论文总字数：30071字

摘 要

电弧增材制造（WAAM）技术是一种将金属焊丝作为增材材料、电弧作为热源，通过熔融增材材料并且层层沉积成型金属零件的制造技术。电弧增材制造技术凭借其固有的快速成型、制造成本低廉的优势吸引了越来越多人的兴趣与关注，其在航空航天、船舶制造等重要工业领域中被广泛运用。本课题基于CMT电弧增材制造技术，通过改变送丝速度对4043铝合金的成型质量、显微组织以及力学性能作进行研究。

基于文献资料确定成型工艺参数，通过改变送丝速度，即送丝速度为7.5m/min、7.0m/min和6.5m/min制备单道单层焊缝，并对其成型质量进行分析。观察发现，在宏观上，随着送丝速度增大，焊接热输入逐渐升高，焊道熔宽增大，焊缝高度也随之增大，增材方向两端逐渐出现咬边现象。

在三种送丝速度工艺条件下，制备多层多道块状试样，表面成型质量观察发现，随着送丝速度增大，试样鱼鳞纹排列逐渐散乱模糊，试样两边由于过高的焊接热输入促进了液态金属流动，会出现塌陷现象，且塌陷现象越来越严重。

对多层多道成型试样的金相组织观察发现：不同送丝速度下试样的显微组织主要为柱状晶，并且带有一部分的等轴晶。随着送丝速度增大，试样中柱状晶会越来越多，并且由于沿增材制造垂直方向散热效率好，焊接热输入逐渐增大，形成较高的温度梯度，柱状晶逐渐沿增材制造垂直方向形成柱状树枝晶。

试样力学性能测试后发现：（1）试样显微硬度分布不均匀。随着送丝速度增加，显微硬度逐渐下降，试样平均显微硬度从71.86HV下降至64.76HV；（2）试样的屈服强度与抗拉强度会随着送丝速度增加而下降。送丝速度为6.5m/min时，屈服强度与抗拉强度达到最大，分别为108.7MPa与146MPa；（3）试样的冲击韧性会随着送丝速度的不断增大而增大。

综合上述试验，送丝速度为6.5m/min时试样成型质量相较于其他试样，无明显塌陷现象，外观较好。力学性能方面，试样中显微组织包含柱状晶与等轴晶，其平均显微硬度值、平均屈服强度与平均抗拉强度均超过其余试样，所以送丝速度为6.5m/min时为最佳工艺参数。

关键词：电弧增材制造 铝合金 成型质量 力学性能

Research on forming process of aluminum alloy using wire arc additive manufacture based on cold metal transfer（CMT）

ABSTRACT

The wire arc additive manufacturing technology is a manufacturing technology that uses metal welding wires as additives and arc as a heat source to melt the additives and deposit metal parts layer by layer. Due to the unique advantages of rapid prototyping and low manufacturing costs, the arc additive manufacturing technology has attracted more and more attention and attention from many people and is widely used in aerospace, shipbuilding and other important industrial fields. Based on the CMT arc additive manufacturing technology, the topic changed the wire feed speed to study the forming quality, microstructure and mechanical properties of 4043 aluminum alloy.

The molding process parameters were determined based on the literature data, the single-bead single-layer weld was prepared by changing the wire feeding speed, the wire feeding speed was 7.5m/min, 7.0m/min and 6.5m/min, and the molding quality was analyzed. It was observed that as the wire feeding speed increased, the fish scale arrangement of the sample gradually became scattered and blurred. Due to the excessively high welding heat input on both sides of the sample, the liquid metal flow was promoted. There will be collapse, and the collapse will become more and more serious.

Under three kinds of wire feeding speed, the multi-layer and multi-channel block samples were prepared, and the surface forming quality was observed that with the increase of wire feeding speed, the arrangement of scales of the sample was gradually scattered and blurred. The excessive welding heat input on both sides of the sample promoted the flow of liquid metal, resulting in collapse, which became more and more serious.

The metallographic structure of the multilayer multichannel molding sample was observed that the microstructure of the sample at different wire feeding speeds was mainly columnar crystal with some equiaxed crystal. With the increase of wire feeding speed, there will be more and more columnar crystals in the sample, and due to the good heat dissipation efficiency along the vertical direction of additive manufacturing, the welding heat input will gradually increase, forming a temperature gradient, which will result in the columnar crystals gradually form columnar dendritic crystals along the vertical direction of additive manufacturing.

After testing the mechanical properties of the samples, it was found that :(1) the microhardness distribution of the samples was not uniform. With the increase of wire feeding speed, the microhardness gradually decreased, and the average microhardness of the sample decreased from 71.86HV to 64.76HV. (2) As the wire feed speed increases,the yield strength and tensile strength of the sample will decrease. When the wire feed speed is 6.5m / min, the yield strength and tensile strength can reach the maximum, respectively 108.7MPa and 146MPa. (3) The impact toughness of the sample will increase with the increase of wire feeding speed.

Based on the above tests, when the wire feeding speed was 6.5m/min, the sample molding quality was no obvious collapse and the appearance was better than other samples. In terms of mechanical properties, the microstructure of the sample contains columnar crystals and equiaxed crystals, and its average microhardness value, average yield strength and average tensile strength all exceed the rest of the samples, so the wire feeding speed of 6.5m/min is the best process parameter.

Key words: Arc additive manufacturing; aluminum alloy; forming quality; mechanical properties

目 录

摘 要 I

ABSTRACT III

目 录 V

第一章 绪论 1

1.1 课题研究的背景与意义 1

1.2 增材制造技术国内外研究现状 1

1.2.1 激光束增材制造技术 1

1.2.2 电子束增材制造技术 2

1.2.3 等离子束增材制造技术 3

1.2.4 电弧增材制造技术 4

1.3 工艺参数对CMT电弧增材制造成型工艺的影响 5

1.3.1 焊接模式 5

1.3.2 送丝速度和焊接速度 6

1.4 研究目的以及主要研究内容 7

1.4.1 研究目的 7

1.4.2 主要研究内容 7

第二章 试验设备和试验方法 8

2.1 试验设备 8

2.1.1 电弧增材制造系统 8

2.1.2 3D CAM成型软件 9

2.2 试验方法 11

2.2.1 金相组织试验 11

2.2.2 显微硬度试验 12

2.2.3 拉伸性能试验 12

2.2.4 冲击韧性性能试验 13

第三章 4043铝合金试样的制备及成型工艺分析 15

3.1 前言 15

3.2 试验方法及工艺参数 15

3.2.1 试验材料 15

3.2.2 单道单层焊缝成型制备 16

3.2.3 多道多层块状试样成型制备 16

3.3 4043铝合金单道单层成型焊道形貌研究 18

3.3.1 4043铝合金单道单层焊缝焊道形貌 18

3.3.2 不同送丝速度下单道单层焊缝焊道形貌比较 19

3.4 4043铝合金多道多层块状成型研究 20

3.4.1 送丝速度在7.5m/min下的多道多层块状成型 20

3.4.2 送丝速度在7.0m/min下的多道多层块状成型 21

3.4.3 送丝速度在6.5m/min下的多道多层块状成型 22

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