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激光功率和扫描策略对TiC增强高碳钢硬质合金层开裂行为影响规律

Influence of laser power and scanning strategy on the cracking behavior of TiC reinforced high carbon steel alloy

  • 摘要: TiC增强高碳钢硬质合金是一种在工业领域得到广泛应用的耐磨材料,但在激光熔覆制备过程中容易产生裂纹. 文中采用仿真分析和熔覆试验确定了激光功率和扫描策略对硬质合金裂纹行为的影响规律. 借助ANSYS软件采用有限元法确定激光熔覆后熔覆层中的温度梯度和残余应力分布,采用扫描电子显微镜(SEM)对显微组织进行分析,结果表明,激光功率和扫描策略不同会导致在熔覆层内产生不同的热梯度分布、残余应力分布以及物相组织演变,这是造成熔覆层具有不同开裂倾向性的主要原因. 高激光功率结合往复扫描策略带来了高热输入和低温度梯度,可有效减少开裂倾向. 随着激光功率的增加,TiC陶瓷相会熔化溶解,合金明显呈现回火组织特征,逐渐形成贝氏体组织和回火马氏体组织,进一步有利于降低裂纹产生的倾向.

     

    Abstract: TiC reinforced high carbon steel hard alloy is a widely used wear-resistant material in the industrial field, but cracks are prone to occur during laser cladding preparation. The influence of laser power and scanning strategy on the crack behavior of hard alloy was investigated through simulation analysis and cladding experiments in the article. Using ANSYS software and finite element method, the temperature gradient and residual stress distribution in the laser cladding layer were investigated. Scanning electron microscopy (SEM) was used to analyze the microstructure. The results showed that different laser power and scanning strategies would lead to different thermal gradient distribution, residual stress distribution, and microstructure evolution in the cladding layer. This is the main reason for the different cracking tendencies of the cladding layer. The combination of high laser power and reciprocating scanning strategy brings high heat input and low temperature gradient, which can effectively reduce the tendency of cracking. With the increase of laser power, TiC ceramic phase will melt and dissolve, and the alloy will exhibit obvious tempering microstructure characteristics, gradually forming bainite and tempering martensite structures, which further helps to reduce the tendency of crack generation

     

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