鑄造鎂合金A-TIG補(bǔ)焊工藝研究
發(fā)布時間：2019-03-13 18:54
【摘要】：鎂合金因其具有優(yōu)良特性,被廣泛應(yīng)用于航空航天、汽車、電子通訊等領(lǐng)域,通過鎂合金零部件的使用可以有效地實現(xiàn)輕量化目標(biāo)。由于變形鎂合金生產(chǎn)成本比較高,目前工業(yè)應(yīng)用的鎂合金以鑄造件為主,鎂合金在鑄造過程中極易出現(xiàn)各種類型的缺陷,如氣孔、裂紋等,或者機(jī)械加工和運輸過程中產(chǎn)生的缺陷而使鑄件成為不合格品,不僅造成了材料的極大浪費而且影響產(chǎn)品的交付使用,所以對鑄件缺陷的修補(bǔ)具有重要的經(jīng)濟(jì)效益和社會效益。鎂合金鑄件的補(bǔ)焊采用較多的是傳統(tǒng)鎢極惰性氣體保護(hù)焊(TIG),但是因其低生產(chǎn)效率、低成品率,不能滿足工程上鑄件補(bǔ)焊要求。為了提高TIG焊焊縫熔深并且改善焊縫質(zhì)量,人們提出活性化鎢極氬弧焊(Activating Flux TIG,A-TIG)焊接方法,A-TIG焊焊接方法是焊前在母材表面涂敷一層活性劑,在相同焊接規(guī)范下,A-TIG焊具有增加焊縫熔深、大幅度地消減焊縫氣孔等優(yōu)勢。因此,本文將A-TIG焊焊接方法應(yīng)用于鑄造鎂合金補(bǔ)焊,提出一種新型A-TIG補(bǔ)焊方法,研究其與TIG補(bǔ)焊工藝的區(qū)別,以便提高補(bǔ)焊效率和成品率。模擬補(bǔ)焊鑄造鎂合金孔洞類缺陷試驗,同焊接參數(shù)條件下(I=120A, V=5mm/s),TIG補(bǔ)焊鑄造鎂合金只可以愈合lmm深的孔洞,而A-TIG可以愈合3mm深的孔洞；同愈合程度條件下(孔深h=3mm、孔徑口=3mm) TIG補(bǔ)焊鑄造鎂合金在焊接電流200A時可以獲得同A-TIG補(bǔ)焊在焊接電流120A時相同的愈合效果,但是前者焊縫中出現(xiàn)明顯的氣孔缺陷；對變形鎂合金進(jìn)行模擬試驗發(fā)現(xiàn),A-TIG補(bǔ)焊能力優(yōu)于TIG補(bǔ)焊能力,但補(bǔ)焊后的焊縫表面和縱截面沒有發(fā)現(xiàn)焊接氣孔缺陷,這說明變形鎂合金和鑄造鎂合金母材的差異導(dǎo)致焊接氣孔的產(chǎn)生；補(bǔ)焊后焊接接頭的微觀組織和顯微硬度觀察發(fā)現(xiàn),利用A-TIG進(jìn)行補(bǔ)焊不但可以實現(xiàn)較深孔洞的愈合,而且可以減少焊縫氣孔缺陷,具有提高效率和減少缺陷的效果；為進(jìn)一步減少補(bǔ)焊缺陷以及探究A-TIG補(bǔ)焊減少氣孔缺陷的機(jī)理,進(jìn)行A-TIG焊自動冷填絲工藝研究,采用后向送絲工藝進(jìn)行鑄造鎂合金模擬孔洞類缺陷補(bǔ)焊試驗,并且焊后沒有發(fā)現(xiàn)氣孔缺陷；A-TIG補(bǔ)焊能減少氣孔缺陷主要Zr02活性劑能向焊縫中引入鋯元素,提高焊縫固氫能力,A-TIG焊熔池內(nèi)部流動性具有一致性,熔池側(cè)壁自下向上運動,這種流動方式有助于氣泡的排除；提出鑄造鎂合金補(bǔ)焊規(guī)范工藝及進(jìn)行鑄件補(bǔ)焊示范應(yīng)用。
[Abstract]:Magnesium alloy is widely used in aerospace, automobile, electronic communication and other fields because of its excellent characteristics. The lightweight goal can be achieved effectively through the use of magnesium alloy parts. Because of the high production cost of wrought magnesium alloys, the main magnesium alloys used in industry at present are castings. Various kinds of defects, such as pores, cracks and so on, are easy to appear in the casting process of magnesium alloys. Or the defects in the process of machining and transportation cause the casting to become unqualified, which not only causes a great waste of materials but also affects the delivery and use of the products. Therefore, it has important economic and social benefits to repair the defects of castings. The traditional tungsten inert gas shielded arc welding (TIG),) is widely used in magnesium alloy castings, but because of its low production efficiency and low yield, it can not meet the requirements of engineering casting repair welding. In order to improve the penetration of TIG welding seam and improve the weld quality, the activated tungsten argon arc welding (Activating Flux TIG,A-TIG) welding method is proposed. The A-TIG welding method is to coat a layer of flux on the base metal surface before welding. Under the same welding criterion, A-TIG welding has the advantages of increasing weld penetration and reducing weld hole greatly. Therefore, in this paper, the A-TIG welding method is applied to the casting magnesium alloy repair welding, a new A-TIG repair welding method is proposed, and the difference between the A-TIG repair welding method and the TIG repair welding process is studied in order to improve the repair welding efficiency and the finished product rate. Under the condition of welding parameters (I, 120A, V=5mm/s), TIG), the casting magnesium alloy can only heal the deep holes of lmm, while A-TIG can heal the deep holes of 3mm under the condition of welding parameters (I) 120A, and the A-TIG can heal the deep holes of 3mm under the condition of the same welding parameters as the welding parameters. Under the condition of the same healing degree (3 mm hole depth, diameter = 3mm), the same healing effect can be obtained when the welding current is 200A in the casting magnesium alloy cast magnesium alloy as that in the A-TIG repair welding at the welding current of 120A, but there are obvious hole defects in the former weld. The simulation results of magnesium alloy show that A-TIG repair welding ability is superior to TIG repair welding ability, but the weld surface and longitudinal section after repair welding do not find the weld hole defect, but the welding hole defect is not found in the weld surface and longitudinal section after repair welding. This indicates that the difference between wrought magnesium alloy and cast magnesium alloy base metal results in the formation of welding pores. The microstructure and microhardness of welded joints after repair welding are observed. It is found that A-TIG can not only heal the deep holes, but also reduce the hole defects in the weld, and improve the efficiency and reduce the defects. In order to further reduce the defect of repair welding and explore the mechanism of reducing hole defect in A-TIG repair welding, the automatic cold wire filling technology of A-TIG welding was studied, and the casting magnesium alloy simulated hole defect repair welding test was carried out by the backward wire feeding process. No pore defects were found after welding. A-TIG repair welding can reduce the pore defects. The main Zr02 flux can introduce zirconium into the weld and improve the hydrogen fixation ability of the weld. The internal fluidity of the weld pool in A-TIG welding is consistent, and the side wall of the weld pool moves from bottom to bottom. This flow mode is helpful for the removal of bubbles. The specification and application of casting magnesium alloy repair welding are put forward.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TG457.1
