铁基合金激光熔覆层组织分布及开裂敏感性研究

Investigation on Microstructure and Cracking Susceptibility of Laser-Clad Fe-based Alloy Coatings

在45#钢基底上进行了铁基合金粉末激光熔覆实验。利用扫描电镜观察了熔覆层横断面的金相显微组织形态,对组织的不同特征部位进行了EDS能谱分析,使用X射线衍射仪对熔覆层进行物相分析。结合熔覆层的组织成分分布和激光熔覆过程中组织凝固的特点,分析得到熔覆层中存在少量的Si和B与Fe、Cr、Ni、O结合形成的低熔点共晶,低熔点共晶分布在晶界,尤其是夹杂在熔覆层表层部分,成为裂纹源。调节熔覆材料的成分,减少低熔点共晶产生,可以有效抑制熔覆层的裂纹敏感性。

The experiments of laser cladding of Fe-based composite alloy powder of on steel 45 were carried. The structural observation on the cross-section of laser coatings by a scanning electron microscope （SEM） was performed. The alloying component analysis in minute region by energy spectrum analysis （EDS） and the phase analysis by X-ray diffraction （XRD） were also made. Combining the constituent distribution in the different morphology and the phase analysis with the solidifying characteristic during the laser cladding process, the result can be reached that cracks are apt to be formed due to the dendritic segregation of a little amount of lower-melting component.s with Si, B and Fe, Cr, Ni, O among the structure, especially in the upper part of the coatings, Thus the adjustment of the alloy powder component to reduce the amount of lower-melting phases will be effective to decrease the cracking susceptibility.