摘要
目的针对选区激光熔化成形316L不锈钢的晶粒生长行为难以被观测且观测成本高的问题,预测不同激光功率(P)、扫描间距(h)下选区激光熔化成形316L不锈钢的晶粒类型、尺寸大小及生长角度,探究不同P-h组合对晶粒生长行为的影响规律。方法基于元胞自动机模型,采用全因子法设计16种P-h组合,从微观尺度模拟不同成形面316L不锈钢的晶粒生长变化情况,并对模拟结果进行数据统计分析。结果在平行于激光扫描方向的xy平面上,分布着大量晶粒直径小于60μm的等轴晶;而在垂直于激光扫描方向的xz、yz平面上,晶粒直径大于120μm的柱状晶分布得更多。随着扫描间距的增大,xz、yz两平面上的平均晶粒尺寸不断减小,而xy平面上的平均晶粒尺寸呈现先增大后减小的趋势。当P=150 W、h=0.18 mm时,xy平面上的平均晶粒尺寸最小,绝大部分晶粒直径小于20μm,晶粒生长角度均匀分布在0°~90°,没有出现晶粒生长向大角度偏移聚集的现象。结论不同P-h组合能够通过改变熔池凝固时的冷却速率对选区激光熔化成形316L不锈钢的晶粒生长行为产生显著影响,在较低的激光功率下,适当提高扫描间距能够有效细化晶粒,减少晶粒生长向大角度偏移聚集的现象。
Aiming at the problem of difficulty and high cost in observing grain growth behavior of 316L stainless steel formed by selective laser melting,the work aims to predict grain type,size and growth angle of 316L stainless steel formed by selective laser melting under different laser powers(P)and scanning distances(h)and explore the effect of different 16 P-h combinations on the grain growth behavior.Based on cellular automata model,16 P-h combinations were designed by the full factor method.The grain growth changes of 316L stainless steel on different forming surfaces were simulated from the microscopic scale,and the simulation results were statistically analyzed.In the xy plane parallel to the laser scanning direction,a large number of equiaxed crystals with grain diameter less than 60μm were distributed.In the xz and yz planes perpendicular to the laser scanning direction,the columnar crystals with grain diameter larger than 120μm were mostly distributed.With the increase of scanning distance,the average grain size of xz and yz planes decreased continuously,while the average grain size of xy plane increased firstly and then decreased.When P=150 W and h=0.18 mm,the average grain size in the xy plane was the smallest,and most of the grain diameters were less than 20μm.The grain growth angle was evenly distributed between 0°and 90°,and the migration and aggregation of grain growth to large angle did not appear.Different P-h combinations can significantly affect the grain growth behavior of 316L stainless steel formed by selected laser melting by changing the cooling rate of the molten pool.Under low laser power,increasing the scanning distance can effectively refine the grains and reduce the migration and aggregation of grain growth angle to large angle.
作者
袁美霞
弓懿
刘琪
寇莛彧
柳校可
YUAN Mei-xia;GONG Yi;LIU Qi;KOU Ting-yu;LIU Xiao-ke(School of Mechanical-electronic and Vehicle Engineering,Beijing University of Civil Engineering and Architecture,Beijing 100044,China)
出处
《精密成形工程》
北大核心
2023年第7期156-165,共10页
Journal of Netshape Forming Engineering
基金
国家自然科学基金(52105426)
北京建筑大学研究生创新项目(PG2022134)。
