摘 要

激光-电弧复合焊接工艺与传统的单独使用激光焊接和电弧焊接相比具有明显优势，使其在高强钢焊接领域具有非常好的应用前景。但激光-电弧复合焊接过程是一个涉及传热、传质、冶金及力学等多个学科的复杂过程，而且工艺参数众多，为了获得最佳焊接参数，单纯依靠理论研究很难解决实际生产中的问题。传统方法是通过不断实验来逼近最佳值，耗费大量的人力、物力，也非常盲目，并不是很好的解决方案。若能通过计算机实现对复合焊接过程进行数值模拟同时配合一定的实验基础，将大幅降低研究成本、节省时间，所以对高强钢激光-电弧复合焊接过程进行数值模拟具有重要科研价值。

本文研究的主要内容包括：首先对低合金高强钢Q345钢板进行激光-电弧复合焊接单道焊和双道焊实验，得到了复合焊接单道焊与双道焊工艺参数，制取宏观试样测量了焊缝截面尺寸，将所得数据作为之后进行数值模拟计算所需的热源参数。

然后建立激光-电弧复合焊接仿真有限元模型，对此前研究人员已经提出的各种焊接热源模型进行对比，分析其优缺点和适用领域，决定采用旋转高斯曲面体热源模型对高强钢复合焊接过程进行数值模拟。通过有限元仿真计算得到复合焊接单道焊和双道焊温度场，对焊接过程的温度场变化进行研究，选取焊缝中心以及焊缝中间截面各点分析其温度随时间的变化规律。

最后在复合焊接温度场的基础上建立应力场有限元模型，得到激光-电弧复合焊接的单道焊、双道焊残余应力分布，分别对整体、纵向和横向残余应力的分布规律进行分析对比。

本文得到了可行的复合焊接数值模拟方法，为复合焊接温度场、应力场分析提供了理论依据和指导。

关键词：激光-电弧复合焊接；高强钢；数值模拟；温度场；应力场

Abstract

The laser-arc hybrid welding process has obvious advantages compared with the traditional single use of laser welding and arc welding, which makes it have a very good application prospect in the field of high-strength steel welding.

However, the laser-arc hybrid welding process is a complex process involving many disciplines such as heat transfer, mass transfer, metallurgy and mechanics, and has many process parameters. In order to determine the best welding parameters, it is difficult to solve the problems in actual production by relying solely on theoretical research. The traditional method is to approach the optimal value through continuous experimentation, which consumes a lot of manpower, material resources, and is very blind, and is not a good solution. If the numerical simulation of the composite welding process can be realized by computer and the experimental basis is matched, the research cost and time can be greatly reduced. Therefore, the numerical simulation of the high-strength steel laser-arc hybrid welding process has important scientific research value.

The main contents of this thesis include: Firstly, the laser-arc hybrid welding single-welded and double-pass welding experiments were carried out on the low-alloy high-strength steel Q345 steel plate. The single-pass and double-pass welding process parameters of the composite welding were obtained, and the macroscopic specimen was measured to measure the weld cross-section size. The resulting data is used as the heat source parameter required for subsequent numerical simulation calculations.

Then establish a laser-arc hybrid welding simulation finite element model, the various welding heat source models that the researchers have proposed have been compared, and their advantages, disadvantages and applicable fields are analyzed. Finally, the rotating Gaussian surface heat source model is used to simulate the high-strength steel composite welding process. The temperature field of composite welding single pass and double pass welding was calculated by finite element simulation. The temperature field variation of the welding process was studied. The welding center and the middle section of the weld were selected to analyze the temperature variation with time.

Finally, the finite element model of stress field is established on the basis of the composite welding temperature field. The residual stress distribution of single-pass and double-pass welding in laser-arc hybrid welding is obtained, and the distribution rules of the overall, longitudinal and lateral residual stress are analyzed and compared.

In this paper, a feasible numerical simulation method for composite welding is obtained, which provides theoretical basis and guidance for temperature field and stress field analysis of composite welding.

Key Words：laser-arc hybrid welding; high strength steel; numerical simulation; temperature field; stress field

目录

摘 要 I

Abstract II

第1章 绪论 1

1.1研究背景与选题意义 1

1.2激光-电弧复合焊接概述 2

1.2.1激光-电弧复合焊接原理及其特点 2

1.2.2复合焊接国内外研究现状 4

1.3激光-电弧复合焊接数值模拟发展现状 5

1.3.1焊接数值模拟研究现状 5

1.3.2数值模拟热源模型发展现状 5

1.4有限元方法介绍 7

1.4当前研究存在的问题 8

1.5论文主要研究内容 8

第2章 高强钢激光-电弧复合焊接实验 10

2.1实验内容 10

2.1.1实验材料 10

2.1.2实验设备 10

2.1.3实验方案 11

2.2实验结果 12

第3章 激光-电弧复合焊接温度场仿真 13

3.1复合焊接数值模拟热力学理论 13

3.1.1热传导 13

3.1.2热对流 13

3.1.3热辐射 13

3.1.4焊接温度场的基本方程 14

3.2焊接有限元模型的简化 14

3.3有限元分析模型的建立 16

3.3.1建立几何模型 16

3.3.2材料属性 17

3.3.3确定单元类型 17

3.3.4网格划分 18

3.3.5确定热源模型 18

3.3.6相变潜热的处理 20

3.3.7热源的加载 20

3.4单道焊温度场计算结果与分析 21

3.5双道焊温度场计算结果与分析 25

3.6本章小结 28

第4章 激光-电弧复合焊接应力场模拟 29

4.1焊接应力和应变的分析理论 29

4.1.1屈服准则 29

4.1.2流动准则 30

4.1.3强化准则 30

4.1.4应力应变关系 30

4.1.5平衡方程 31

4.2复合焊接应力场有限元模型建立 32

4.2.1确定塑性模型与材料属性 32

4.2.2设置边界条件 33

4.2.3加载计算 33

4.3单道焊应力场计算结果与分析 34

4.3.1单道焊整体残余应力 34

4.3.2单道焊纵向残余应力分布 34

4.3.3单道焊横向残余应力分布 36

4.4双道焊应力场计算结果与分析 37

4.4.1双道焊整体残余应力 38

4.4.2双道焊纵向残余应力分布 38

4.4.3双道焊横向残余应力分布 39

4.5本章小结 41

第5章 总结与展望 42

5.1全文总结 42

5.2展望 42

参考文献 44

致谢 46

第1章 绪论

1.1研究背景与选题意义

焊接是指通过加热、温或者高压的方式使两种或两种以上同种或异种材料产生原子或分子之间的结合和扩散的一种制造工艺，这是一种古老的材料加工技术，最早甚至可追溯至青铜时代，在20世纪初焊接技术取得革命性进展，随后在工业生产过程中焊接工艺开始普及，实用价值的提升促进了各国研究人员对焊接的研究，各种不同焊接方式被陆续提出，焊接质量也在不断提升，直到今天，焊接更是先进制造领域不可或缺的重要加工工艺。

电弧焊接是在材料连接领域得到广泛应用的一种相当成熟的金属连接技术。由于电弧焊接采用电弧作为焊接热源，利用电弧比较强的桥接能力使得不需要严格要求焊接工件间隙，操作更加简单，而且还具有设备投资成本低、应用范围广等优点。但电弧焊接也有一些明显的缺点，如焊接速度较慢、焊缝深宽比小、焊后变形大以及实际生产效率低等缺陷^[1]。