不同重熔处理对镍基自溶性粉末合金涂层构件疲劳性能的影响

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In order to investigate the effect of post-fused treatment on the fatigue performance of the com- ponents processed with post-fusion, three types of post-fusing treatment were carried out for specimens that were thermally sprayed in advance with Ni-based self-fluxing alloy coating on 35% steed substrate in electric annealing furnace. Then torsion-bending fatigue tests on them were carried out, and their coating microstructures were observed with scanning electron microscope （SEM）. The result showed that a dis- tinct diffusive layer formed in the interface between the coating layer and the substrate of specimens after different post-fusing treatment and high adhesive strength was observed at the interface, making the fa- tigue strength of the specimen higher than that of the substrate. When the sprayed specimens post-fused with longer heat preservation time, the size and quantity of the porosities in the coating would increase and at the same time, the CrB and Cr7C3 would also formed due to the solidification of Cr in the coating, mak- ing the hardness of both the coating and substrate decreased. Therefore the crack would be initiated prior at the interface of the crack, propagate along the soft substrate, and make the fatigue strength of the spec- imen decreased finally.为了研究重熔处理对构件疲劳性能的影响,以35#钢为基体,以镍基自熔性粉末合金为喷涂材料的热喷涂试样在电退火炉中进行3种不同时间的重熔处理后进行弯扭疲劳试验,应用扫描电子显微镜对不同试样的显微组织进行观察.结果表明：经不同重熔处理后涂层材料均在界面形成了明显的扩散层,涂层与基体的黏结强度高,使喷涂试样疲劳强度均高于基体试样;随着保温时间的延长,涂层中孔隙的大小及数量随之增多.同时,涂层中的Cr固化生成CrB和Cr7C3,导致整个涂层基体硬度降低.从而使裂纹优先在孔隙界面萌生,并沿较软基体扩展,最终使整个试样疲劳强度降低.