摘要本文针对超高强6211钢中薄板对优质焊缝接头的需求，开展机器人光纤激光焊接技术的试验研究，重点以激光焊接中影响最显著的激光功率、焊接速度、离焦量三个工艺参数为变量设计了对比试验，对6211钢的焊接性和激光焊接工艺进行了较为深入的试验研究和理论分析。通过外观形貌、X射线质量、微观组织、显微硬度、拉伸实验以及电子能谱等检测手段，对6211超高强钢焊缝接头性能和组织特点进行了分析研究，得出了不同焊接工艺参数对力学性能与微观组织的影响规律，形成了最优的焊接工艺规范窗口。87870

从实验成果来看，6211超高强钢碳当量高、硬脆组织等不均匀组织严重，焊接性差，但中薄板试件激光焊接性仍具有一定的焊接性，通过适当的工艺参数协调配合，可以得到无裂纹、未熔合等缺陷的焊接接头，焊缝成形良好；在激光功率5-6kW，焊速1。8m/min,离焦量为-4mm时可以获得满意的成形和较为优良的综合性能，焊缝接头抗拉强度1600MPa，强度系数达到1。0，拉伸试验断口出现在熔合区，该区域硬度最低、组织最为复杂，焊缝组织为马氏体，热影响区组织为马氏体、屈氏体以及铁素体，总体性能达到了实际生产和使用的要求。

毕业论文关键词  高强钢  激光焊接  焊接性   组织性能

毕业设计说明书外文摘要

Title    Study of Fiber Laser Welding for High Strength Steel 

Abstract This study aims at the need for high quality joint of 6211 high strength steel in thin or medium thickness and designs the contrast experiment with the changes in three most significant parameters：power, welding speed and defocusing distance。 After a series of analysis such as joint appearance, X-ray detection, microstructure, micro-hardness, tensile strength, as well as XPS, property and characteristic of 6211 steel can be gained, meanwhile, this paper gets the relationship between the welding parameters and the performance。 Finally a suit of parameters used for a best joint was carried out。 Seen from the result of the experiment,6211 steel enjoys a disappointed weldability with a high carbon equivalent and serious disorder brittle organization。 However, laser welding can well satisfy the request of thin or medium thickness plates , which can generate a wonderful joint with satisfied performance with no defect at all, as long as a suitable parameter is determined。 Take 5 to 6kw in power,1。8m/min speed and -4mm in defocusing distance for example, the joint totally meets the needs。 Those joint have all withstood the tensile strength of around 1600MPa, with strength ratio of 1。0。  Fusion area boundary has the lowest hardness, where is still the source of crack。 As for the microstructure, weld seam is martensite, fusion zone is the mixture of martensite,troostite and ferrite。 In all, the joint is successful and achieves our request for manufacture and usage。

Keywords  6211 high strength steel ;fiber laser welding ; weldability; microstructure and property

目  录

1  引言 1

1。1  选题背景 1源-于,优Y尔-论,文.网wwW.yOueRw.com 原文+QQ752018,766

1。2  高强钢激光焊的技术现状 2

1。3  本次研究的目标以及内容 3

2 试验设备以及方法 4

2。1  焊接设备 4

2。2  试验方案 7

3 6211高强钢的激光焊接 9

3。1 焊前准备和焊接参数选择