激光重熔对热浸渗铝层组织和性能的影响

热浸渗铝层中通常存在大量的孔洞和裂纹,严重影响渗铝钢的耐蚀性.采用JHM-1GY-400型YAG(晶体)激光器对Q235钢的热浸渗铝层进行激光熔凝处理,借助扫描电镜、电子探针、金相显微镜、X射线衍射仪、显微硬度计等仪器对激光处理前后渗铝层的显微组织、相组成及性能进行了分析.通过测定在3.5%NaCl水溶液中的极化曲线,讨论了激光熔凝处理对渗铝层耐蚀性的影响.结果表明,采用适当的激光处理工艺,可消除渗铝层中的裂纹及孔洞,渗层变得更加致密,从而使其在3.5%NaCl水溶液中的耐蚀性高于未激光处理的渗层.并且其显微组织发生了高铝ξ相(FeAl2)向低铝β2相(FeAl)的转变,导致渗层显微硬度和脆性降低,渗层综合性能得到改善.

Effect of laser remelting on the microstructure and properties of hot-dip aluminized layer

Cracks and defects always appear in the hotdip aluminized layer,which would influence the corrosion resistance of the layer seriously.In order to reduce the cracks and defects,the aluminized layer was treated by laser.The microstructure and properties of laser remelted layer were studied by means of SEM,EPMA,X-ray diffraction and micro-hardness measure. And the anodic polarization curves of the aluminized layer before and after the laser treatment were measured in 3.5% NaCl solution.The results show that the laser remelted layer treated by reasonable parameters has a compact microscopic structure,and it is free from cracks and defects.The phase in the layer is changed from Al-rich phase to Al-poor phase.By laser treatment,corrosion resistance of the hot-dip aluminized layer can be improved,and the microhardness and brittleness can be reduced.