刘立君 王晓陆 沈秀强 宋袁曾

摘 要：耐热钢H13可用于制作飞机耐热400～500℃工作温度的结构零件，而在飞机有些特殊工作环境下要求其零件表面同时具有耐磨性，因此针对耐热钢在特殊服役环境中磨损失效问题，利用小功率Nd：YAG激光器在H13钢表面熔覆SiC陶瓷颗粒，通过金相显微镜、扫描电镜及能谱分析仪研究不同工艺参数条件下熔覆层显的宏观形貌和微观组织结构。结果表明：熔覆试样横截面出现明显的分层现象（熔覆层、熔合区、热影响区、基体），熔覆层组织致密、无方向性，无明显的气孔裂纹;熔合区组织晶粒较为细小，以树枝晶和等轴晶为主;粗大的柱状晶组织沿H13钢基体熔合线向熔合区生长。SiC陶瓷颗粒熔覆层、熔合区到基体SiK含量存在明显的梯度，表明熔覆层与基体形成了良好的冶金结合，分析了耐热钢表面激光熔覆陶瓷的耐磨性。此外，由于SiC陶瓷颗粒硬而脆的特性以及与基体材料之间热膨胀系数的差异，当扫描速度提高至40mm/min、60mm/min时熔覆层出现了贯穿性裂纹。上述研究成果为提高飞机耐热零件表面耐磨性提供一定理论支持。

关键词：飞机耐热零件;激光熔覆陶瓷;耐磨性

DOI：10.15938/j.jhust.2020.01.019

中图分类号： TG456-7

文献标志码： A

文章编号： 1007-2683（2020）01-0127-07

Abstract：Heat resistance steel type of H13 is used for the aircraft structure parts whose working temperature is 400～500℃Moreover， it is required to wear resistance for the parts in some special service environmentsIn order to solve the problem of wear failure in hot work dies during service， a low power laser type of Nd：YAG was used to cladding SiC ceramics on the surface of H13 steelThe macroscopic feature， microstructures and compositions were observed by the metalloscope， scanning electron microscope and energy depressive spectroscopyExperimental results indicated that that the cross sections of the cladding sample were markedly divisional（Clad Zone， Fusion zone， Heat-affected zone， Substrate Zone）The microstructure of cladding layer is non-directional and compact， without obvious crack and porosity and with good performanceThe homogeneous microstructure of bonding layer is dendrite and equiaxed grain with small size， and the massive columnar crystal grew from the bond line of H13 steel substrate to fusion zoneThe wear resistance of laser cladding ceramics on heat resistance steel surface is analyzed-Besides， a through crack appeared after the scanning speed up to 40mm/min、60mm/min on the cladding layer as the hard and brittle characteristic of SiC ceramics and the difference of thermal expansion coefficient between SiC ceramics and substrate; The above research results provide some theoretical support for improving the surface wear resistance of aircraft heat-resistant parts-

Keywords：heat-resistance parts ofaircraft; laser cladding ceramics; wear resistance

0 引 言

H13鋼具有优良的耐磨性、抗热疲劳、热强度，除在压铸模、热冲裁模、热锻模、热挤压模中得到了广泛应用，也在飞机、火箭等耐热400～500℃工作温度的结构零件上应用[1-2]，有些飞机结构零件除承受较大的冲击载荷、工作介质的冲蚀、高温氧化以及剧烈的冷热循环引起的热应力外，还承受机械磨损[3-4]，提高耐热钢表面耐磨性能，在特定应用环境具有迫切的需求[5]。……