CMT增材高氮不锈钢的组织与力学性能研究

Study on Microstructure and Properties of High Nitrogen Austenitic Stainless Steel by CMT Additive Manufacturing

采用CMT(cold metal transfer)工艺,选用高氮钢丝材进行电弧增材试验,层层堆积成块体,研究了增材体的组织形成及其性能。结果表明:高氮钢增材体组织为奥氏体和少量的δ-铁素体;层层堆叠的方式决定了树枝晶周期性地向上生长,每个周期的宽度是2.6 mm。一个周期内的增材体树枝晶组织分为三个区域:重熔区域-Ⅰ区域,宽度为0.1 mm;枝晶生长区域-Ⅱ区域,宽度为2.1 mm;热影响区域-Ⅲ区域,宽度为0.4 mm;CMT增材高氮钢的树枝晶组织细小,树枝晶主要是竖直向上生长,局部树枝晶主轴与竖直方向成45°夹角。增材体在水平方向的力学性能比竖直方向好:水平方向的抗拉强度达到872 MPa,伸长率为14%,冲击韧性为258 J/cm^2;而竖直方向的抗拉强度为745 MPa,伸长率为12%,冲击韧性为228 J/cm^2。

The arc additive material test was carried out by using CMT process with high nitrogen steel wire.The bulk was stacked layer by layer.The microstructure of the additive material(AM)bulk was analyzed and the performance was tested.The results show that the microstructure of the high nitrogen steel is composed of austenite and a small amount ofδferrite.The layer stacking determines the periodic growth of the dendrite,and the width of each cycle is 2.6 mm.The dendrite microstructure in each period can be divided into three parts.The width of remelting zone-I is 0.1 mm,the width of dendrite growth zone-II is 2.1 mm,and the width of heat-affected zone-III is 0.4 mm.The dendrite structure of high nitrogen steel bulk is very small.It mainly grows vertically upward,and the principal axis of local dendrite is 45°to the vertical direction.The mechanical properties of AM bulk in horizontal direction are better than those in vertical direction,the tensile strength of the horizontal direction is 872 MPa,the elongation is 14%and the impact toughness is 258 J/cm^2.While the tensile strength of the vertical direction is 745 MPa,the elongation is 12%and the impact toughness is 228 J/cm^2.