选区激光熔化304L不锈钢的组织结构及力学性能分析

Microstructure and mechanical properties of 304L stainless steel processed by selective laser melting

采用选区激光熔化技术成形304L不锈钢,研究了成形后的显微组织和形貌特征,以及不同构建方向对力学性能的影响。结果表明:304L不锈钢组织中无明显气孔和夹杂缺陷;试样的表面粗糙度随倾斜角度的增大而减小。获得准确完整成形几何特征的前提是,薄壁试样厚度的设计值大于0.3 mm,无支撑圆孔试样直径设计值在1~12.5 mm之间,试样外尖角角度设计值大于5°,试样的内尖角垂直摆放时设计值大于15°,水平摆放时设计值大于8°。不同构建方向对试样的抗拉强度和屈服强度影响不明显,当试样的构建方向与基板呈0°时,试样抗拉强度达到最大值684.7 MPa,当构建方向与基板呈30°时,试样的断后伸长率达到最大为47.7%,同时冲击功达到最大值196.3 J,断裂机制均为韧性断裂。

304L stainless steel was prepared by selectiv|e laser melting(SLM)technology.The microstructure,morphology and mechanical properties of as-fabricated parts were characterized.The results show that no obvious pores and inclusion defects are found in the metallographic structure.The surface roughness of the sample decreases with the increase in the inclination angle during the SLM process.To keep the geometrical characteristics of as-fabricated SLM parts,the thickness of thin-walled specimen should be more than 0.3 mm;the diameter of circular hole without support should be controlled in the range of 1 mm to 12.5 mm;the designed outer sharp angles of the specimen should be more than 5°;the inner sharp angles should be more than 15°when placed vertically to the base plate,and more than 8°when placed horizontally.It is found that the orientation of the specimen axis with respect to the working platform does not influence the tensile strength and yield strength.When the build direction of the specimens is 0°with the base plate,the maximum tensile strength of the specimens reaches 684.7 MPa.When the build direction was 30°with the base plate,the maximum post-fracture elongation of the specimens reaches 47.7%.Meanwhile,the impact energy has the maximum value of 196.3J,and the fracture mechanism is ductile fracture.