本文選題：橫向偏轉(zhuǎn)磁場 + 橫向旋轉(zhuǎn)磁場��； 參考：《上海工程技術(shù)大學》2016年碩士論文

【摘要】：對焊接過程施加磁場,一方面可以改變焊接電弧的形態(tài),進而改變焊接電弧的作用區(qū)域以及能量的分布,另一方面還可以對熔池金屬進行攪拌,抑制枝狀晶的形成,最終起到細化晶粒的目的,改善焊縫的質(zhì)量。本文主要研究了在橫向偏轉(zhuǎn)磁場和橫向旋轉(zhuǎn)磁場作用下電弧的運動形態(tài),重點研究在橫向偏轉(zhuǎn)磁場和橫向旋轉(zhuǎn)磁場作用下,不同的磁場大小對于電弧的偏轉(zhuǎn)幅度和電弧形態(tài)。研究表明,施加直流橫向偏轉(zhuǎn)磁場時,電弧偏轉(zhuǎn)幅度會隨著磁場強度的增大而增大,電弧在母材作用范圍在偏轉(zhuǎn)一側(cè)被拉長,形狀呈近半圓加橢圓,并且電弧的穩(wěn)定性也逐漸變差。施加交流橫向偏轉(zhuǎn)磁場時,在一定磁場范圍內(nèi),電弧發(fā)生擺動的最大偏轉(zhuǎn)幅度會隨著磁場強度增大而增大,電弧在母材上作用范圍在偏轉(zhuǎn)方向兩側(cè)拉長,形狀呈被拉長的橢圓。當磁場頻率600≤υ≤900時,電弧會以焊接方向軸線為中心,左右擺動;當磁場的頻率900≤υ≤1500時,電弧會受到一個“磁約束力”的作用,宏觀觀察電弧的偏轉(zhuǎn)和旋轉(zhuǎn)并不明顯,此時的的焊接電弧會相對穩(wěn)定;當磁場頻率1500≤υ時,此時帶電粒子受洛倫茲力增大,此時電弧不太穩(wěn)定,并且電弧的亮度下降,并有熄弧的傾向。施加橫向旋轉(zhuǎn)磁場時,電弧發(fā)生旋轉(zhuǎn),磁場強度較小時,電弧在母材上作用區(qū)域呈兩個同心圓,內(nèi)部小圓部分熱量較大;當磁場強度到某一特定值時,電弧作用范圍形狀為近似圓形,面積較未施加磁場時變大,能量較小;磁場強度進一步增大,母材受熱區(qū)域為圓環(huán)狀,此時不能形成焊縫。當改變磁場的頻率后,電弧穩(wěn)定性的變化與橫向交流磁場中電弧隨著磁場頻率變化類似。文章進行了工藝試驗,并對所取得的焊接接頭進行了機械性能研究和微觀組織的觀察。試驗表明旋轉(zhuǎn)磁場的施加會改善焊縫成形,使得熔池變淺變寬,改善焊縫中部突出的現(xiàn)象,一定程度上降低焊縫的應(yīng)力集中。橫向旋轉(zhuǎn)磁場的施加會細化焊縫金屬和HAZ金屬的晶粒,減少板條馬氏體和塊狀鐵素體的含量和晶粒尺寸,同時也會細化針狀鐵素體,使得焊接接頭的性能提高。施加焊接磁場后的焊接接頭在硬度方面會有一個明顯的提高,同時缺陷也會減少。
[Abstract]:On the one hand, applying magnetic field to welding process can change the shape of welding arc, and then change the area of action and the distribution of energy of welding arc, on the other hand, it can stir the molten pool metal and inhibit the formation of dendrite. Finally, the aim of grain refinement is to improve the quality of weld seam. In this paper, the motion of arc under the action of transverse deflection magnetic field and transverse rotating magnetic field is mainly studied, and the effect of different magnetic field on the arc deflection amplitude and arc shape is mainly studied under the action of transverse deflection magnetic field and transverse rotating magnetic field. The results show that when the DC transverse deflection magnetic field is applied, the arc deflection amplitude will increase with the increase of the magnetic field intensity, the arc will be elongated on the deflection side of the base metal, and the shape of the arc will be nearly semicircle and ellipse. And the stability of the arc is becoming worse. When the AC transverse deflection magnetic field is applied, in a certain magnetic field range, the maximum deflection amplitude of the arc swinging will increase with the increase of the magnetic field intensity, and the arc action range on the base metal will be elongated on both sides of the deflection direction with the shape of the elongated ellipse. When the frequency of magnetic field is 600 鈮，

本文編號：1927906