激光重熔镍基合金火焰喷焊层组织及性能

利用金相显微镜(OM)、扫描电镜(SEM)和X射线衍射仪(XRD)分析不同激光工艺参数重熔后的Ni基合金火焰喷焊层及其经不同温度回火处理的显微组织和相组成,并进行了显微硬度和耐磨性测定.试验结果表明,重熔喷焊层的组织主要由γ-(Ni,Fe)固溶体和Cr23C6,Cr7C3,Cr2B,Cr2B,Fe3B,Fe2B等组成,与火焰喷焊层相比,显微组织得到进一步细化,硬度和耐磨性都有较大幅度的提高.在相同工艺条件下,激光扫描速度愈快,显微组织愈敛密、细小,硬度和耐磨性愈好,但重熔喷焊层的熔深较浅;不同激光工艺参数的重熔喷焊层,经不同温度回火后,硬度都得到了进一步的提高;扫描速眨为360 mm/min,经600 C×3 h回火后的重熔喷焊层硬度相比为最高.采用合适的激光重熔处理工艺及随后的热处理,或使Ni基合金火焰喷焊层进一步强化,使用性能得到进一步改善.

Microstructure and Performance of Laser Remelting Ni-Based Alloy Sprayed-Welding Layers

Ni-based alloy flame sprayed-welding layers refusioned under different laser processing parameters, microstructure and phase identity in different temperature drawing temper were investigated using optical microscope (OM), scanning electron microscopy (SEM) and X-ray diffractometer (XRD). The hardness test and wear resistance were also performed. The experimental results show that the phases of the remelted flame sprayed-welding layers mainly consist of γ-(Ni,Fe), Cr23C6, Cr7C3, Cr2B, CrB, Cr5B3, Fe3B and Fe2B. Compared with the flame sprayed-welding layers, microstructure of the remelted sprayed-welding layers are further refined, hardness and wear resistance are obviously enhanced. Under the same technological conditions, microstructure would be more compacted and finer, hardness and wear resistance would be higher with the quicker laser scanning speed, but the penetration of the remelted sprayed-welding layers is relatively shallower. The hardness of the remelted sprayed-welding layers after different temperature drawing temper is increased furtherly and the hardness of the remelted sprayed-welding layers after drawing temper of 600 ℃×3 h with the scanning speed of 360 mm/min is the highest. It indicates that adopting appropriate laser refusioning treating technology and subsequently heat treatment, Ni-based alloy flame sprayed-welding layers would be further strengthened and service performance would be further improved.