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基体材料选用的是45#钢,尺寸为100mm×100mm×10mm。熔覆材料是Ni60镍基合金粉末,规格为140目~325目。其化学成分如表 1所示。
Table 1. Chemical composition (mass fraction) of Ni60
material C Cr Si W Fe B Ni Ni60 0.0080 0.155 0.0400 0.0300 0.1500 0.0350 balance -
通过QM-3SP2行星式球磨机混合得到均匀的粉末,其具体成分如表 2所示。实验前预先将粉末放入干燥箱里加热至150℃并保温30min进行除湿。烘干后将熔覆粉末放入DPSF-2型送粉器进行同轴送粉,采用LYS-6000型IPG光纤激光器和ABB机器人如图 1所示,制备涂层。
Table 2. Specific composition of the cladding material
number component(mass fraction) 1 Ni60+0.004CeO2 2 Ni60+0.006CeO2 3 Ni60+0.008CeO2 4 Ni60+0.010CeO2 5 Ni60 本次试验激光功率设定为1600W,扫描速率为4mm/s,送粉转速为10r/min,送粉气流量为12L/min,搭接率为30%,采用氩气进行保护。激光熔覆试验结束后获得加入不同质量分数的稀土氧化物的5个熔覆层。把制备得到的1号~5号试样对熔覆层进行表面处理,通过着色渗透探伤剂对涂层表面裂纹情况进行表征;在涂层上切出12mm×12mm×3mm的试样,表面处理后通过VHX-900超景深3维显微系统观察显微组织;利用MH-5显微硬度计测试样品显微硬度。
CeO2对激光熔覆Ni60合金涂层组织及性能的影响
Effect of CeO2 on microstructure and properties of Ni60 alloy coating by laser cladding
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摘要: 为了研究稀土元素CeO2对激光熔覆涂层性能的影响,以45#钢为基体、Ni60和Ni60+CeO2粉末为熔覆材料,采用激光熔覆多道搭接工艺制备了含不同含量稀土氧化物的熔覆层。通过对熔覆层着色探伤、显微组织观察、显微硬度测定的试验,分析不同含量的稀土氧化物对熔覆层表面裂纹数量、显微组织、硬度的影响规律。结果表明,CeO2的最佳掺杂质量分数为0.004;适量稀土元素CeO2的掺杂,可使熔覆涂层裂纹数量减少,熔覆层的显微组织更加均匀而细小;熔覆涂层表面显微硬度远高于基体,维氏硬度是基体的3.6倍,搭接区域硬度值是基体的3倍左右。这表明稀土元素的添加可以抑制裂纹、细化晶粒,并在一定程度上提高熔覆层硬度。Abstract: In order to study effect of rare earth element CeO2 on laser cladding coatings, cladding layers with different contents of rare earth oxides were prepared by laser cladding overlap processing, using 45# steel as substrate, Ni60 and Ni60+CeO2 powder as cladding material. Through experiments of cladding layer dye test, microstructure observation, and microhardness mensuration, effect of different contents of rare earth oxides on cladding layer surface cracks' number, microstructure, and hardness was analyzed. The results show that the optimal doping mass fraction of CeO2 is 0.004. The crack number of the cladding coating is reduced and the micro structure of the cladding layer is even and tiny with the doping of rare earth element CeO2. The microhardness of the cladding coating surface is much higher than that of the matrix. The Vivtorinox hardness is 3.6 times of that of the matrix. The hardness of the lapping zone is about 3 times of that of the matrix. The addition of rare earth element can restrain the crack, refine the grain and improve the hardness of cladding layer to some extent.
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Key words:
- laser technique /
- crack /
- laser cladding /
- rare earth element /
- microstructure /
- microhardness
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Table 1. Chemical composition (mass fraction) of Ni60
material C Cr Si W Fe B Ni Ni60 0.0080 0.155 0.0400 0.0300 0.1500 0.0350 balance Table 2. Specific composition of the cladding material
number component(mass fraction) 1 Ni60+0.004CeO2 2 Ni60+0.006CeO2 3 Ni60+0.008CeO2 4 Ni60+0.010CeO2 5 Ni60 -