本文選題：雙軸肩攪拌摩擦焊 + AZ61鎂合金��； 參考：《哈爾濱工業(yè)大學(xué)》2017年碩士論文

【摘要】：雙軸肩攪拌摩擦焊技術(shù)是在常規(guī)攪拌摩擦焊技術(shù)的基礎(chǔ)上發(fā)展起而來,其在保留了固相連接技術(shù)優(yōu)點的基礎(chǔ)上,又簡化了焊接工裝、克服了焊縫根部未焊合缺陷等問題。本文針對5mm厚AZ61鎂合金開展工藝與機理研究,設(shè)計了雙軸肩攪拌頭,實施了焊接工藝試驗,得到了合適的焊接工藝參數(shù)區(qū)間,揭示了工藝參數(shù)與接頭成形、焊接過程參數(shù)、接頭微觀組織及力學(xué)性能的聯(lián)系,從而闡明接頭形成機理,為工程應(yīng)用奠定理論基礎(chǔ)。焊接工藝試驗結(jié)果表明AZ61鎂合金雙軸肩攪拌摩擦焊焊接工藝參數(shù)區(qū)間較窄,通過合理的焊具設(shè)計在一定工藝范圍內(nèi)能夠獲得成形良好、無缺陷的接頭。為了建立過程參數(shù)與接頭成形的對應(yīng)關(guān)系,為工藝參數(shù)的優(yōu)化提供指導(dǎo),對焊接過程特征參數(shù)進行測量。發(fā)現(xiàn)隨著攪拌頭轉(zhuǎn)速的提高,熱輸入量增大導(dǎo)致測溫點監(jiān)測到的峰值溫度提高,主軸和X軸輸出扭矩均有所下降;而隨著焊接速度的提高,焊接線能量下降,材料軟化程度不足,測溫點峰值溫度降低,主軸和X軸輸出扭矩升高。當(dāng)溫度或扭矩過高或過低時,都無法形成連續(xù)的無缺陷焊縫。由于有兩個軸肩的存在,AZ61鎂合金雙軸肩攪拌摩擦焊焊縫區(qū)域呈啞鈴狀,對接頭進行微觀組織分析可以發(fā)現(xiàn)接頭可分為母材、熱影響區(qū)、熱機影響區(qū)和焊核區(qū)四個區(qū)域。焊核區(qū)內(nèi)均為細(xì)小的等軸晶,且沿厚度方向晶粒尺寸沒有明顯變化;接頭的熱機影響區(qū)也主要由等軸晶組成;熱影響區(qū)的組織較為粗大;焊核區(qū)、熱機影響區(qū)和熱影響區(qū)的平均晶粒尺寸和焊接工藝參數(shù)明顯相關(guān),均隨著攪拌頭轉(zhuǎn)速的升高而增大,隨著焊接速度的升高而減小。接頭力學(xué)性能分析結(jié)果表明,AZ61鎂合金雙軸肩攪拌摩擦焊接頭硬度整體接頭硬度分布均勻,各區(qū)域硬度值均在52-65HRC之間波動。工藝參數(shù)對接頭熱影響區(qū)和熱機影響區(qū)的顯微硬度無明顯影響。在熱輸入量較低的焊接工藝條件下,接頭焊核區(qū)的顯微硬度高于其他區(qū)域。拉伸試驗表明有缺陷接頭的拉伸性能很差,斷口表面呈現(xiàn)韌脆混合型斷裂,而無缺陷接頭的拉伸性能良好,其最大抗拉強度可達213MPa,相當(dāng)于母材的80%,呈韌性斷裂。沖擊試驗結(jié)果表明,工藝參數(shù)對接頭的沖擊性能有明顯影響,而焊核區(qū)的沖擊吸收功始終高于熱影響區(qū)和母材,熱影響區(qū)沖擊試樣呈現(xiàn)韌脆混合型斷裂而焊核區(qū)試樣呈現(xiàn)韌性斷裂。
[Abstract]:The technology of double shaft shoulder friction stir welding is developed on the basis of the conventional friction stir welding technology. On the basis of retaining the advantages of solid phase joining technology, it also simplifies the welding equipment and overcomes the problems such as the failure to weld at the root of the weld, and so on. In this paper, the technology and mechanism of 5mm thick AZ61 magnesium alloy are studied, the double shaft shoulder mixing head is designed, the welding process test is carried out, the appropriate welding process parameter interval is obtained, and the process parameters and joint forming and welding process parameters are revealed. The connection between the microstructure and mechanical properties of the joints can clarify the formation mechanism of the joints and lay a theoretical foundation for the engineering application. The results of welding test show that the range of welding parameters of AZ61 magnesium alloy with double shaft shoulder friction stir welding is narrow, and the joints with good shape and no defects can be obtained by reasonable design of welding tools. In order to establish the corresponding relationship between process parameters and joint forming and to provide guidance for optimization of process parameters, the characteristic parameters of welding process were measured. It is found that with the increase of the rotating speed of the mixing head, the increase of the heat input leads to the increase of the peak temperature detected at the temperature measuring point, and the decrease of the output torque of the spindle and the X axis, and the decrease of the welding line energy with the increase of the welding speed. The softening degree of the material is insufficient, the peak temperature of the temperature measuring point is decreased, and the output torque of the spindle and X axis is increased. When the temperature or torque is too high or too low, no continuous defect weld can be formed. Due to the existence of two shafts, the weld zone of friction stir welding of magnesium alloy AZ61 magnesium alloy with double shafts is dumbbell-like. By analyzing the microstructure of the joint, it can be found that the joint can be divided into four regions: base metal, heat affected zone, heat engine affected zone and nuke zone. The nugget zone is small equiaxed crystal, and the grain size does not change obviously along the thickness direction. The thermal machine-affected zone of the joint is also mainly composed of equiaxed crystal, the microstructure of the heat-affected zone is relatively large, the weld nugget zone, The average grain size of the heat affected zone and the heat affected zone are significantly correlated with the welding process parameters, both of which increase with the increase of the rotating speed of the stirring head and decrease with the increase of the welding speed. The mechanical properties of the joints show that the hardness distribution of the joint is uniform and the hardness values of the joints fluctuate between 52-65HRC. The process parameters have no obvious effect on the microhardness of the heat-affected zone and the heat-affected zone of the joint. Under the condition of low heat input, the microhardness of joint nugget zone is higher than that of other regions. The tensile tests show that the tensile properties of the defective joints are very poor, and the fracture surfaces exhibit ductile and brittle mixed fracture, while the non-defective joints have good tensile properties. The maximum tensile strength of the joints is up to 213MPa, which is equivalent to 80% of the base metal, showing ductile fracture. The impact test results show that the process parameters have a significant effect on the impact properties of the joints, and the impact absorption energy in the nugget zone is always higher than that in the heat-affected zone and the base metal. The impact specimens in the heat affected zone exhibit ductile and brittle mixed fracture, while the specimens in the nuke zone show ductile fracture.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG457.19

