鑄造am60鎂合金tig焊接頭組織性能研究（本科畢業(yè)論文設(shè)計(jì)）.doc
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鑄造am60鎂合金tig焊接頭組織性能研究（本科畢業(yè)論文設(shè)計(jì)）,摘要鎂合金作為現(xiàn)有的最輕的商用金屬結(jié)構(gòu)材料，具有比重輕、高比強(qiáng)度、高比剛度，減振吸噪能力強(qiáng)，以及良好的電磁屏蔽能力和鑄造性能和易于再生利用等一系列獨(dú)特的優(yōu)點(diǎn)，被譽(yù)為“21世紀(jì)的綠色結(jié)構(gòu)材料”，在國防軍工、航空航天、交通工具、3c產(chǎn)品及手動(dòng)工具等領(lǐng)域有著極為廣闊的應(yīng)用前景。本文對(duì)3.0mm厚的am60鎂合金薄板（壓鑄態(tài)）...
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摘 要
鎂合金作為現(xiàn)有的最輕的商用金屬結(jié)構(gòu)材料，具有比重輕、高比強(qiáng)度、高比剛度，減振吸噪能力強(qiáng)，以及良好的電磁屏蔽能力和鑄造性能和易于再生利用等一系列獨(dú)特的優(yōu)點(diǎn)，被譽(yù)為“21世紀(jì)的綠色結(jié)構(gòu)材料”，在國防軍工、航空航天、交通工具、3C產(chǎn)品及手動(dòng)工具等領(lǐng)域有著極為廣闊的應(yīng)用前景。
本文對(duì)3.0mm厚的AM60鎂合金薄板（壓鑄態(tài)）的鎢極氬弧焊工藝進(jìn)行了試驗(yàn)，采用金相顯微鏡分析測(cè)試手段研究了焊接接頭各區(qū)域的顯微組織，并進(jìn)行了硬度測(cè)試等。
試驗(yàn)結(jié)果表明：采用TIG焊焊接壓鑄AM60合金時(shí)，焊縫成形不佳。微觀組織分析表明：AM60 鎂合金TIG 焊時(shí)，焊縫區(qū)為細(xì)小的等軸晶組織，晶界和晶粒內(nèi)部存在析出相, 熱影響區(qū)晶粒較粗大，且熱影響區(qū)較寬。焊接接頭的主要缺陷是氣孔，氣孔產(chǎn)生的主要原因是：壓鑄態(tài)的母材中存在微孔等缺陷；焊接過程中由于氫在鎂中的溶解度急劇下降和焊縫凝固很快不利于氣體溢出導(dǎo)致較多氫氣孔出現(xiàn)；鎂合金中低熔點(diǎn)高蒸汽壓鎂元素的蒸發(fā)也是氣孔的來源之一。硬度測(cè)試表明：焊縫硬度相對(duì)較高，而熱影響區(qū)硬度明顯下降，是由于焊縫的晶粒細(xì)小，熱影響區(qū)晶粒粗大、且存在疏松等缺陷。
關(guān)鍵詞：AM60鎂合金，鎢極氬弧焊，組織，性能，氣孔
ABSTRACT
Magnesium alloys, as the lightest structural material at present , have many advantages, such as high specific strength, high specific rigidity, good casting capability and easy to recycle. As a result, magnesium alloys are named with “Green structural material of the 21th century”, and have a huge potential in mass application in road vehicles, aircrafts, space shuttles, communication and electronic goods.
In this thesis, the processing of gas tungsten arc (TIG) welding of magnesium alloy AM60 plates with 3.0 thickness were studied. The microstructure was investigated with optical microscopy.
The result indicated that the quality of the welding is not good. It’s found that the large number of pores in the joint seriously impact the mechanical property of the joint，the pores may be reduced by adjusting the parameters and eliminating the factors of gas，but they can’t be entirety avoided. Magnesium has higher hydrogen solubility in liquid than in solid. The difference in the solubility between the solid and liquid phase was major cause of the porosity of magnesium alloys during welding. The low melting element of magnesium alloy was easily to vaporize and the presence of porosity in the base metal coalesced and expanded，which was another cause. The hardness test indicate that the structure in weld is harder than other areas.
