, the microhardness and wear resistance could be improved by laser surface treatment under the condition of optimized process parameters.