摘要不锈钢与碳钢的复合管因为同时具有两种钢的特性有着价格低廉，并且耐腐蚀性好、适用性广的特点而被广泛应用于石油输送、西气东输、以及许多其他的民用工程，因此具有很高的研究价值。本文先将对以往普通焊接方法下的复合管试样进行分析试验研究，发现了热影响区焊缝的硬度梯度，分析了其中的原因是由于受到热输入的影响，不锈钢中的Cr元素因为吸引C元素而导致C的转移，进而使焊接接头熔合区的C元素分布产生梯度分布。为了解决热输入过大的不良因素，本次试验最终决定采取热输入量小的工艺如：选取使用大坡口，以减少热输入，采用手工TIG焊、309L不锈钢焊丝进行封焊，手工TIG焊、309L不锈钢焊丝打底，CO2 气体保护焊、316L不锈钢焊丝过渡焊，CO2 气体保护焊、H08A焊丝进行填充盖面焊。完成了对复合钢管316L不锈钢和20号碳钢的对接。并且在蔡氏光学金相显微镜、数显维氏显微硬度计等仪器的帮助下对焊接接头进行了微观组织成分分析和力学性能变化分析。87007

通过多组实验的对比比较，结果发现了在对复合管进行焊接时，减少热输入量可以有效地降低焊缝熔合区的硬度的梯度变化。为以后焊接复合管提供了科学的参考依据。

毕业论文关键词 不锈钢复合管；热输入；焊缝组织；力学性能

Abstract Stainless steel clad pipe is widely used in many areas such as oil pipeline, west-east gas, and many other civil engineering because it has the characteristics of two kinds of steel at the same time，such as，the price of stainless steel clad pipe is low, the corrosion resistance is good and it is wide applicability。 The body of the article is going to analyze the composite pipes which in the traditional weld methods we usually used before, to my surprise, I found that the hardness gradient of the weld seam in the heat-affected zone was unusual。 With further research, I found that the heat affected zone of weld hardness gradient, and analyzed the reason is the effect of heat input, stainless steel because of the Cr elements attract elements lead to transfer of C, and C and C elements distribution in welding joint fusion district produce gradient distribution it was so more heat input to cause that result, so we should adopt one technology with little heat input in our experiment, like manual welding, decided to take a small amount of heat input process such as: the manual TIG welding, 316L stainless steel welding wire, CO2 gas shielded arc welding, the transition of 316L stainless steel wire welding, CO2 gas shielded welding, filling covering H08A welding wire for welding。 Completed the butt joint of composite pipe of 316L/20 steel。 And in optical metallographic microscope, vickers microhardness tester, the help of instrument on the weld joint microstructure composition analysis and mechanical property analysis。

The results showed that the composite tube welding, reduce heat input can effectively reduce the hardness of the weld bond of ups and downs。 Provide a scientific reference for welding pipe。

Keyword Stainless steel; Hot-input; Microstructure of the weld ; Mechanical property

目录

第一章 绪论 1

1。1  选题背景及意义 1

1。2  复合钢管的介绍 1

1。3  国内外复合管的发展现状 3

1。3。1  国外复合管的发展现状 3

1。3。2  国内复合管的发展现状 3

1。4  焊接材料的发展 4

1。5  研究内容 5

第二章 复合管的焊接性