Difficulties in the geometric and performance control of wire laser additive manufacturing have hindered its widespread application.In this study,an in situ process monitoring system that combines a machine vision-bas...Difficulties in the geometric and performance control of wire laser additive manufacturing have hindered its widespread application.In this study,an in situ process monitoring system that combines a machine vision-based interlayer height controller(IHC)and P-controller-based melt pool temperature controller(MTC)was developed to improve the vertical dimensional accuracy and mechanical properties of off-axis fine-wire laser-directed energy deposition(OAFW-LDED)for 316 L thin-walled parts.The IHC effectively mitigates external defect inheritance,while its synergy with the MTC ensures process stability,improving the vertical dimensional accuracy to±0.2 mm.Grain refinement was achieved by controlling the thermal input to optimize the thermal history and heat accumulation.A heterogeneous microstructure with alternating coarse and fine grains was observed and intergranular thermal cracking was suppressed.The yield and tensile strengths increased from 262 to 416 MPa to 313 and 516 MPa,respectively,with improved consistency in the yield strength between the top and bottom sections.However,excessive laser heat input caused interlayer cracks.Conversely,increasing the heat input through substrate preheating did not induce additional cracks and improved the overall hardness consistency of the thin-walled samples.Therefore,this study proposes a new formability control strategy for OAFW-LDEDs of thin-walled parts.展开更多
以φ1.2 mm TC4钛合金焊丝为原材料,通过激光同轴送丝增材制造技术,结合蛇形正交路径,系统研究了增材试件在不同方向和高度下的力学性能、截面形貌、晶粒度和晶粒取向等之间的联系。研究结果表明,优化工艺参数下,试件表面成形良好(银白...以φ1.2 mm TC4钛合金焊丝为原材料,通过激光同轴送丝增材制造技术,结合蛇形正交路径,系统研究了增材试件在不同方向和高度下的力学性能、截面形貌、晶粒度和晶粒取向等之间的联系。研究结果表明,优化工艺参数下,试件表面成形良好(银白色、无飞溅),内部无气孔、裂纹等缺陷(满足NB/T 47014.2—2015 I级要求)。微观组织分析显示,增材试样底部因多次热循环形成细小网篮组织,中上部的双态组织和魏氏组织特征更为明显。晶粒取向差随高度增加而减小(底部X/Y向分别为45.9°/43.1°,顶部降至37.8°/35.9°)。力学性能测试表明,横向与纵向的抗拉强度(差异2.57%)、断后伸长率(差异4.44%)及冲击韧性(52.6 J和55.3 J)均满足CCS《材料焊接与规范2023》中对TC4板材的要求。此外,由于增材过程中热循环的影响,下层沉积组织晶粒尺寸较小,硬度较高。增材试件在横向和纵向的晶粒度、晶粒取向和组织形态相近,力学性能的各向异性较小。本研究为TC4钛合金激光同轴送丝增材制造技术的工程化应用提供了重要的实验依据。展开更多
基金supported by Open Research Fund of the Sichuan Institute of Xiamen University(Grant No.202401ZDB004)。
文摘Difficulties in the geometric and performance control of wire laser additive manufacturing have hindered its widespread application.In this study,an in situ process monitoring system that combines a machine vision-based interlayer height controller(IHC)and P-controller-based melt pool temperature controller(MTC)was developed to improve the vertical dimensional accuracy and mechanical properties of off-axis fine-wire laser-directed energy deposition(OAFW-LDED)for 316 L thin-walled parts.The IHC effectively mitigates external defect inheritance,while its synergy with the MTC ensures process stability,improving the vertical dimensional accuracy to±0.2 mm.Grain refinement was achieved by controlling the thermal input to optimize the thermal history and heat accumulation.A heterogeneous microstructure with alternating coarse and fine grains was observed and intergranular thermal cracking was suppressed.The yield and tensile strengths increased from 262 to 416 MPa to 313 and 516 MPa,respectively,with improved consistency in the yield strength between the top and bottom sections.However,excessive laser heat input caused interlayer cracks.Conversely,increasing the heat input through substrate preheating did not induce additional cracks and improved the overall hardness consistency of the thin-walled samples.Therefore,this study proposes a new formability control strategy for OAFW-LDEDs of thin-walled parts.
