基于电弧增材制造的双相不锈钢熔敷层中δ-铁素体表征

Characterization of δ-ferrite in the Deposited Layer of Duplex Stainless Steel based on Wire Arc Additive Manufacturing

综述了涉及电弧增材制造(wire arc additive manufacturing,WAAM)的双相不锈钢熔敷层中δ-铁素体的特征。结果表明,WAAM的双相不锈钢壁体显微组织是在δ-铁素体基体晶界和晶内分布着不同形态的奥氏体。双相不锈钢填充焊丝化学成分(Cr;/Ni;)对WAAM壁体显微组织的影响非常关键;熔敷工艺的影响亦是通过熔池成分(Cr;/Ni;)的变化来改变相比例的;热输入的影响不明显。试样中δ-铁素体含量过低,以及晶粒粗化对壁体力学性能产生不利的影响。通过焊丝和工艺方法控制熔池成分(Cr;/Ni;),限制δ→γ转变,确保δ-铁素体与奥氏体相比例,同时通过合理选用工艺参数对熔池冷却速度进行控制,以便辅助性遏制δ→γ转变。

The characteristics ofδ-ferrite in the deposited layer of duplex stainless steel involving wire arc additive manufacturing (WAAM) were reviewed.The results show that the microstructure of duplex stainless steel wall of WAAM is composed of austenite with different forms distributed at the grain boundary and in the grain ofδ-ferrite matrix.The chemical composition of duplex stainless steel filler wire (Cr;/Ni;) is very important to the microstructure of WAAM wall.The influence of deposition process is also to change the phase ratio through the change of molten pool composition (Cr;/Ni;);the effect of heat input is not obvious.In the sample,Lowδ-ferrite content and grain coarsening have adverse effects on the mechanical properties of the wall.The composition of molten pool (Cr;/Ni;) is controlled by welding wire and process method to limit the transformation fromδtoγand ensure the ratio ofδ-ferrite to austenite,and the cooling rate of molten pool is controlled by reasonable selection of process parameters,so as to auxiliary restrain the transformation fromδtoγ.