论文总字数：20681字

摘 要

奥氏体不锈钢的焊接性能优异，但在焊接的过程中或焊接完成后会出现一些问题。例如：焊接热裂纹、焊缝的晶间腐蚀、焊缝未熔合与未焊透、焊缝氧化、表面气孔和焊瘤等，尤其是焊接后的耐蚀性能变化。

本文根据工程实际的焊接损伤案例，运用不锈钢的焊接冶金原理，对上述焊接损伤缺陷进行分类整理，逐个进行分析归纳，寻找出焊接损伤的规律，并且拟从焊接冶金这一角度出发，研究奥氏体不锈钢在焊接过程中，和金属学有关的一系列问题。

焊接的时候通入保护惰性气体（如氩气）或者使用高温抗氧化剂（液体或涂料）均可以有效减少焊接表面过氧化的现象，动态调整焊缝中的δ铁素体的含量至一个合适比例，就能够有效地抑制焊接裂纹，δ铁素体的含量与熔合比、焊条以及电流均有较大的关联。其中，电流越大，熔合比的值也越大。国标规定的δ铁素体含量在5-8%，实验显示δ铁素体的含量在3-10%就能保证不出现焊接裂纹。选择V型坡口能使焊缝中δ铁素体的含量得到保证，故能将开裂风险降到最低。

关键词：奥氏体 焊接缺陷 晶间腐蚀 熔合比

Discussion on Alloying of Austenitic Stainless Steel Weld

ABSTRACT

Austenitic stainless steel welding performance is excellent, but in the welding process or welding is completed after some problems. For example: welding hot cracks, weld intergranular corrosion, welds are not fused and not welded, weld oxidation, surface pores and welding, etc., especially after welding corrosion resistance changes.
In view of this situation, the analysis of austenitic stainless steel weld in a series of problems, and from the perspective of welding metallurgy, austenitic stainless steel in the welding process, and metal a series of problems related to Reduce the use of the process left a series of problems, such as: corrosion cracking risk, joint corrosion resistance changes, hot cracks and so on.
When welding, it is possible to effectively reduce the content of δ ferrite in the weld by adjusting the amount of inert gas (such as argon) or the use of high temperature antioxidant (liquid or paint) to effectively reduce the surface oxidation of the weld surface to a suitable ratio , It can effectively inhibit the welding crack, δ ferrite content and the fusion ratio, electrode and current are relatively associated. Among them, the greater the current, the greater the value of fusion ratio. GB of the provisions of the δ ferrite content of 5-8%, experiments show that δ ferrite content of 3-10% can guarantee that no welding cracks. The choice of V-shaped groove to ensure that the weld δ ferrite content is guaranteed, it can minimize the risk of cracking.

Key word: Austenite；Welding defects；Intergranular corrosion；fusing ratio

目 录

摘要……………………………………………………..………………Ⅰ

ABSTRACT………………………………………….…………………Ⅱ

第一章 绪论………………………………………….............…………1

1.1课题的研究背景及意义………………………………….…….…….…1

1.2奥氏体不锈钢的焊接性分析…………………………………........……1

1.2.1 奥氏体不锈钢焊接接头的耐蚀性……………….....…………………2

1.2.2 奥氏体不锈钢的焊接热裂纹…………………………....……………4

1.2.3 析出现象……………………………................................…………5

1.2.4 低温脆化……………………..……………..............................……5

1.3 奥氏体不锈钢的焊接工艺特点…….……………………...….…………5

1.3.1 焊接方法的选择…………..……………………....................………5

1.3.2 操作工艺……………………….……….............................…..……6

1.4本课题的研究内容及其方法………………………….......………..……6

第二章 工程中奥氏体不锈钢的焊接现象……………....…………7

2.1咬边案例………………………………………..............……….……7

2.2裂纹（开裂）实际案例………………............................…………..…9

2.3过氧化实例…..………………………...............................…………11

2.4未熔合或未焊透实例………………………………...………….……13

2.5表面气孔实例……………………………………………....…………15

2.6焊瘤实例………………………………………………....…………17

2.7奥氏体不锈钢焊缝中的腐蚀现象………………………………………18

2.8焊接损伤的小结………………………………………………………20

第三章 焊接冶金和焊接工艺对实际问题的影响……………………20

3.1 焊缝成型表面形状和尺寸不符合要求….………………..……………21

3.1.1焊缝成型表面形状和尺寸不符合要求的原因…………………………21

3.1.2防止焊缝成型表面形状和尺寸不符合要求的措施.……………………21

3.2焊接裂纹………..………………...............…………………………21

3.2.1热裂纹的形成………………..…...............…………………………21

3.2.2影响奥氏体不锈钢焊接热裂敏感性的因素…...………………………23

3.2.3防止焊接热裂纹的措施……………..………………………………23

3.3咬边………………………………………………..…………………23

3.3.1咬边产生的原因…………………………………….………………23

3.3.2 防止咬边的措施…………………….………..……………………24

3.4 未熔合和未焊透………………...……………………………………24

3.4.1 未熔合和未焊透的原因..………….......................…………………24

3.4.2防止未熔合和未焊透的措施…………………..…..…………………24

3.5表面气孔………………………..…....................……………………25

3.5.1表面气孔产生的原因…………..…....................……………………25

3.5.2防止表面气孔产生的措施...………....................……………………25

3.6焊瘤……………..…………………....................……………………25

3.6.1焊瘤产生的原因…………………....................……………………25

3.6.2防止焊瘤产生的措施..……………....................……………………27

3.7综合考虑.. …………………………....................……………………26

3.8 焊接工艺分析...……………………....................……………………27

第四章 结论…………………................................……………………29

参考文献…………………...................................……………………30

致谢………..…………………................................……………………31

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