【作者】 谢红委；

【导师】 张峻巍；

【作者基本信息】 辽宁科技大学 ， 材料加工工程， 2012， 硕士

【摘要】 镍基高温合金具有较高的高温强度、塑性、组织稳定性及良好的抗氧化和抗腐蚀性能,已广泛应用于航空航天和燃气轮机工业。因其价格昂贵且在极端恶劣环境下使用,国内外十分注视高温合金及其零部件的表面改性及再制造修复。本文以高温合金GH₃044和GH4169为研究对象,采用HGL-6000型连续CO₂多功能数控激光加工设备对GH₃044合金进行激光表面熔凝试验,对GH4169合金进行激光熔覆Co基合金涂层试验,并利用金相显微镜、扫描电镜及显微硬度计测试和分析了熔凝层、熔覆层及其结合区的显微组织和硬度的变化,研究了工艺参数对激光熔凝层和熔覆层组织与性能的影响,以及稀土氧化物Y₂O₃对Co基熔覆涂层的影响。得到以下结论:（1）GH3044合金激光表面熔凝层主要由大量细长柱状枝晶组成;经过900℃时效100h,各工艺条件下熔凝层有大量沉淀相析出,而且P/v越大,析出的沉淀相越细小、弥散;所有熔凝组织经1160℃,1h固溶处理后,晶粒均出现粗化现象,沉淀相也减少;（2）随着激光比能的增加,GH4169合金激光熔覆Co基涂层的稀释率增加,组织也变得粗大;（3）在GH4169合金多道熔覆搭接试验中,各道熔覆层之间的搭接区组织较粗大;而且与相同工艺参数下的单道熔覆层相比,多道搭接熔覆层的稀释率明显增加,硬度也随之下降;（4）添加适量Y₂O₃可细化GH4169合金熔覆层组织,提高硬度,但当加入1.2% Y₂O₃时,熔覆层的硬度有所下降。更多还原

【Abstract】 Ni-based super-alloy has been used widely in the field of aerospace and gas turbines industry due to its higher temperature strength, plasticity, structure stability and nicer oxidation resistance and corrosion resistance. Studies on the surface modification and repairing of Ni-base super-alloy and its component parts have been paid much attention both at home and abroad because of its expensive cost and severe work environment. At present work, the experiments of laser surface remelting of GH3044 alloy and laser cladding Co- based alloy coatings of GH4169 alloy were conducted by the continuous wave HGL-6000 CO2 multifunctional numerical control processing device, respectively. Microstructure and micro-hardness in the remelting layer, cladding layer and binding region were measured and analyzed by means of metallographic microscope, scanning electron microscopy and micro-hardness tester. The effect of laser processing parameters on the microstructure and micro-hardness of laser remelting layer and cladding layer, and the effect of rare earth Y₂O₃ on the Co-based alloy cladding coating were studied. And the results are as follows.（1） The laser remelting layer of GH3044 mainly consists of slender column dendrite. The precipitates occurred in the remelting layer after aging at 900℃in 100h, and the larger P/v is, the crystal particles are finer. The precipitates reduced and the grains got coarser after solution treatment at 1160℃in 1h.（2） The dilution rate of Co-based alloy cladding coating of GH4169 alloy increased with increasing laser specific energy （SE）. The grains got coarser also.（3） The coarse microstructure in the overlapping zone was found for the samples with multi-track overlaps. Moreover, the dilution rate increased and the micro-hardness decreased for the overlapping coatings.（4） The micro-hardness of the Co-based alloy cladding coating of GH4169 alloy increased by adding appropriate rare earth Y₂O₃, but decreased when 1.2%. Y₂O₃ was added.更多还原