酸性介质碳钢及低合金钢管道热丝TIG焊接工艺研究

发布时间：2018-04-22 17:24

  本文选题：热丝TIG + 焊接工艺　； 参考：《西南石油大学》2017年硕士论文

【摘要】：热丝TIG焊拥有优于一般手工钨极氩弧焊的焊接质量和自动化焊接带来的高效率,研发出一套耐酸性介质腐蚀的碳钢及低合金钢管道热丝TIG焊接工艺技术,作为酸性气田地面建设的重要技术储备,满足工程建设实际生产需求。本文采用振动送丝半自动热丝TIG焊接设备,试验满足酸性介质服役条件的L245、L360级别钢管进行焊接接头设计、焊接参数开发、焊接工艺措施制定、焊接接头力学性能试验和焊缝组织分析、焊接接头耐蚀性能研究,并对焊接质量控制措施和焊接工效进行了分析。通过以上分析研究得到以下结论:选用V型有间隙坡口时,钝边高度和对口间隙是控制根部成型的主要参数,适当增加钝边高度有助于提高焊缝根部的电流承载力,将间隙控制在2.5±0.2mm有助于提高焊接速度和根部成型。选用U型无间隙坡口时,钝边高度是控制无间隙对口焊缝根部成型的关键,钝边高度宜控制在2.5至3.0mm。将V型坡口角度设计为60°±5°,U型坡口角度设计24°±5°,便于根焊操作。大坡口多层多道焊接能显著提高冲击韧性,所有试验焊缝硬度均满足验收要求,当热丝TIG焊最大填盖焊接线能量从1.22KJ/mm降低至0.99KJ/mm,坡口角度从24°加大至60℃,焊缝硬度逐渐降低。焊缝金属组织为F+P,随线能量的升高和单道焊缝厚度变大逐渐出现M/A组元,组织均匀度逐渐变差。热丝TIG焊缝组织较手工钨极氩弧焊+焊条电弧焊组织均匀度较好,晶粒更致密,非金属夹杂物含量更低。热丝TIG焊缝试样满足90%实际屈服强度应力条件下的抗硫化氢应力腐蚀开裂要求和抗氢致开裂要求。手工钨极氩弧焊+焊条电弧焊的焊缝自腐蚀电流密度为7.1829×10~(-5),热丝TIG焊接的焊缝自腐蚀电流密度为4.8473×10~(-5),热丝TIG焊缝耐电化学腐蚀性能优于手工钨极氩弧焊+焊条电弧焊焊缝。未焊透、内凹是焊缝根部主要缺陷,根部焊接时应控制钨极与熔池间距,钨极与焊道夹角成约45°至60°,控制合理的坡口钝边尺寸和电弧吹力,保证熔池流动性和熔透能力是避免根部缺陷的主要措施。未熔合是热焊及填充焊主要缺陷,应注意焊道成型,采用多道焊接方式及减少单层焊接厚度是避免未熔合缺陷的主要措施。采用U型坡口时比V形坡口焊接效率高100%至150%,填盖焊接效率高38%至40%。采用V型坡口时,热丝TIG的焊材耗量比手工焊减少约45%,焊接效率高约15%,在采用U型坡口时比采用氩电焊接的焊材减少约66%,焊接效率高约42%。
[Abstract]:Hot wire TIG welding has better welding quality than manual TIG welding and high efficiency brought by automatic welding. A set of hot wire TIG welding technology for acid medium corrosion resistant carbon steel and low alloy steel pipeline has been developed. As an important technical reserve for surface construction of acid gas field, it meets the actual production demand of engineering construction. In this paper, the semi-automatic hot-wire TIG welding equipment for vibrating wire feeding is used to test the welding joint design, welding parameter development and welding process measures of L245 and L360 grade steel pipe, which meet the service conditions of acid medium. The mechanical property test, weld microstructure analysis and corrosion resistance of welded joint were studied. The welding quality control measures and welding efficiency were analyzed. The conclusions are as follows: when V type groove with clearance is selected, the height of the obtuse edge and the corresponding gap are the main parameters to control the forming of the root, and the proper increase of the height of the obtuse edge is helpful to improve the current bearing capacity of the weld root. Controlling the gap at 2. 5 卤0.2mm is helpful to improve the welding speed and the forming of the root. When U type gap free groove is selected, the height of the blunt edge is the key to control the root forming of the weld seam without clearance, and the height of the obtuse edge should be controlled between 2.5 and 3.0 mm. The V-groove angle is designed to be 60 掳卤5 掳U groove angle 24 掳卤5 掳, which is convenient for root welding. The impact toughness can be significantly improved by multi-layer and multi-pass welding of large groove, and the hardness of all test welds can meet the acceptance requirements. When the maximum welding line energy of hot wire TIG welding decreases from 1.22KJ/mm to 0.99KJ / mm and the groove angle increases from 24 掳to 60 鈩，

本文编号：1788207