Key word: magnesium alloy AM60，TIG，microstructure，property，porosity
目 錄
中文摘要 Ⅰ
ABSTRACT Ⅱ
1緒論 1
1.1 引言 1
1.2鎂合金在我國的應(yīng)用現(xiàn)狀 1
1.3鎂合金的焊接特性及研究現(xiàn)狀 3
1.3.1 鎂合金的焊接特性 3
1.3.2 鎂合金焊接的研究現(xiàn)狀 4
1.4 本論文的研究內(nèi)容和意義 8
2 試驗(yàn) 9
2.1 試驗(yàn)設(shè)計(jì) 9
2.1.1 試驗(yàn)?zāi)康?9
2.1.2 試驗(yàn)原理 9
2.1.3 試驗(yàn)條件 13
2.2 試驗(yàn)過程 13
2.2.1 焊接試驗(yàn) 13
2.2.2 金相試樣制備及觀察 14
2.2.3 硬度測(cè)試 14
3 試驗(yàn)結(jié)果及分析 15
3.1 焊縫成形觀察 15
3.2 金相試驗(yàn)結(jié)果及分析 16
3.2.1 金相組織分析 16
3.2.2 缺陷分析 21
3.3 硬度試驗(yàn)結(jié)果及分析 24
4 結(jié)論 25
4.1 結(jié)論 25
4.2展望 25
致謝 26
參考文獻(xiàn) 27
鎂合金作為現(xiàn)有的最輕的商用金屬結(jié)構(gòu)材料，具有比重輕、高比強(qiáng)度、高比剛度，減振吸噪能力強(qiáng)，以及良好的電磁屏蔽能力和鑄造性能和易于再生利用等一系列獨(dú)特的優(yōu)點(diǎn)，被譽(yù)為“21世紀(jì)的綠色結(jié)構(gòu)材料”，在國防軍工、航空航天、交通工具、3C產(chǎn)品及手動(dòng)工具等領(lǐng)域有著極為廣闊的應(yīng)用前景。
本文對(duì)3.0mm厚的AM60鎂合金薄板（壓鑄態(tài)）的鎢極氬弧焊工藝進(jìn)行了試驗(yàn)，采用金相顯微鏡分析測(cè)試手段研究了焊接接頭各區(qū)域的顯微組織，并進(jìn)行了硬度測(cè)試等。
試驗(yàn)結(jié)果表明：采用TIG焊焊接壓鑄AM60合金時(shí)，焊縫成形不佳。微觀組織分析表明：AM60 鎂合金TIG 焊時(shí)，焊縫區(qū)為細(xì)小的等軸晶組織，晶界和晶粒內(nèi)部存在析出相, 熱影響區(qū)晶粒較粗大，且熱影響區(qū)較寬。焊接接頭的主要缺陷是氣孔，氣孔產(chǎn)生的主要原因是：壓鑄態(tài)的母材中存在微孔等缺陷；焊接過程中由于氫在鎂中的溶解度急劇下降和焊縫凝固很快不利于氣體溢出導(dǎo)致較多氫氣孔出現(xiàn)；鎂合金中低熔點(diǎn)高蒸汽壓鎂元素的蒸發(fā)也是氣孔的來源之一。硬度測(cè)試表明：焊縫硬度相對(duì)較高，而熱影響區(qū)硬度明顯下降，是由于焊縫的晶粒細(xì)小，熱影響區(qū)晶粒粗大、且存在疏松等缺陷。
關(guān)鍵詞：AM60鎂合金，鎢極氬弧焊，組織，性能，氣孔
ABSTRACT
Magnesium alloys, as the lightest structural material at present , have many advantages, such as high specific strength, high specific rigidity, good casting capability and easy to recycle. As a result, magnesium alloys are named with “Green structural material of the 21th century”, and have a huge potential in mass application in road vehicles, aircrafts, space shuttles, communication and electronic goods.
In this thesis, the processing of gas tungsten arc (TIG) welding of magnesium alloy AM60 plates with 3.0 thickness were studied. The microstructure was investigated with optical microscopy.
The result indicated that the quality of the welding is not good. It’s found that the large number of pores in the joint seriously impact the mechanical property of the joint，the pores may be reduced by adjusting the parameters and eliminating the factors of gas，but they can’t be entirety avoided. Magnesium has higher hydrogen solubility in liquid than in solid. The difference in the solubility between the solid and liquid phase was major cause of the porosity of magnesium alloys during welding. The low melting element of magnesium alloy was easily to vaporize and the presence of porosity in the base metal coalesced and expanded，which was another cause. The hardness test indicate that the structure in weld is harder than other areas.
Key word: magnesium alloy AM60，TIG，microstructure，property，porosity
目 錄
中文摘要 Ⅰ
ABSTRACT Ⅱ
1緒論 1
1.1 引言 1
1.2鎂合金在我國的應(yīng)用現(xiàn)狀 1
1.3鎂合金的焊接特性及研究現(xiàn)狀 3
1.3.1 鎂合金的焊接特性 3
1.3.2 鎂合金焊接的研究現(xiàn)狀 4
1.4 本論文的研究內(nèi)容和意義 8
2 試驗(yàn) 9
2.1 試驗(yàn)設(shè)計(jì) 9
2.1.1 試驗(yàn)?zāi)康?9
2.1.2 試驗(yàn)原理 9
2.1.3 試驗(yàn)條件 13
2.2 試驗(yàn)過程 13
2.2.1 焊接試驗(yàn) 13
2.2.2 金相試樣制備及觀察 14
2.2.3 硬度測(cè)試 14
3 試驗(yàn)結(jié)果及分析 15
3.1 焊縫成形觀察 15
3.2 金相試驗(yàn)結(jié)果及分析 16
3.2.1 金相組織分析 16
3.2.2 缺陷分析 21
3.3 硬度試驗(yàn)結(jié)果及分析 24
4 結(jié)論 25
4.1 結(jié)論 25
4.2展望 25
致謝 26
參考文獻(xiàn) 27
