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在不添加中间层的基础上,通过调控激光熔覆工艺在低碳钢表面获得均匀、无裂纹、Ti含量超过99%的镀Ti层,并采用数值方法模拟激光熔覆过程,分析了镀Ti层内的温度场和应变场.结合实验和模拟结果、相图和EDS分析,发现熔覆过程中镀Ti层和基体间形成可能由TiFe、共晶金属间化合物(TiFe+β-Ti)和少量α-Ti组成的界面层,该界面层具有本征脆性,极易形成裂纹,且此裂纹无法消除;镀Ti层内裂纹产生的根本原因是在脆性温度区内产生的拉伸应变超过了金属的临界塑形.可通过减少线能量而减少裂纹驱动力,从而消除镀Ti层内的裂纹,获得均匀、无裂纹的镀Ti层.
Without adding the intermediate layer, by controlling the laser cladding process on the surface of mild steel to obtain uniform, no cracks, the Ti content of more than 99% of the Ti layer and the numerical simulation of the laser cladding process, the analysis of Ti The temperature field and the strain field in the layer are analyzed.The results of the phase diagram and the EDS analysis show that the formation of Ti layer and the matrix between the Ti layer and the matrix may be caused by the combination of TiFe, eutectic intermetallic compounds (TiFe + β-Ti) and A small amount of α-Ti interface layer, the interface layer has the inherent brittleness, easy to form a crack, and the crack can not be eliminated; Ti-plated layer cracks caused by the fundamental reason is that in the brittle temperature zone tensile strain exceeds The critical shape of the metal can reduce the crack driving force by reducing the line energy, thereby eliminating cracks in the Ti-plated layer and obtaining a uniform, crack-free, Ti-plated layer.