本文選題：水下濕法焊接 + 微觀組織�。� 參考：《大連海事大學(xué)》2015年碩士論文

【摘要】：目前,水下濕法焊條電弧焊作為最經(jīng)濟(jì)實(shí)用的水下焊接方法應(yīng)用的最為廣泛。濕法水下焊接最常見的缺陷是氫致裂紋和焊縫成形差,而焊縫成形性較好的埋弧焊技術(shù)由于環(huán)境及設(shè)備的原因未能應(yīng)用于水下焊接。現(xiàn)有的水下焊條對(duì)藥皮的保護(hù)要求嚴(yán)格并且使用前需要去除引弧端的防水層。本文針對(duì)以上問(wèn)題,基于埋弧焊原理研制了多股同心藥芯水下焊條,通過(guò)在室溫下進(jìn)行陸上和水下平焊試驗(yàn),焊后對(duì)接頭組織進(jìn)行觀察和硬度測(cè)量,與現(xiàn)有的普通焊條THJ422和水下焊條TS202焊接接頭進(jìn)行對(duì)比,分析討論這種新型焊條的特點(diǎn)及確定最優(yōu)焊藥比的范圍。主要研究結(jié)果如下：1.在水下濕法焊接中,自制焊條電弧穩(wěn)定性稍低于TS202,藥芯焊絲數(shù)目增加,焊藥比減少,電弧穩(wěn)定性逐漸提高。在相同參數(shù)下,焊藥比減少會(huì)增加焊縫成形系數(shù),自制焊條與TS202的焊縫成形系數(shù)數(shù)值相差0.02-0.36。試驗(yàn)得出的最優(yōu)焊藥比范圍為70%～77%。2.與TS202相比,自制焊條的焊縫寬度增加1.1～2.2mm,熔深增加0.1～0.6mm。而在余高的數(shù)值上,自制焊條要稍低于TS202焊條。3.金相分析中,自制焊條隨著藥芯焊絲數(shù)目的增多,在焊縫中,組織內(nèi)的馬氏體減少;在過(guò)熱區(qū),粒狀貝氏體組織增加；在細(xì)晶區(qū),自制焊條的晶粒大小不均勻。對(duì)硬度曲線進(jìn)行分析,在焊縫區(qū),TS202的硬度值最高,平均硬度為338HV,自制焊條隨藥芯數(shù)目增加,焊縫區(qū)的硬度值由280HV下降到192HV,但是都高于母材硬度。焊接接頭最高硬度值出現(xiàn)在粗晶區(qū),數(shù)值變化無(wú)規(guī)律。4.藥芯焊絲數(shù)目增多,電流需適當(dāng)提高。焊條的長(zhǎng)度隨焊絲數(shù)目增多而減少,目的是在制造過(guò)程中增加焊藥的致密性,減少氣孔缺陷。
[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.
【學(xué)位授予單位】：大連海事大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：U671.82

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相關(guān)期刊論文 前2條

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本文編號(hào)：2093813