不同Ni含量铁基激光熔覆层组织和性能的研究

目的研究不同Ni含量铁基激光熔覆层的组织和性能。方法采用CO_2激光器制备了不同Ni含量的铁基激光熔覆层,通过奥林巴斯光学显微镜、场发射扫描电镜、X射线衍射仪及洛氏硬度计等设备,对激光熔覆层物相、微观组织及力学性能进行表征。结果当Ni含量为10%~11%时,熔覆层物相主要由γ-Fe相组成,含有少量α-Fe相,洛氏硬度为35.1HRC,熔覆层残余应力宏观上表现为拉应力。当Ni含量为6%~7%时,熔覆层物相主要由α-Fe相组成,含有少量γ-Fe相,洛氏硬度为47.9HRC,熔覆层残余应力宏观上接近平衡状态。当Ni含量为2%~3%时,熔覆层主要由α-Fe相组成,洛氏硬度为60.3HRC,熔覆层残余应力宏观上表现为压应力。结论不同Ni含量熔覆层的物相主要由γ-Fe相和α-Fe相组成,随着Ni含量的降低,熔覆层中γ-Fe相对应的衍射峰强度不断减弱,而α-Fe相对应的衍射峰强度逐渐增强,熔覆层晶粒尺寸减小,表面洛氏硬度增加,残余应力逐渐由拉应力转变为压应力,能够有效抑制裂纹的生成,从而获得高硬度不开裂熔覆层。

Microstructure and Properties of Fe-based Laser Cladding with Different Ni Content

The work aims to study microstructure and properties of Fe-based laser cladding with different Ni content. Fe-based laser cladding with different Ni content was prepared with CO2 laser. Phase, microstructure and mechanical properties of the laser cladding layer were characterized with Olympus optical microscope, field emission scanning electron microscope, X-ray diffractometer and Rockwell apparatus. When the Ni content was 10%~11%, phase of cladding layer was mainly com-posed ofα-Fe phase, and also contained a littleγ-Fe phase, Rockwell hardness was 35.1HRC, and residual stress of cladding layer was macroscopically presented as tensile stress. When the Ni content was 6%~7%, the cladding layer was mainly com-posed ofα-Fe phase, and also contained a littleγ-Fe phase, Rockwell hardness was 47.9HRC, and residual stress of cladding layer was macroscopically close to equilibrium state. When the Ni content was between 2% and 3%, the cladding layer was mainly composed ofα-Fe phase, the Rockwell hardness was 60.3HRC, and the residual stress of the cladding layer was ma-croscopically presented as compressive stress. The cladding layer with different content of Ni is mainly composed ofα-Fe phase andγ-Fe phase. With the decrease of Ni content, the diffraction peak intensity corresponding toγ-Fe phase in the cladding layer weakens continuously, the diffraction peak intensity corresponding toα-Fe in the cladding layer increases gradually, grain size decreases, Rockwell hardness increases, residual stress force gradually transforms from tensile stress into compressive stress, effectively inhibiting the generation of cracks, thereby high hardness non-cracking cladding layer can be obtained.