模具钢表面激光熔覆镍基合金组织及性能的研究

Research on Microstructure and Properties of Laser Cladding Nickel-based Alloy on Die Steel Surface

模具的失效多在表面产生,通过在H13模具钢表面激光熔覆镍基高温合金涂层修复磨损表面,以延长模具使用寿命。借助XRD、OM、SEM和EDS分析了熔覆层的物相组成、元素分布和激光熔覆工艺参数对模具钢表面镍基涂层宏观形貌和微观组织的影响。结果表明,熔覆层表面光滑,未出现宏观裂纹、气孔和未熔化等现象。随着扫描速度的提高,熔覆层组织生长形态改变,菊花状共晶组织消失,界面组织由胞状晶转变为平面晶,熔覆层底部组织由大量柱状树枝晶和少量胞状晶组成。熔覆层由基体相和强化相组成,γ-(F,Ni)为熔覆层基体相,强化相主要为Ni_(3)Si_(2)、Ni_(6)Si_(2)B1、Cr_(23)C_(6)和Cr B等。熔覆层的硬度较高,平均硬度为565 HV0.2,为基材的2.1倍。

The failure of the die is mostly generated on the surface,and the wear life of the die is prolonged by laser cladding the nickel-base superalloy coating on the surface of the H13 die steel.The effects of phase composition,element distribution and laser cladding parameters on the macroscopic morphology and microstructure of the nickel-based coating on the surface of the die steel were analyzed by XRD,OM,SEM and EDS.The results show that the surface of the cladding layer is smooth,and no macroscopic cracks,pores and unmelted phenomena appear.With the increase of scanning speed,the growth state of microstructure of the cladding layer changes,the chrysanthemum eutectic structure disappears,the interfacial structure changes from cell crystal to planar crystal,and the bottom of the cladding layer consists of a large number of columnar crystals,dendrites and a small number of cell crystals.The cladding layer is composed of matrix phase and strengthening phases,γ-(F,Ni)is the cladding layer matrix phase,and the strengthening phases are mainly Ni_(3)Si_(2),Ni_(6)Si_(2)B1,Cr_(23)C_(6)and Cr B The hardness of the cladding layer is high,and the average hardness is 565 HV0.2,which is 2.1 times than that of the substrate.