本文選題：Q345船舶鋼 + 激光-電弧復(fù)合焊　； 參考：《南京理工大學(xué)》2016年碩士論文

【摘要】：激光焊在能量密度高,焊接速度快,焊縫深寬比大,熱影響區(qū)小,呈現(xiàn)窄的熱影響區(qū)和小的熱變形,而且焊接時(shí)無(wú)需真空。目前船舶行業(yè)普遍采用的是手工焊接,采用激光焊來(lái)提高焊接質(zhì)量、焊接智能化迫在眉睫。激光填絲焊和復(fù)合焊接技術(shù)可以降低裝配精度、改善焊縫冶金特性、提高接頭機(jī)械性能。本文針對(duì)9mm厚Q345船舶鋼進(jìn)行激光電弧復(fù)合焊、激光填絲焊工藝研究,為船舶鋼激光焊提供技術(shù)參考。激光填絲焊和復(fù)合焊需要調(diào)節(jié)焊接工藝參數(shù),包括送絲速度、離焦量、激光功率、光絲距、焊接速度、電流值等,來(lái)獲得良好質(zhì)量的焊縫。離焦量決定了熱影響區(qū)的大小。填絲焊光絲距需控制在-1 mm至+1 mm,而復(fù)合焊由于激光和電弧的共同作用,光絲距在2mm至3mm時(shí)成型良好。激光功率增大,熔深熔寬增大;焊接速度增大,熔深熔寬減小。這是因?yàn)榧す夤β屎秃附铀俣葲Q定了功率密度,從而決定了熔深熔寬。復(fù)合焊中的電流值在150 A到220 A之間,復(fù)合焊成型良好。填絲焊中,送絲速度也影響激光能量在熔化焊絲和促進(jìn)熔池中的分配。激光填絲焊和復(fù)合焊改善了自熔焊的錯(cuò)邊容限和間隙適應(yīng)性。填絲焊錯(cuò)邊容限為1.3 mm,間隙適應(yīng)值為0.9 mm;復(fù)合焊的錯(cuò)邊容限為1.8 mm,間隙適應(yīng)值為1.4 mm。激光填絲焊和激光電弧復(fù)合焊接在生產(chǎn)實(shí)際中有更好的應(yīng)用前景。傳統(tǒng)焊接方式中,Q345易產(chǎn)生氣孔和熱裂紋。由于激光焊線能量大,熱影響區(qū)小,冷卻速度快,經(jīng)過(guò)精密的焊前處理,在合理的工藝參數(shù)下,選用氬氧混合保護(hù)氣體,可以獲得無(wú)氣孔、無(wú)熱裂紋的焊縫。復(fù)合焊與填絲焊的接頭都是由焊縫區(qū)、熱影響區(qū)、母材而組成。對(duì)于復(fù)合焊,焊縫微觀組織由部分魏氏體和貝氏體組成；熱影響區(qū)有明顯的羽毛狀上貝氏體和板條馬氏體；熱影響區(qū)中的不完全結(jié)晶區(qū)有在晶界處重新形核長(zhǎng)大的趨勢(shì)。而填絲焊的組織相對(duì)與復(fù)合焊較為細(xì)小,因?yàn)樘罱z焊在單激光熱源作用下,熔池停留的時(shí)間較短。填絲焊、復(fù)合焊拉伸試樣均斷于母材；填絲焊和復(fù)合焊的顯微硬度均是母材小于熱影響區(qū),熱影響區(qū)小于焊縫區(qū)。填絲焊最大硬度為340 HV,比復(fù)合焊大6%左右；填絲焊焊縫的沖擊功為55J,比復(fù)合焊大12%。試樣正彎曲角度與背彎曲角度能達(dá)到180。。拉伸和沖擊斷口均分布有等軸韌窩,焊接接頭均為韌性斷裂。經(jīng)盲孔法測(cè)試的殘余應(yīng)力值均不高。
[Abstract]:Laser welding has high energy density, high welding speed, large ratio of weld depth to width, small heat affected zone, narrow heat affected zone and small thermal deformation, and there is no need for vacuum in welding. At present, manual welding is widely used in the shipbuilding industry. It is urgent to use laser welding to improve welding quality. Laser wire filling welding and composite welding technology can reduce the assembly accuracy, improve the metallurgical characteristics of weld and improve the mechanical properties of joints. In this paper, laser arc composite welding and laser wire filling welding for 9mm thick Q345 ship steel are carried out, which provides a technical reference for laser welding of ship steel. The welding parameters including wire feeding speed, defocusing, laser power, optical wire distance, welding speed, current value and so on need to be adjusted to obtain good quality weld seam by laser wire filling welding and composite welding, which include wire feeding speed, defocusing amount, laser power, optical wire distance, welding speed, current value and so on. The amount of defocus determines the size of the heat affected zone. The distance between filler wire and wire should be controlled between 1 mm and 1 mm, while the distance between 2mm and 3mm is well formed due to the combined effect of laser and arc. The laser power increases the penetration width increases and the welding speed increases and the penetration width decreases. This is because laser power and welding speed determine the power density, thus determining the penetration width. The current value in the composite welding is between 150 A and 220 A, and the composite welding is well formed. The feeding speed also affects the distribution of laser energy in the melting wire and the melting pool. Laser wire filling welding and composite welding can improve the tolerance and clearance adaptability of self-fusion welding. The error margin tolerance and clearance fitness of filler wire welding are 1.3 mm and 0.9 mm, respectively, and that of composite welding are 1.8 mm and 1.4 mm respectively. Laser wire filling welding and laser arc welding have better application prospect in production practice. In the traditional welding mode, Q345 is easy to produce porosity and hot crack. Due to the large energy of laser welding line, small heat affected zone and fast cooling rate, through precise pre-welding treatment and under reasonable technological parameters, the welding seam without porosity and heat crack can be obtained by selecting argon and oxygen mixed protective gas. The joint of composite welding and filler wire welding is composed of weld zone, heat affected zone and base metal. For the composite welding, the microstructure of the weld is composed of a part of Weieldite and bainite, the heat affected zone has obvious feathery upper bainite and lath martensite, and the incomplete crystallization zone in the heat affected zone has the tendency of renucleating at the grain boundary. The microstructure of filler wire welding is smaller than that of composite welding because the retention time of weld pool is shorter under the action of single laser heat source. The microhardness of filler wire welding and composite welding is smaller than heat affected zone and heat affected zone is smaller than weld zone. The maximum hardness of filler wire welding is 340 HVV, which is about 6% greater than that of composite welding, and the impact power of filler wire welding weld is 55 J, which is 12% larger than that of composite welding. The positive bending angle and the back bending angle of the sample can reach 180. The tensile fracture and impact fracture are equiaxed dimples, and the welded joints are ductile fracture. The residual stress measured by blind hole method is not high.
【學(xué)位授予單位】：南京理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：U671.8

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本文編號(hào)：1965210