摘要:厚板焊接结构广泛运用与海工制造、大型钢结构以及核电建设等工程领域。厚板结构的焊接往往存在焊接道数多，焊接效率低，焊后残余应力大等问题。解决问题的思路是采用开窄间隙坡口的方式减少填充量，同时选用高能量密度的热源进行焊接。

本文针对厚板超窄间隙激光填丝焊焊接工艺进行了研究。通过平板堆焊及坡口内工艺试验优化了厚板焊接的工艺参数，设计了100mmQ345E超窄间隙坡口并成功进行了焊接。焊后利用光学显微镜、自动硬度仪、拉伸试验机和冲击试验机分析了接头的组织和性能。结果表明：采用超窄间隙激光填丝焊的方法并选取优化的焊接工艺参数焊接100mmQ345E厚板对接接头，焊接道数共37道，焊后成形良好，无气孔、裂纹和未熔合等缺陷。激光填丝焊焊缝组织主要为针状铁素体，粒状贝氏体和珠光体，表层焊道热影响区的粗晶区产生板条状马氏体。拉伸试样均断在母材，接头的横向侧弯试验表明接头无侧壁未熔合缺陷。冲击试验满足标准要求。接头的最高硬度出现在表层焊道的热影响区，为440HV。

通过对焊接过程中动态变形的检测进行施焊顺序的调整，控制工件最终的角变形量为3′42.58″，表面平面度达到0.398mm。与窄间隙埋弧焊工艺将比，超窄间隙激光填丝焊填充量减少87%，焊接效率提高31%。

关键词：厚板结构；激光填丝焊；超窄间隙坡口；工艺试验；组织性能；

Abstract:Thick plates were widely used at marine manufacturing, steel structure building, nuclear power construction and other engineering fields. There were some problems in the welding of the thick plates structure, such as too many welding channels, low welding efficiency and large residual stress after welding. The solution was to use narrow gap grooves to reduce the amount of filling. Chosing the heat sources with high energy density was also avaliable.

The ultra-narrow-gap laser welding with filler wire of thick plates was studied in this paper. The process parameters of thick plate welding were optimized by plate surfacing and groove test. A 100mm Q345E ultra narrow groove was designed and successfully welded. Then the optical microscope, automatic hardness tester，tensile testing machine and impact testing machine were used to test the microstructure and mechanical properties.

Results showed that the optimized process parameters could be used in welding 100mmQ345E thick plate butt joints, there were 37 beads in total. No defects were found in the joint, such as pores, crack and lack of fusion. The joint is composed of five welding seam. The microstructure of weld joint consisted of acicular ferrite, granular bainite and pearlite,  but  the  microstructure  in  coarse  grain  heat  affected  zone  was  lath martensite. The tensile samples broke in the base metal. Lack of fusion was not found through the side bending test of the joint. The impact test meets the standard requirements. The highest microhardness of the weld appeared in the heat affected zone of the weld surface. And it reached to 440 HV.

Adjusting the welding order through the the dynamic deformation of workpiece ,as a result, the final deformation of the workpiece was 3'42.58 " and the surface flatness was 0.398mm. Compared with narrow gap submerged arc welding, filling volume of the ultra-narrow-gap laser reduced by 87% and welding efficiency increased by 31%.

Keywords: Thick plate ; Laser welding with filler wire; Ultra-narrow-gap; Technics text; Microstructures and properties;

目录

第一章绪论 1

1.1课题背景及意义 1

1.2厚板焊接的方法 1

1.3窄间隙焊接方法在厚板中的应用