摘 要

隨著鎂合金應(yīng)用的日益廣泛，其焊接接頭的力學(xué)性能也越來(lái)越受到到人們的重視。目前，國(guó)內(nèi)外對(duì)鎂合金焊接技術(shù)的研究已經(jīng)取得了較大的進(jìn)展，各種先進(jìn)的焊接技術(shù)日益完善，為鎂合金焊接技術(shù)的發(fā)展提供了廣闊的前景。
本文主要針對(duì)壓鑄AZ91鎂合金的鎢極氬弧焊工藝進(jìn)行探索性研究，重點(diǎn)對(duì)焊接接頭組織和硬度進(jìn)行了分析。實(shí)驗(yàn)結(jié)果表明接頭組織中存在大量氣孔和組織疏松，而且氣孔有在熱影響區(qū)集中的趨勢(shì)，熱影響區(qū)的硬度明顯低于母材和焊縫區(qū)。鎢極氬弧焊焊接接頭產(chǎn)生的焊縫區(qū)晶粒較為粗大，焊接熱影響區(qū)較寬，氣孔、疏松等焊接缺陷較為明顯。因此，壓鑄態(tài)AZ91鎂合金焊接性較差。
另外，針對(duì)鎂合金鎢極氬弧焊容易出現(xiàn)的一些問(wèn)題提出了一些改進(jìn)方法，對(duì)今后鎂合金焊接的研究方向和發(fā)展作了展望。


關(guān)鍵詞：鎂合金，焊接接頭，鎢極氬弧焊，熱影響區(qū)



















ABSTRACT

As the increasing use of magnesium alloy in industry, the property of its welding joint is attracting more and more attention. Nowadays, the scientists from home and abroad have achieved a large fruit on the investigation of welding technique for magnesium alloy. All types of modern welding techniques are rapidly developed, and they show us a bright future for the welding of magnesium alloy.
The author focused on exploratory researching to the craft of Gas tungsten-arc welding the die-casting magnesium alloy AZ91, analyzing the organization of welding joint and degree of hardness was a focal point. The experimental result showed that the organization of welding joint had large quantity gas hole and structural rarefaction, and found the gas hole had a tendency to focus in the heat affected zone. The strength of the heat affected zone was visible lower than the base metal and weld zone. The welding joint welded by TIG had the coarse crystal grain, extensive the heat affected zone’s dimension, the gas hole and structural rarefaction, etc. Therefore, the weld-ability of the die-casting magnesium alloy AZ91 was bad.
Further more, the author pointed out some improving methods to the popular problems during the process of TIG, and also delivered some prospects on the welding of magnesium alloy.


Key words： magnesium alloy, welding joint, Gas tungsten-arc welding, the heat affected zone











目 錄

中文摘要 Ⅰ
ABSTRACT Ⅱ
1 緒論 1
1.1鎂合金簡(jiǎn)介 1
1.1.1 鎂的基本性質(zhì) 1
1.1.2 鎂資源簡(jiǎn)介 2
1.1.3 鎂合金特點(diǎn) 2
1.1.4 鎂合金分類(lèi)及表示方法 3
1.1.5 鎂合金的應(yīng)用 5
1.1.6 鎂合金在我國(guó)的使用現(xiàn)狀 6
1.2 鎂合金焊接方法簡(jiǎn)介 8
1.2.1 鎂合金的焊接和主要焊接方法 8
1.2.2 鎢極氬弧焊（TIG）及其特點(diǎn) 9
1.2.3 本課題的提出及意義 10
2 實(shí)驗(yàn)原理 11
2.1 鎢極氬弧焊的原理 11
2.2 光學(xué)顯微鏡的原理 12
2.3 金相顯微鏡的原理 12
2.4 洛氏硬度實(shí)驗(yàn)的原理 14
3 實(shí)驗(yàn)過(guò)程 15
3.1實(shí)驗(yàn)設(shè)備及材料 15
3.2 實(shí)驗(yàn)準(zhǔn)備 16
3.3 實(shí)驗(yàn)過(guò)程 17
3.3.1 鎢極氬弧焊（TIG）焊接鎂合金板 17
3.3.2 金相實(shí)驗(yàn) 18
3.3.2 硬度實(shí)驗(yàn) 19
4 實(shí)驗(yàn)結(jié)果及分析 20
4.1實(shí)驗(yàn)結(jié)果 20
4.1.1 焊接實(shí)驗(yàn)結(jié)果 20
4.1.2 金相實(shí)驗(yàn)結(jié)果 23
4.1.3 硬度實(shí)驗(yàn)結(jié)果 25
4.2結(jié)果分析 26
4.2.1 焊接及試樣表面分析 26
4.2.2 焊接試樣的組織分析 27
4.3.3 焊接試樣的性能分析 28
5 結(jié)論及展望 29

參考文獻(xiàn) 30
致 謝 31