堆焊快速成形低碳钢件的组织与微观力学性能

Microstructure and micro mechanical properties of mild-steel parts fabricated by surfacing rapid forming

采用自制的低碳Ti、B微合金化金属芯焊丝进行了金属零件的堆焊快速成形试验,研究了成形件的组织特征和显微硬度,结果表明:沿沉积高度方向上,成形件的连续组织具有分层特征,珠光体的含量逐渐减少,铁素体的含量逐渐增加,表层主要为块状铁素体,这与成形件各区域的热循环条件和基板材料中C元素的扩散有关;成形件底部和中间区域的显微硬度显著高于表层区域的显微硬度。采用纳米压痕法研究了成形件组织中针状铁素体和块状铁素体的微观力学性能,结果表明:针状铁素体的硬度是块状铁素体的1.28倍,两者的弹性模量相当。因此,获得大量的针状铁素体组织是提高成形件力学性能的重要途径。

The experiment for manufacturing mild-steel parts by surfacing rapid forming with self-made low carbon Ti,B microalloyed metal cored wires was carried out.The microstructure and microhardness of the part were studied.The results indicate that along deposition height direction,the microstructure of the parts shows layered characteristics,the amount of pearlite decreases and the amount of ferrite increases,and the surface zone is mostly composed of massive ferrite.The formation of the microstructure related to the different thermal cycle conditions of each zone in the part and diffusion of carbon from base plate.The microhardness of bottom and middle zones is much higher than that of surface zone.The micro mechanical properties of acicular ferrite and massive ferrite were investigated by nanoindentation technology.The results show that the hardness of acicular ferrite is 1.28 times of that of massive ferrite,and Young＇s modulus of the both ferrite is equivalent.Therefore,it is favourable for high proportion of acicular ferrite in the microstructure to enhance mechanical properties of surfacing forming parts.