【參考文獻】

相關(guān)期刊論文 前10條

1 馬鋒;王德升;楊昊;孟祥軍;;ZK61鎂合金攪拌摩擦焊的焊縫組織及力學(xué)性能[J];熱加工工藝;2016年23期

2 趙妍;胡偉葉;周海峰;戴維弟;欒國紅;;厚板鎂合金攪拌摩擦焊性能與組織分析[J];航空制造技術(shù);2013年21期

3 董繼紅;董春林;孟強;欒國紅;焦向東;;鋁合金浮動式雙軸肩FSW接頭組織性能分析[J];焊接學(xué)報;2013年10期

4 李敬勇;周小平;董春林;董繼紅;;6082鋁合金雙軸肩攪拌摩擦焊試板溫度場研究[J];航空材料學(xué)報;2013年05期

5 郁炎;晏陽陽;高福洋;;國內(nèi)外攪拌摩擦焊用攪拌頭的研究現(xiàn)狀及發(fā)展趨勢[J];材料開發(fā)與應(yīng)用;2013年03期

6 周楠;戚文軍;王海艷;農(nóng)登;宋東福;;鎂合金攪拌摩擦焊技術(shù)的研究進展[J];材料導(dǎo)報;2011年S2期

7 張云燕;;鎂合金薄板的攪拌摩擦焊工藝[J];硅谷;2010年17期

8 于思榮;陳顯軍;劉耀輝;;AZ31B鎂合金攪拌摩擦焊焊接工藝研究[J];新技術(shù)新工藝;2009年11期

9 欒國紅;;飛機制造中的攪拌摩擦焊技術(shù)及其發(fā)展[J];航空制造技術(shù);2009年20期

10 ;雙軸肩攪拌摩擦焊技術(shù)取得突破[J];現(xiàn)代焊接;2009年10期

相關(guān)碩士學(xué)位論文 前2條

1 張均成;壓鑄態(tài)AZ91D鎂合金攪拌摩擦焊組織與力學(xué)性能研究[D];重慶大學(xué);2013年

2 肖詩雨;鎂合金攪拌摩擦焊溫度場及接頭組織性能研究[D];江蘇科技大學(xué);2013年

，

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