多股同心药芯水下焊条的研制

发布时间：2018-07-03 13:29

本文选题：水下湿法焊接 + 微观组织　；参考：《大连海事大学》2015年硕士论文

【摘要】：目前,水下湿法焊条电弧焊作为最经济实用的水下焊接方法应用的最为广泛。湿法水下焊接最常见的缺陷是氢致裂纹和焊缝成形差,而焊缝成形性较好的埋弧焊技术由于环境及设备的原因未能应用于水下焊接。现有的水下焊条对药皮的保护要求严格并且使用前需要去除引弧端的防水层。本文针对以上问题,基于埋弧焊原理研制了多股同心药芯水下焊条,通过在室温下进行陆上和水下平焊试验,焊后对接头组织进行观察和硬度测量,与现有的普通焊条THJ422和水下焊条TS202焊接接头进行对比,分析讨论这种新型焊条的特点及确定最优焊药比的范围。主要研究结果如下：1.在水下湿法焊接中,自制焊条电弧稳定性稍低于TS202,药芯焊丝数目增加,焊药比减少,电弧稳定性逐渐提高。在相同参数下,焊药比减少会增加焊缝成形系数,自制焊条与TS202的焊缝成形系数数值相差0.02-0.36。试验得出的最优焊药比范围为70%～77%。2.与TS202相比,自制焊条的焊缝宽度增加1.1～2.2mm,熔深增加0.1～0.6mm。而在余高的数值上,自制焊条要稍低于TS202焊条。3.金相分析中,自制焊条随着药芯焊丝数目的增多,在焊缝中,组织内的马氏体减少;在过热区,粒状贝氏体组织增加；在细晶区,自制焊条的晶粒大小不均匀。对硬度曲线进行分析,在焊缝区,TS202的硬度值最高,平均硬度为338HV,自制焊条随药芯数目增加,焊缝区的硬度值由280HV下降到192HV,但是都高于母材硬度。焊接接头最高硬度值出现在粗晶区,数值变化无规律。4.药芯焊丝数目增多,电流需适当提高。焊条的长度随焊丝数目增多而减少,目的是在制造过程中增加焊药的致密性,减少气孔缺陷。
[Abstract]:At present, the underwater wet electrode arc welding is widely used as the most economical and practical underwater welding method. The most common defects of wet underwater welding are hydrogen induced cracks and poor weld forming. The submerged arc welding technology with good weld formability can not be used in underwater welding because of the environment and equipment. The existing underwater electrode has strict requirements for coating protection and need to remove the water-proof layer at the arc end before use. In order to solve the above problems, based on the principle of submerged arc welding, a series of concentric flux-cored underwater welding rods are developed. The joint microstructure and hardness are observed and measured after welding through overland and underwater flat welding tests at room temperature. Compared with the existing welding joints of THJ422 and TS202, the characteristics of the new electrode and the range of optimum flux ratio are analyzed and discussed. The main results are as follows: 1. In underwater wet welding, the arc stability of self-made electrode is slightly lower than that of TS202, the number of flux-cored wire increases, the flux ratio decreases, and the arc stability increases gradually. Under the same parameters, the weld forming coefficient will be increased by reducing the flux ratio, and the difference of weld forming coefficient between the self-made electrode and TS202 is 0.02-0.36. The optimum solder flux ratio obtained by the test is 70% 77. 2. Compared with TS202, the weld width and penetration depth of self-made electrode were increased by 1.1 ~ 2.2mm and 0.1 ~ 0.6mm. In the remaining high value, the self-made electrode is slightly lower than TS202 electrode. 3. In metallographic analysis, the martensite in the weld decreases with the increase of flux cored wire number, the granular bainite structure increases in the superheated zone, and the grain size of the self-made electrode is not uniform in the fine grain zone. By analyzing the hardness curve, the hardness value of TS202 in weld zone is the highest, the average hardness is 338HV.The hardness of welding rod decreases from 280 HV to 1921 HVwith the increase of flux core number, but all of them are higher than base metal hardness. The maximum hardness value of welded joint appears in coarse crystal region, and the numerical value change is irregular. 4. The flux cored wire number increases, the current needs to increase appropriately. The length of electrode decreases with the increase of the number of wires. The purpose is to increase the density of welding flux and reduce the porosity in the manufacturing process.
【学位授予单位】：大连海事大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U671.82

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