成形角度对激光粉末床熔融共晶Al-5Mg-2Si合金中柱状-等轴状组织转变的影响
Role of inclination angle on columnar-to-equiaxed transition in the eutectic Al-5Mg-2Si alloy fabricated by laser powder bed fusion
杨飞鹏 1文涛 1张雷 1汪建英 1黄世龙 1冀守勋 2杨海林1
作者信息
- 1. State Key Laboratory of Powder Metallurgy,Central South University,Changsha 410083,China
- 2. Brunel Centre for Advanced Solidification Technology(BCAST),Brunel University London,Uxbridge,Middlesex,UB8 3PH,United Kingdom
- 折叠
摘要
本文研究了成形角度(0°、30°、45°、60°和90°)对激光粉末床熔融(LPBF)Al-5Mg-2Si合金的柱状-等轴状组织转变机制和力学性能的影响.研究结果表明,在0°试样中,拉伸承载面的熔池呈半圆形态,而在90°试样中最终转变为条状熔池.SEM和EBSD分析结果表明,在0°试样中,微观组织由柱状α-Al晶粒和共晶Mg2Si组成.在90°试样中,α-Al晶粒和共晶Mg2Si最终由柱状结构向等轴状结构转变.α-Al晶粒和胞状Mg2Si的尺寸分别由20.4 μm和0.89 μm细化至10.6 μm和0.44 μm.成形角度为90°的试样表现出最佳强度和伸长率组合,极限拉伸强度为483 MPa,屈服强度为393 MPa,断后伸长率为8.1%.打印态试样的各向异性的力学性能与熔池处的超细微观结构、热应力和熔池边界密度相关,柱状到等轴状的组织转变主要是由于成形角度导致的熔池内部热条件的变化.
Abstract
In this study,the effect of inclination angles relative to the building direction in the additively manufactured eutectic Al-5Mg-2Si alloy was investigated through the laser powder bed fusion(LPBF).The microstructures and mechanical properties of the Al-5Mg-2Si alloy manufactured with different inclination angles(0°,30°,45°,60° and 90°)were reported and discussed.It is found that the"semicircular"melt pool(MP)in the load bearing face of 0° sample was eventually transformed into"stripe-like"MP in the 90° sample,accompanied by an increased fraction of melt pool boundaries(MPBs).Moreover,the microstructural analysis revealed that the columnar-to-equiaxed transition(CET)of the α-Al grains and eutectic Mg2Si was completed in the 90° sample,which were significantly refined with the average size of 10.6 μm and 0.44 μm,respectively.It is also found that the 90° sample exhibited good combination of strength and elongation(i.e.yield strength of 393 MPa,ultimate tensile strength of 483 MPa and elongation of 8.1%).The anisotropic mechanical properties were highly associated with the refined microstructures,thermal stress,and density of MPBs.Additionally,the CET driven by inclination angles was attributed to the variation of thermal conditions inside the local MPs.
关键词
增材制造/铝合金/柱状-等轴状转变/各向异性/力学性能Key words
additive manufacturing/aluminium alloys/columnar-to-equiaxed transition/anisotropy/mechanical property引用本文复制引用
基金项目
National Natural Science Foundation of China(52071343)
出版年
2024
NETL
NSTL
万方数据