本文編號：2439678
[Abstract]:Magnesium alloy is widely used in aerospace, automobile, electronic communication and other fields because of its excellent characteristics. The lightweight goal can be achieved effectively through the use of magnesium alloy parts. Because of the high production cost of wrought magnesium alloys, the main magnesium alloys used in industry at present are castings. Various kinds of defects, such as pores, cracks and so on, are easy to appear in the casting process of magnesium alloys. Or the defects in the process of machining and transportation cause the casting to become unqualified, which not only causes a great waste of materials but also affects the delivery and use of the products. Therefore, it has important economic and social benefits to repair the defects of castings. The traditional tungsten inert gas shielded arc welding (TIG),) is widely used in magnesium alloy castings, but because of its low production efficiency and low yield, it can not meet the requirements of engineering casting repair welding. In order to improve the penetration of TIG welding seam and improve the weld quality, the activated tungsten argon arc welding (Activating Flux TIG,A-TIG) welding method is proposed. The A-TIG welding method is to coat a layer of flux on the base metal surface before welding. Under the same welding criterion, A-TIG welding has the advantages of increasing weld penetration and reducing weld hole greatly. Therefore, in this paper, the A-TIG welding method is applied to the casting magnesium alloy repair welding, a new A-TIG repair welding method is proposed, and the difference between the A-TIG repair welding method and the TIG repair welding process is studied in order to improve the repair welding efficiency and the finished product rate. Under the condition of welding parameters (I, 120A, V=5mm/s), TIG), the casting magnesium alloy can only heal the deep holes of lmm, while A-TIG can heal the deep holes of 3mm under the condition of welding parameters (I) 120A, and the A-TIG can heal the deep holes of 3mm under the condition of the same welding parameters as the welding parameters. Under the condition of the same healing degree (3 mm hole depth, diameter = 3mm), the same healing effect can be obtained when the welding current is 200A in the casting magnesium alloy cast magnesium alloy as that in the A-TIG repair welding at the welding current of 120A, but there are obvious hole defects in the former weld. The simulation results of magnesium alloy show that A-TIG repair welding ability is superior to TIG repair welding ability, but the weld surface and longitudinal section after repair welding do not find the weld hole defect, but the welding hole defect is not found in the weld surface and longitudinal section after repair welding. This indicates that the difference between wrought magnesium alloy and cast magnesium alloy base metal results in the formation of welding pores. The microstructure and microhardness of welded joints after repair welding are observed. It is found that A-TIG can not only heal the deep holes, but also reduce the hole defects in the weld, and improve the efficiency and reduce the defects. In order to further reduce the defect of repair welding and explore the mechanism of reducing hole defect in A-TIG repair welding, the automatic cold wire filling technology of A-TIG welding was studied, and the casting magnesium alloy simulated hole defect repair welding test was carried out by the backward wire feeding process. No pore defects were found after welding. A-TIG repair welding can reduce the pore defects. The main Zr02 flux can introduce zirconium into the weld and improve the hydrogen fixation ability of the weld. The internal fluidity of the weld pool in A-TIG welding is consistent, and the side wall of the weld pool moves from bottom to bottom. This flow mode is helpful for the removal of bubbles. The specification and application of casting magnesium alloy repair welding are put forward.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TG457.1
【參考文獻(xiàn)】
相關(guān)期刊論文 前5條
1 張同俊,李星國;鎂合金的應(yīng)用和中國鎂工業(yè)[J];材料導(dǎo)報;2002年07期
2 游國強(qiáng);杜娟;譚霞;王向杰;;壓鑄鎂合金焊接氣孔問題研究現(xiàn)狀及發(fā)展[J];功能材料;2013年04期
3 張瑞華,樊丁;低碳鋼A-TIG焊活性劑的焊接性[J];焊接學(xué)報;2003年01期
4 張少卿;MB15鎂合金的相組成及其微觀形態(tài)[J];金屬學(xué)報;1989年05期
5 劉靜安;盛春磊;;鎂及鎂合金的應(yīng)用及市場發(fā)展前景[J];有色金屬加工;2007年02期
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