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1、摘要摘要 “西气东输”工程选用的 X70 管线钢，在焊接过程中产生残余应力及各种负作 用，改变了其组织和耐蚀性能。焊后热处理具有消除残余应力、改善组织及提高耐 蚀性能的作用，我们对部分材料进行了焊后热处理，并且采用高温回火工艺及不同 的回火温度。 本文通过金相观察及拉伸试验来探讨焊后热处理对 X70 管线钢组织的影响，通 过失重法来分析焊后热处理对 X70 管线钢耐蚀性的影响。 金相观察结果分析表明：焊后热处理前后的显微组织无论焊缝、母材还是热影 区都是不同的，组织明显细化，利于强韧性的组织增加。不同回火温度的焊后热处 理也存在差别，不过这种差别较前者明显减弱，但是仍然改善了材料的组织，使材
2、料强韧性得到进一步提高。 拉伸试验结果分析表明：焊后热处理提高了材料的抗拉强度和塑韧性，并且在 都进行焊后热处理的材料中随着回火温度的提高屈服强度和塑韧性也得到了提高， 但是随回火温度的提高材料的抗拉强度略微降低，可知焊后热处理提高了材料的强 韧性，回火温度的提高能够进一步改善材料的强韧性。验证了金相分析的结论。 失重法结果分析表明：焊后热处理后材料的腐蚀重量指标和深度指标都相应的 降低，说明焊后热处理提高了材料的耐蚀性。并且回火温度的提高也使得这两项指 标降低，说明随焊后热处理中回火温度的提高材料的耐蚀性增强。 关键词关键词: X70 钢；焊后热处理；组织；耐蚀性 西南石油大学本科毕业论文
3、II ABSTRACT West-East Gas pipeline project selected X70 pipeline steel. in the process of welding,X70 pipeline steel brings residual stress and various negative effects,as a result changes its organization and corrosion resistance. PWHT can eliminate residual stress , improve the organization and en
4、hance the corrosion resistance, we carried out PWHT in some of the material and adopt high temperature tempering process and different tempering temperature. In this paper, metallographic observation and tensile test to investigate PWHT on the impct of X70 pipeline steel organizations, through the w
5、eight-loss method to analyze PWHT on impct of X70 pipeline steel corrosion resistance. The observations of metallographic analysis showed that: the before and after PWHT whether the microstructure of weld, base metal or heat affected zone is different, obviously refining organization, Increasing in
6、the Organization which will help to increase the strength and toughness. Under different tempering temperature in PWHT also exist differences,but this difference decreased over the former, but still improved the organization of material, so that the material strength and toughness to be further impr
7、oved. Analysis in the tensile test results showed that: PWHT improved the tensile strength and plastic material toughness, with increasing in tempering temperature , the materials which have carried out PWHT also improved the yield strength and toughness, However, with increasing the tempering tempe
8、rature, tensile strength in the materials is slightly lower.we can see PWHT to improve the material strength and toughness, and with increasing the tempering temperature in PWHT further improve the material strength and toughness. validating the conclusions in the metallographic analysis. The result
9、s in the weight-loss method show that: after PWHT, depth indicators and weight indicators in the Corrosion Materials are the corresponding lower,which shows that post-weld heat treatment improved the corrosion resistance in materials.with Increasing the tempering temperature, these two indicators al
10、so makes to reduce,which shwos that With increasing the tempering temperature in PWHT,the corrosion resistance in the materials also enhances. Keywords: X70 pipeline steel；PWHT；microstructure；corrosion resistance 目录目录 西南石油大学本科毕业论文 IV 摘要 .I ABSTRACT.II 1 绪论.1 1.1 研究背景及目的.1 1.2 国内外研究状况.2 1.3 研究内容.3 1.4 研究方法.3 2 实验材料及方法.4 2.1 实验材料.4 2.2 实验方法.4 2.2.1 焊后热处理.4 2.2.2 金相实验.5 2.2.3 拉伸试验.5 2.2.4 腐蚀实验.6 3 实验结果与分析.8 3.1 金相实验结果.8 3.2 拉伸试验
