本文選題：超硬鋁合金 + 焊絲�。� 參考：《沈陽(yáng)工業(yè)大學(xué)》2017年碩士論文

【摘要】：鋁及其合金已經(jīng)廣泛地應(yīng)用于工業(yè)領(lǐng)域,產(chǎn)量?jī)H次于鋼鐵的第二大類金屬材料。目前,7075鋁合金由于具有比強(qiáng)度高、加工性能優(yōu)良等特點(diǎn),在航空航天發(fā)展中占有十分重要的地位。但是,7075超硬鋁合金其焊接性較差,焊接接頭常出現(xiàn)熱裂紋、氣孔和接頭軟化等焊接性缺陷,影響其廣泛應(yīng)用。因此,通過使用不同焊接材料,調(diào)整焊接工藝參數(shù)與工藝措施,研究分析其對(duì)7075超硬鋁合金焊接性及接頭組織影響規(guī)律。本課題對(duì)7075超硬鋁合金采用ER4043和ER5356兩種焊絲在不同焊接工藝條件下獲得的焊接接頭進(jìn)行性能檢測(cè)和組織分析,從而確定適合7075超硬鋁合金焊接性的焊接材料和工藝參數(shù)。外加縱向交流磁場(chǎng)進(jìn)行正交試驗(yàn),研究磁場(chǎng)參數(shù)和焊接工藝對(duì)焊接性及接頭組織性能的影響,實(shí)驗(yàn)結(jié)果表明:(1)采用ER5356焊絲焊接接頭(簡(jiǎn)稱ER5356焊接接頭)力學(xué)性能及組織比采用ER4043焊絲焊接接頭(簡(jiǎn)稱ER4043焊接接頭)好。隨著焊接電流的增加,焊接接頭的力學(xué)性能呈先增大后降低的變化趨勢(shì)。當(dāng)焊接電流增加至120A時(shí),ER4043焊接接頭力學(xué)性能達(dá)到最大:σb=287.4MPa、δ=3.85%,焊縫硬度為96.7HV,焊縫中Si產(chǎn)生低熔點(diǎn)共晶可降低裂紋敏感性;當(dāng)焊接電流增加至130A時(shí),ER5356焊接接頭力學(xué)性能達(dá)到最大:σb=310.0MPa、δ=4.44%,焊縫硬度為106.3HV,Mg元素形成強(qiáng)化相,提高組織性能,改善7075超硬鋁合金焊接性。(2)采用ER5356焊絲進(jìn)行正交試驗(yàn)確定最佳焊接工藝及磁場(chǎng)參數(shù)。當(dāng)焊接電流為130A,磁場(chǎng)電流為3.0A,磁場(chǎng)頻率為40Hz時(shí),焊接接頭的力學(xué)性能最大:σb=342.5MPa、δ=5.63%,焊縫硬度為112.2HV。與相同焊接工藝下未施加磁場(chǎng)的焊接接頭性能相比,組織得到改善,7075超硬鋁合金焊接接頭性能提高。(3)外加縱向交流磁場(chǎng)使電弧中的帶點(diǎn)粒子產(chǎn)生運(yùn)動(dòng),一方面帶電粒子運(yùn)動(dòng)使電弧發(fā)生旋轉(zhuǎn),產(chǎn)生電磁攪拌作用,焊縫晶粒細(xì)化;另一方面帶電粒子運(yùn)動(dòng)改變焊接電弧形貌,平衡熔池溫度,減少偏析,從而改善7075超硬鋁合金焊接性及焊接接頭組織性能。
[Abstract]:Aluminum and its alloys have been widely used in industrial fields, the second largest category of metal materials after iron and steel. At present, due to its high specific strength and excellent processing properties, the alloy plays an important role in the development of aeronautics and astronautics. However, the weldability of super hard aluminum alloy is poor, such as hot cracks, porosity and softening of joints, which affect its wide application. Therefore, by using different welding materials and adjusting welding process parameters and technological measures, the influence of welding parameters and process measures on the weldability and joint microstructure of 7075 superhard aluminum alloy is studied and analyzed. In this paper, the mechanical properties and microstructure of 7075 superhard aluminum alloy welded joints obtained by ER4043 and ER5356 wires under different welding process conditions were tested and analyzed, and the welding materials and process parameters suitable for the weldability of 7075 superhard aluminum alloy were determined. The effects of magnetic field parameters and welding process on the weldability and microstructure and properties of the joints were studied by orthogonal experiments with external longitudinal alternating magnetic field. The experimental results show that the mechanical properties and microstructure of ER5356 wire welded joint are better than that of ER4043 wire welded joint (ER4043 welding joint). With the increase of welding current, the mechanical properties of welded joints increase first and then decrease. When the welding current is increased to 120A, the mechanical properties of the welded joints reach the maximum: 蟽 _ (b) 287.4MPa, 未 ~ (3.85), the hardness of the weld is 96.7HV.The low melting point eutectic produced in the weld can reduce the crack sensitivity. When the welding current is increased to 130A, the mechanical properties of the welded joints reach the maximum: 蟽 _ (b) 310.0 MPa, 未 _ (4.44), the hardness of weld is 106.3 HVN mg, and the microstructure and properties of the welded joints are improved. To improve the weldability of 7075 superhard aluminum alloy, the best welding process and magnetic field parameters were determined by orthogonal test with ER5356 wire. When the welding current is 130 A, the magnetic field current is 3.0 A, and the magnetic field frequency is 40 Hz, the mechanical properties of the welded joint are maximum: 蟽 _ (b) 342.5 MPA, 未 ~ (5.63) and the hardness of weld is 112.2 HV. Compared with the welded joints without magnetic field applied in the same welding process, the microstructure improves the properties of the welded joints of the superhard aluminum alloy, I. e., the effect of longitudinal alternating magnetic field on the movement of the strip-point particles in the arc. On the one hand, the motion of charged particles causes the arc to rotate and produce electromagnetic stirring, and the grain of weld is refined. On the other hand, the motion of charged particles changes the shape of welding arc, balances the temperature of molten pool, and reduces segregation. So as to improve the weldability of 7075 super hard aluminum alloy and the microstructure and properties of welded joint.
【學(xué)位授予單位】：沈陽(yáng)工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG457.14

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