管道闪光对焊在线监测系统及焊接工艺研究

发布时间：2019-01-05 06:11

【摘要】：闪光对焊技术属于电阻压力焊的一种,因其自动化程度高、焊接质量好、高效且可焊金属范围广等优点,在油气输送、石油化工、海洋工程、能源电力等行业的应用前景极为广阔。国内已将其广泛应用于钢轨焊接,但针对管道的闪光对焊国内尚无实际应用,中国乌克兰巴顿焊接研究院率先从国外引进了K584Ch管道闪光对焊设备,在国内首次针对把闪光对焊技术应用于管道的焊接开展了大量的研究工作。本文首先针对K584Ch管道闪光对焊设备利用图形化编程语言LabVIEW开发设计管道闪光对焊在线监测系统,实现了闪光对焊工艺参数的采集、显示与存储,通过采集闪光对焊过程中的焊接电流、焊接电压、位移和压力信号,分析闪光对焊过程工艺参数对焊接质量的影响。本文针对X65管线钢和20G锅炉钢分别进行了正交试验和单因素试验。X65管线钢正交试验是以激发闪光阶段进给量Sj、激发闪光阶段焊接电流阀值Ⅰ、稳定闪光阶段进给量Sw和加速闪光阶段的进给速度V为试验因素,根据以往的工艺经验手册和试焊结果,每因素确定三个水平,不考虑各因素间的交互关系,按照L9(34)正交表进行9次正交试验和1次优化验证试验。20G锅炉钢单因素试验是以加速闪光阶段的进给速度V为参变量,取三个水平,研究加速闪光阶段的进给速度V对焊接质量的影响。两组试验均以接头力学性能作为试验考核指标,选出合理工艺方案,实现了对焊接工艺参数的优化。通过对K584Ch管道闪光对焊在线监测系统采集到的焊接电流数据进行分析,可以初步判定焊接质量的优劣,且判定结果与力学性能检测和金相组织分析的结果基本保持一致,在一定程度上为管道闪光对焊的工艺优化提供了支持。通过力学性能检测,发现管道闪光对焊接头的强度和硬度基本都能满足使用需求,但塑性和韧性较差,管道内壁180°位置存在大焊瘤使该位置处硬度下降。管道闪光对焊接头的断裂多为脆性断裂,有明显的金属光泽,刻槽锤断试样的断口呈现出河流花样的解理断裂形貌,接头内部普遍存在灰斑缺陷,且属于硅酸盐夹杂型灰斑。对20G锅炉钢对焊接头金相分析,发现其焊缝宽度约为0.7mm,焊缝显微组织为粗大块状铁素体、魏氏组织铁素体和少量珠光体,存在脱碳现象,这种组织导致了焊缝硬度和强度的下降、韧性欠佳。热影响区较宽,约为24mm,粗晶区的魏氏组织较为严重,较为严重的魏氏组织导致材料的韧性(冲击功)明显下降。
[Abstract]:Flash butt welding is a kind of resistance pressure welding, because of its high degree of automation, good welding quality, high efficiency and wide range of weldable metals, it is widely used in oil and gas transportation, petrochemical, offshore engineering, etc. The application prospect of energy power and other industries is extremely broad. It has been widely used in rail welding in China, but there is no practical application in China for pipeline flash butt welding. China Button Welding Research Institute of Ukraine first imported K584Ch pipe flash butt welding equipment from abroad. For the first time in China, a lot of research work has been carried out on the application of flash butt welding technology in pipeline welding. In this paper, the on-line monitoring system of pipeline flash butt welding is developed by using graphical programming language LabVIEW for K584Ch pipeline flash butt welding equipment. The acquisition, display and storage of technological parameters of flash butt welding are realized. By collecting welding current, welding voltage, displacement and pressure signals during flash butt welding, the influence of process parameters on welding quality is analyzed. In this paper, orthogonal test and single factor test are carried out for X65 pipeline steel and 20G boiler steel respectively. The orthogonal test of X65 pipeline steel is based on stimulating flash stage feedrate Sj, to stimulate flash stage welding current threshold. The feed rate Sw of stable flash stage and feed velocity V of accelerated flash stage are the experimental factors. According to the previous process experience manual and welding results, three levels are determined for each factor, without considering the interaction between each factor. According to the orthogonal table of L9 (34), nine orthogonal tests and one optimized verification test were carried out. The single-factor test of 20G boiler steel was based on the feed velocity V of accelerating flash stage as parameter variable, taking three levels. The effect of feed speed V in accelerating flash stage on welding quality was studied. The mechanical properties of the joints were taken as the test index in both groups, and the reasonable process scheme was selected to optimize the welding process parameters. Through the analysis of welding current data collected by K584Ch pipeline flash butt welding on-line monitoring system, the quality of welding can be preliminarily determined, and the result is basically consistent with the results of mechanical property test and metallographic analysis. To some extent, it provides support for the process optimization of pipeline flash butt welding. It is found that the strength and hardness of the pipe flash butt welded joint can meet the requirement of application, but the ductility and toughness are poor, and the hardness of the pipe is decreased due to the existence of a large welding nodule at 180 掳position of the inner wall of the pipe. The fracture of the pipe flash butt welding joint is mostly brittle and has obvious metallic gloss. The fracture surface of the groove hammer fracture specimen presents the cleavage fracture appearance of the river pattern, and there is a common gray spot defect in the joint, and it belongs to silicate inclusion type gray spot. By metallographic analysis of butt welded joints of 20G boiler steel, it is found that the weld width is about 0.7 mm, the microstructure of the weld is coarse block ferrite, the ferrite of Weiss structure and a small amount of pearlite exist decarbonization phenomenon. This microstructure leads to a decrease in the hardness and strength of the weld and poor toughness. The heat affected zone is wider, about 24mm. The Weiss structure in the coarse crystal region is more serious, and the toughness (impact work) of the material decreases obviously because of the more serious Weichen structure.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG457.11

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