快速电弧模式增材制造316L不锈钢组织与性能

Microstructure and properties of 316L stainless steel fabricated by speed arc wire arc additive manufacturing

采用电流恒定的快速电弧模式对316L不锈钢进行电弧增材制造.探索了构件的工艺成形性,并采用金相显微镜与场发射扫描电子显微镜对比研究了成形件不同区域微观组织与力学性能.结果表明,在单层熔覆层内,一次枝晶随着沉积方向从针状树枝晶,薄带状树枝晶向柱状树枝晶转变.同时,二次枝晶尺寸也随着沉积层堆积高度逐渐增大.在试样底部,中部与顶部的二次枝晶臂尺寸分别为11.54μm,12.50μm,15.52μm,其尺寸随着热累积的增加而不断增大.此外,试样沿沉积方向与扫描方向的抗拉强度为517 MPa和527 MPa,均超过了锻材强度.试样断后伸长率为22.5%和15.0%.两种方向的拉伸试样断裂模式均为韧性断裂,但沿扫描方向制造的试样塑韧性优于沉积方向试样.创新点:采用快速电弧模式制造316L不锈钢样品,探讨了单道熔覆层内枝晶形态变化和热累积对二次枝晶臂在试样上部、中部与底部的尺寸变化的影响规律,分析了沉积样品不同方向的拉伸性能.

The 316L stainless steel component was manufactured by speed arc wire arc additive manufacturing(WAAM)under constant current.The formation of the component was explored,and the microstructure and mechanical properties at different regions of the component was compared under the scanning electron microscopes and the metallurgical microscope.The results indicate that the primary dendrites(PD)transform from acicular dendrites,strip dendrites to columnar dendrites along the deposition direction in single layer.The dimensions of secondary dendrites(SD)increases with the deposition height.The secondary dendrite arms sizes(SDAS)are 11.54,12.50μm and 15.52μm at the bottom,middle and top of the sample,which are mainly affected by heat accumulation.In addition,the tensile strength of the sample along the deposition direction and scanning direction is 517 MPa and 527 MPa,exceeding the strength of forging.The percentage elongation after fracture of the sample is 22.5%and 15.0%.And the fracture mode of tensile samples is ductile fracture.However,the plasticity and the ductility of samples adopted along the scanning direction is better than that of the samples in the deposition direction.Highlights:The 316L stainless steel component was fabricated by speed arc mode,the influence of dendrite morphology and heat accumulation in the single layer on the size changes of the secondary dendrite arms in the upper,middle and bottom of the sample was discussed,and the tensile properties of the deposited samples in different directions were analyzed.