發(fā)布時(shí)間：2018-01-01 14:01

  本文關(guān)鍵詞：鋁合金磁控MIG焊接電弧特性及焊縫組織性能的研究　出處：《沈陽(yáng)工業(yè)大學(xué)》2017年碩士論文　論文類(lèi)型：學(xué)位論文

  更多相關(guān)文章： 鋁合金 交變縱向磁場(chǎng) 焊接電弧 焊縫成形 氣孔率

【摘要】：Al-Mg系鋁合金在現(xiàn)代制造業(yè)追求輕量化發(fā)展過(guò)程中應(yīng)用越來(lái)越廣泛,但鋁合金MIG焊接時(shí)存在焊縫成形性差、結(jié)晶組織粗大、焊縫氣孔率高等問(wèn)題,限制了Al-Mg系鋁合金大范圍使用。文章以5083鋁合金作為實(shí)驗(yàn)對(duì)象,通過(guò)施加交變縱向磁場(chǎng)方法來(lái)探究磁場(chǎng)參數(shù)中勵(lì)磁電流及勵(lì)磁頻率對(duì)焊接電弧、熔滴過(guò)渡及焊接熔池的影響。進(jìn)而通過(guò)高速攝像機(jī)、金相觀(guān)察、力學(xué)性能測(cè)試、X射線(xiàn)無(wú)損探傷等方法來(lái)分析磁場(chǎng)參數(shù)對(duì)焊接電弧、熔滴過(guò)渡、結(jié)晶組織、力學(xué)性能、氣孔率的影響規(guī)律,并探究作用機(jī)理。通過(guò)高速攝像與電信號(hào)動(dòng)態(tài)分析系統(tǒng)觀(guān)察電弧運(yùn)動(dòng)及熔滴過(guò)渡過(guò)程,并建立電弧空間內(nèi)粒子受力模型來(lái)分析焊接電弧運(yùn)動(dòng)機(jī)理。實(shí)驗(yàn)得出:無(wú)磁場(chǎng)下,電弧形態(tài)形似錐形。當(dāng)施加交變縱向磁場(chǎng)時(shí),隨勵(lì)磁電流及勵(lì)磁頻率增大,電弧產(chǎn)生旋轉(zhuǎn),且電弧旋轉(zhuǎn)程度隨勵(lì)磁電流變大而加強(qiáng),表現(xiàn)為先擴(kuò)散后縮緊形態(tài)。尤其當(dāng)勵(lì)磁電流2A、勵(lì)磁頻率45Hz時(shí),焊接電弧表現(xiàn)為以焊絲為軸線(xiàn)的中心對(duì)稱(chēng)分布,由無(wú)磁場(chǎng)時(shí)的錐形變?yōu)殓娬中�。隨磁場(chǎng)參數(shù)加大,熔滴由無(wú)磁場(chǎng)時(shí)的圓球狀逐步轉(zhuǎn)變成橢球狀,熔滴過(guò)渡頻率先增大后變小,在勵(lì)磁電流2A下達(dá)到最大,每滴約5.8ms。當(dāng)磁場(chǎng)參數(shù)在一定范圍內(nèi)增加,在宏觀(guān)形貌上,焊縫表面魚(yú)鱗紋變得更加致密,焊縫熔寬先增加后減小,焊縫熔深主要受勵(lì)磁電流影響先減小后增大,但在焊接電弧穩(wěn)定燃燒時(shí)受勵(lì)磁頻率影響較小。在微觀(guān)組織上,引入磁場(chǎng)促進(jìn)了結(jié)晶組織由柱狀晶轉(zhuǎn)變成等軸晶,焊縫晶粒變得細(xì)小。尤其當(dāng)勵(lì)磁電流2A、勵(lì)磁頻率45Hz時(shí),焊縫組織細(xì)小,此時(shí)與無(wú)外加磁場(chǎng)時(shí)相比焊接接頭抗拉強(qiáng)度提高了34.7MPa、伸長(zhǎng)率提高了5.86%、接頭最大硬度值提高11HV。隨外加磁場(chǎng)引入,一定長(zhǎng)度焊縫上氣孔數(shù)目明顯下降,說(shuō)明磁場(chǎng)參數(shù)對(duì)焊縫氣孔率有著顯著的影響。在勵(lì)磁電流2A、勵(lì)磁頻率45Hz時(shí),焊縫中氣孔數(shù)目由無(wú)磁場(chǎng)時(shí)8個(gè)變?yōu)?個(gè),有效降低了焊縫氣孔率。
[Abstract]:More and more widely used Aluminum Alloy seeking light with the development of modern manufacturing process in Al-Mg system, but Aluminum Alloy MIG welding weld are poor, coarse grains, high weld porosity, limiting the use of a wide range of Al-Mg Aluminum Alloy. Taking 5083 Aluminum Alloy as experimental object, by applying an alternating longitudinal the magnetic field method to explore the welding arc excitation current and excitation frequency of the magnetic field parameters, droplet transfer and influence of welding pool. Then through metallographic observations of high speed camera, mechanical properties test, to analyze the magnetic field parameters of arc welding nondestructive testing methods such as X ray, droplet transfer, microstructure, mechanical properties, impact law of porosity, and explore the mechanism. By observing the motion of arc and droplet transfer process and dynamic signal analysis system of high speed camera, and the establishment of the arc space particle force model To analyze welding arc motion mechanism. Experiment results: no magnetic field, the arc shape resembling a cone. When applying an alternating longitudinal magnetic field, with excitation current and excitation frequency increases, caused by the rotation, and rotation arc degree with excitation current becomes larger and the strengthening performance of the first diffusion after tightening form. Especially when the excitation current of 2A. The excitation frequency of 45Hz, the welding arc performance of the wire as the center symmetry axis, by cone without magnetic field into a bell shape. With the increase of magnetic field parameters, droplet by magnetic field in the spherical gradually transformed into ellipsoidal and the droplet transfer frequency increases first and then decreases, reaches the maximum at the excitation the current 2A, every drop of about 5.8ms. when the magnetic field parameters are increased to a certain extent, in the macro morphology on the weld surface ripple becomes more dense, the weld width increased first and then decreased, the weld penetration is mainly affected by the excitation current decreased Increased, but in the welding arc burns stably when the excitation frequency is less affected. The microstructure, magnetic field promotes the crystal structure changed from columnar grains to equiaxed grain. The weld grain becomes small. Especially when the excitation current is 2A, the excitation frequency is 45Hz, the weld microstructure is small, when compared with no external magnetic field the tensile strength of welded joints increased 34.7MPa, elongation increased by 5.86%, the joint maximum hardness value increased 11HV. with the applied magnetic field, a certain length of weld stomata decreased significantly, indicating the magnetic field parameters have significant effects on weld porosity. In the excitation current of 2A, the excitation frequency of 45Hz, the number of stomata in the weld by magnetic field 8 to 2, effectively reducing the weld porosity.

【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(lèi)號(hào)】：TG457.14

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