钛合金多层多道电弧增材制造成形特性研究
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摘要
采用Ti6321A焊丝进行电弧增材制造,研究层与层、道与道之间的金相关系,表征多层多道增材组织特征,分析其对性能的影响规律。结果发现,交错式堆积方式获得的增材制造部件,成形良好,内部无缺陷。终道熔敷层,晶粒较为粗大,最后形成贯穿上下2层焊缝的柱状晶,内部主要为针状马氏体和残余β相;中部存在层间和道间2种位置结构,其中层间交界组织受到3次热循环,柱状晶被破碎,晶粒趋向于等轴晶,而且α相含量增多;而层间填充部分,由于冷却速度较快,高温停留时间较短,形成细小密集的魏氏组织;道间出现了较为明显的晶粒尺寸差异,这与道间温度过高、熔敷层表面出现凹坑、在2次填充时出现不同熔敷层"混层"现象有关。基板与增材界面热输入小,晶粒较为细小,同时由于后热作用晶粒得到一定程度的破碎,趋向于等轴化,而且进一步降低了界面处的应力水平。拉伸试验结果显示,增材制造材料的平均抗拉强度为870 MPa,断后伸长率为13.3%,上下2层增材制造的材料均匀性较好,没有上下层的明显差异,表现出稳定的力学性能。
With Ti6321A wire arc material manufacturing, the relationship between layer and pass were researched.The metallographic characterization of multi-layer and multi-pass microstructure characteristics and the influence on the performance were analyzed. The results showed that crisscross type packing way for increasing material manufacturing parts were formed well, without internal defects. In the last deposition layer, grain was relatively bulky, and columnar crystal through two weld layer formed, with acicular martensite and residual beta phase. There were interlayer and inter-pass two kinds of structure in the middle of deposition. The microstructure in the inter-layer experienced three times of thermal cycle, so the columnar crystal was broken to isometric crystal grains, and α content increased. While in the inter-pass, there were obvious differences in grain size due to the difference in deposit temperature. The heat input between base plate and additive interface was small, so grain was relatively small, at the same time due to the thermal effect, a certain amount of grain were crushed to be equal grain, and the interface stress level was reduced. The average tensile strength of additive material reached 870 MPa with elongation 13.3%.Additive material uniformity was good, and there was no obvious difference on the layers, which exhibited stable mechanical properties.
With Ti6321A wire arc material manufacturing, the relationship between layer and pass were researched.The metallographic characterization of multi-layer and multi-pass microstructure characteristics and the influence on the performance were analyzed. The results showed that crisscross type packing way for increasing material manufacturing parts were formed well, without internal defects. In the last deposition layer, grain was relatively bulky, and columnar crystal through two weld layer formed, with acicular martensite and residual beta phase. There were interlayer and inter-pass two kinds of structure in the middle of deposition. The microstructure in the inter-layer experienced three times of thermal cycle, so the columnar crystal was broken to isometric crystal grains, and α content increased. While in the inter-pass, there were obvious differences in grain size due to the difference in deposit temperature. The heat input between base plate and additive interface was small, so grain was relatively small, at the same time due to the thermal effect, a certain amount of grain were crushed to be equal grain, and the interface stress level was reduced. The average tensile strength of additive material reached 870 MPa with elongation 13.3%.Additive material uniformity was good, and there was no obvious difference on the layers, which exhibited stable mechanical properties.
引文
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[3]巩水利,锁红波,李怀学.金属增材制造技术在航空领域的发展与应用[J].航空制造技术,2013(13):66-71.
[4]Keieher D M,Smugeresky J E,Romero J A,et al.Using the laser engineered netshaping(LENS)process to produce complex components from a CAD solid nodel[C]//Proceedings of SPIE,the International Society for Optical Engineering,Orlando,USA,1997.
[5]陈济轮,杨洁,于海静.国外高能束增材制造技术应用现状与最新发展[J].航天制造技术,2014,8(4):1-4.
[6]Wang H,Kovacevic R.Variable polarity GTAW in rapid prototyping of aluminumparts[C]//Proceedings of the 11thAnnual Solid Freeform Fabrication Symposium,Austin,USA,2000.
[7]徐富家.Inconel 625合金等离子弧快速成形组织、控制及工艺优化[D].黑龙江哈尔滨:哈尔滨工业大学,2014.
[8]Skiba T,Baufeld B and Biest O.Microstructure and mechanical propertiesof stainless steel component manufactured by shaped metal deposition[J].ISIJ International,2009,49(10):1 588-1 591.
[9]高福洋,赵文光,高奇,等.电弧增材制造成形工艺影响因素研究[J].材料开发与应用,2017,3(2):59-63.