發(fā)布時間：2018-04-26 02:41

  本文選題：7449鋁合金 + 激光電弧復(fù)合焊��； 參考：《中南林業(yè)科技大學(xué)》2017年碩士論文

【摘要】：7449鋁合金是由法國Alcan公司研制生產(chǎn)的新型Al-Zn-Mg-Cu-Zr系合金,具有較高的強(qiáng)度、斷裂韌性及抗疲勞裂紋擴(kuò)展能力,已應(yīng)用在Air Bus公司最新研發(fā)的民用客機(jī)A350上,但國內(nèi)外關(guān)于7449鋁合金的激光電弧復(fù)合焊接頭的性能方面的研究工作很少。論文在大飛機(jī)用鋁合金研究項目背景下,以7449鋁合金薄板為實驗研究對象,借助金相顯微鏡(OM)、掃描電子顯微鏡(SEM)等微觀組織分析手段,并通過顯微硬度測試、拉伸性能測試、晶間腐蝕實驗和剝落腐蝕實驗等方法,探討并研究了激光電弧復(fù)合焊工藝及焊后熱處理工藝(固溶處理、單級時效)對7449鋁合金激光電弧復(fù)合焊接頭組織及性能的影響,并取得了如下主要研究成果:(1)在激光束偏轉(zhuǎn)軸線角度10°與電弧焊槍旁軸復(fù)合、15 L/min的高純氬氣作為保護(hù)氣體、電弧焊槍與母材的夾角為54°及光絲間距為3mm等條件下,7449鋁合金較優(yōu)的激光電弧復(fù)合焊的工藝參數(shù)為:激光功率為2.3 KW,焊接速度為40mm/s,離焦量為0mm,送絲速度為7 mm/s。此時復(fù)合焊接頭的抗拉強(qiáng)度為256.73 MPa,延伸率為2.87%,焊縫的硬度值為112.75 HV。接頭各區(qū)域的硬度值從焊縫區(qū)、熔合區(qū)到熱影響區(qū)逐漸增大。(2)對7449鋁合金激光電弧復(fù)合焊接頭進(jìn)行475℃/1h固溶處理后,抗拉強(qiáng)度和延伸率分別為430.70 MPa、3.80%,焊縫硬度為117.38 HV。與固溶處理前相比,抗拉強(qiáng)度提高了 67.76%,延伸率增大了 32.40%,硬度提高了 4.11%。(3)對7449鋁合金激光電弧復(fù)合焊接頭進(jìn)行120℃/24h單級時效處理后,抗拉強(qiáng)度和延伸率分別為542.90 MPa、3.96%,焊縫硬度為140.65 HV,比固溶處理后的接頭分別提高了 26.05%、4.0%和19.82%。熱影響區(qū)硬度水平恢復(fù)到與母材相當(dāng)。復(fù)合焊接頭的塑性略有恢復(fù)。(4)7449鋁合金激光電弧復(fù)合焊接頭固溶處理前、后的抗腐蝕能力基本一致,焊縫區(qū)、熱影響區(qū)、母材區(qū)的抗腐蝕能力依次減小;而單級時效后,焊縫區(qū)、熱影響區(qū)、母材區(qū)的抗腐蝕能力依次提高。焊后熱處理對接頭的晶間腐蝕性能和剝落腐蝕性能的影響是相同的。
[Abstract]:7449 aluminum alloy is a new type of Al-Zn-Mg-Cu-Zr alloy developed and produced by Alcan Company of France. It has high strength, fracture toughness and anti-fatigue crack propagation ability. It has been applied to the newly developed A350 of Air Bus Company. However, there is little research on the properties of 7449 aluminum alloy laser arc composite welding joint at home and abroad. Under the background of the large aircraft aluminum alloy research project, taking 7449 aluminum alloy thin plate as the experimental object, by means of metallographic microscope, scanning electron microscope (SEM) and other means of microstructure analysis, microhardness test, tensile property test, etc. The effects of laser arc composite welding process and post welding heat treatment (solid solution treatment, single stage aging) on the microstructure and properties of laser arc composite welding joint of 7449 aluminum alloy were discussed and studied by means of intergranular corrosion test and exfoliation corrosion test. The main research results are as follows: (1) High purity argon, which is composed of laser beam deflection axis angle of 10 擄and arc welding torch side axis for 15 L/min, is used as protective gas. When the angle between the arc welding torch and the base metal is 54 擄and the optical wire spacing is 3mm, the optimum parameters of laser arc composite welding are as follows: laser power is 2.3 KW, welding speed is 40 mm / s, defocus is 0 mm, wire feeding speed is 7 mm / s. The tensile strength of the joint is 256.73 MPA, the elongation is 2.87 and the hardness of the weld is 112.75 HV. The hardness of 7449 aluminum alloy laser arc composite welding joint increased gradually from weld zone, fusion zone to heat affected zone. The tensile strength and elongation of 7449 aluminum alloy laser arc composite welding joint were 430.70 MPA / 1 h and 117.38 HV, respectively. The tensile strength, elongation and hardness of 7449 aluminum alloy laser arc composite welding joint were increased by 67.76%, 32.40% and 4.11% respectively, compared with those before solution treatment. After 120 鈩，

本文編號：1804142