电弧增材高氮钢-316L不锈钢成形异材交织结构

发布时间：2018-05-20 14:58

本文选题：交织结构 + 沉积单道　；参考：《南京理工大学》2017年硕士论文

【摘要】：电弧增材制造以电弧为热源,焊丝为增添材料,快速直接成形致密度高、力学性能好的复杂结构件,具有生产周期短、高利用率、高效率等特点。本课题基于双丝PMIG焊接机器人,以高氮钢与316L不锈钢为研究对象,对增材工艺成形特性及宏观几何尺寸的控制进行分析,开展多道重叠堆积试验和增材工艺参数筛选,进行电弧增材成形异材交织结构的工艺研究。首先针对两种材料分别开展沉积单道成形特性工艺研究,确定了两种材料的增材工艺参数窗口,并探索了增材工艺参数对沉积单道宏观几何尺寸的影响规律。对于高氮钢沉积单道的几何尺寸,沉积速度对于宽度的影响大于送丝速度;沉积速度对于高度的影响略大于送丝速度。对于316L不锈钢沉积单道的几何尺寸,送丝速度对于宽度的影响远远大于沉积速度;沉积速度对于高度的影响大于送丝速度。接着进行了多道重叠堆积试验以及增材工艺参数筛选。分析高氮钢多道重叠堆积出现的缺陷,进一步缩小高氮钢增材工艺参数范围,随后对异材沉积单道几何尺寸、截面面积匹配总误差值进行分析,从而得到最适合用于增材成形异材交织结构的工艺参数,异材重叠堆积最佳道间距d1*=4.3mm,同材重叠堆积最佳道间距分别为d2*=4.2mm,d3*=4.4mm。然后对四种增材成形结构进行微观组织和力学性能分析。异材界面中高氮钢以柱状晶形态沿热流方向生长,316L不锈钢以树枝晶生长;重熔区的组织两次受热作用,两次改变生长方向。交织结构异材界面处,316L不锈钢硬度值变大,高氮钢硬度值变小。交织结构保持较高抗拉强度,延伸率大幅增长,塑性变形能力提高。对于交织结构,冲击两种材料的先后顺序造成吸收冲击功的能力不一样;交织结构内部材料分布不同、成分比例相同,侧面吸收冲击功的能力相近;软硬交织复杂部位正面、侧面冲击功相近,抗冲击能力最强。最后建立典型交织结构三维模型,设计分割层的材料成分比例,提出封闭行走路径减少起弧熄弧次数,提高交织结构局部和整体的成形精度,减少需要后处理加工浪费的材料,增材成形典型交织结构件达到具体几何尺寸要求。
[Abstract]:Arc as heat source, welding wire as additional material, rapid direct forming of high density, good mechanical properties of complex structural parts, with short production cycle, high utilization rate, high efficiency and so on. Based on the dual-wire PMIG welding robot, the forming characteristics and macroscopic geometric size control of the material increasing process are analyzed, and the multi-channel stacking test and the screening of the material increasing process parameters are carried out, taking the high-nitrogen steel and 316L stainless steel as the research object. The process of forming interlaced structure of different materials by arc augmentation was studied. Firstly, two kinds of materials were studied on the characteristics of deposition single pass forming, and the window of material increasing process parameters was determined, and the influence of material increasing process parameters on the macroscopical size of deposition single channel was explored. The effect of deposition velocity on width is greater than that on wire feeding speed, and deposition velocity on height is slightly greater than wire feeding speed for the geometric dimension of single channel deposition of high nitrogen steel. For the geometry size of single channel deposited in 316L stainless steel, the influence of wire feeding velocity on width is much greater than deposition velocity, and deposition velocity on height is greater than wire feeding speed. Then the multi-channel stacking test and the screening of material-increasing process parameters were carried out. The defects of multi-channel overlapping stacking of high-nitrogen steel are analyzed, and the range of processing parameters of high-nitrogen steel is further reduced. Then, the geometric size of single channel and the total error of cross-section area matching are analyzed. Thus, the most suitable process parameters for forming interleaving structure of different materials are obtained. The optimum channel spacing of different material stacking is 4.3mm, and the optimum spacing of overlapping stacking is 4.2mm / d ~ (3) mm / d ~ (4) mm, respectively. Then, the microstructure and mechanical properties of four kinds of forming structures were analyzed. In the interface of different materials, the high nitrogen steel grows in columnar crystal form along the direction of heat flux, and the microstructure of the remelting zone is heated twice and the growth direction is changed twice. The hardness value of 316L stainless steel and high nitrogen steel become larger and smaller at interleaved interface. The interwoven structure maintains high tensile strength, and the elongation increases greatly, and the plastic deformation ability is improved. For interwoven structures, the sequence of impact materials causes the difference in the ability to absorb impact work; the internal distribution of materials in the interwoven structure is different, the proportion of components is the same, and the ability to absorb impact work on the side is similar; the front of the soft and hard interwoven complex parts is similar. The side impact work is similar, and the impact resistance is the strongest. Finally, a three-dimensional model of typical interleaved structure is established, and the proportion of material components in the dividing layer is designed. The closed walking path is proposed to reduce the number of arc extinguishing, to improve the forming accuracy of the local and whole interleaving structure, and to reduce the material waste in post-processing. The typical interlaced parts of material forming meet the requirements of specific geometric dimensions.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG142.71;TG661

【参考文献】