鎂合金雙弧活性焊接微觀組織及性能分析
發(fā)布時間：2018-12-09 18:54
【摘要】：本文對2mm厚AZ31B鎂合金DE-GMAW(雙電極氣體保護焊)焊接進行研究,分析旁路電流、焊接電壓、焊接速度三個不同焊接參數(shù)對焊縫性能的影響,得出一個相對合適的焊接參數(shù)搭配。在這一焊接參數(shù)的基礎(chǔ)上,通過在母材表面涂覆一層活性劑SiC,研究SiC涂覆量對AZ31B鎂合金焊接性能的影響。實驗中通過分析焊縫的形貌和焊縫尺寸來研究各個參數(shù)對焊縫成型的影響,通過對接頭的金相組織、顯微硬度和抗拉強度等性能的分析,結(jié)果表明各個參數(shù)對接頭性能具有一定的影響。(1)在其他焊接參數(shù)一定的情況下,旁路電流從150A增加到180A過程中,焊縫熔寬和熔深都是在減小,而余高增加。通過測量得到焊縫熔合區(qū)中晶粒尺寸減小。焊接接頭顯微硬度在旁路電流逐漸增加的過程中呈現(xiàn)出逐漸增加的規(guī)律。通過對不同旁路電流所得的焊接接頭進行拉伸可知,接頭的抗拉強度從旁路電流為150A增加到180A過程中一直增加,當(dāng)旁路電流為180A時,抗拉強度急劇增加。(2)焊接電壓的增加使得焊縫熔寬增加,熔深和余高減小,在焊接電壓為23V時,焊縫成型最好。同時晶粒尺寸也增加,但增加量很小,可以認為基本不受影響。焊縫熔合區(qū)顯微硬度基本保持不變,接頭抗拉強度緩慢減小,而當(dāng)電壓為24V時焊縫未熔透,抗拉強度有所增加。(3)焊接速度從2.3m/min到2.9m/min焊接過程中,焊縫熔寬和熔深逐漸減小,而余高從焊接速度為2.3m/min開始增加到焊接速度為2.7m/min達到最大,焊縫熔合區(qū)晶粒尺寸變化規(guī)律同旁路電流時的變化規(guī)律相同。顯微硬度測試和拉伸實驗結(jié)果顯示,隨著焊接速度的增加,焊接頭顯微硬度和抗拉強度增加。(4)最終得出最優(yōu)焊接參數(shù)搭配為:主路電流I主=230A,旁路電流I旁=170A,焊接電壓U=23V,焊接速度V=2.7m/min。(5)焊縫熔深和余高隨SiC增加到ρ=5.64 mg/cm2的過程中逐漸增大,隨著SiC涂覆量進一步增加而減小,而熔寬的變化規(guī)律剛好相反。當(dāng)SiC添加量小于ρ=5.64 mg/cm2時,可以起到細化晶粒的作用,同時SiC顆粒可以使β-Mg17Al12在焊縫中彌散分布。SiC顆粒的添加有效的提高了焊接接頭的顯微硬度,并且隨著SiC涂覆量的增加接頭的顯微硬度逐漸增加。隨著SiC涂覆量的增加,接頭的抗拉強度增加。但當(dāng)SiC涂覆量大于ρ=5.64 mg/cm2時,焊接接頭抗拉強度明顯降低。
[Abstract]:In this paper, the welding of 2mm thick AZ31B magnesium alloy DE-GMAW (double electrode gas shielded welding) is studied. The influence of three welding parameters such as bypass current, welding voltage and welding speed on the weld performance is analyzed. A relatively suitable welding parameter is obtained. On the basis of these welding parameters, the effect of SiC coating amount on the welding properties of AZ31B magnesium alloy was studied by coating a layer of active agent SiC, on the base metal surface. In the experiment, the influence of various parameters on weld formation was studied by analyzing the morphology and size of the weld, and the metallographic structure, microhardness and tensile strength of the joint were analyzed. The results show that each parameter has a certain effect on the performance of the joint. (1) when the by-pass current increases from 150A to 180A, the weld penetration width and penetration depth decrease, while the residual height increases. The grain size in the weld fusion zone is reduced by measurement. The microhardness of welded joints increases gradually with the increasing of bypass current. By drawing the welded joints with different bypass currents, the tensile strength of the joints increases from 150A to 180A, and when the bypass current is 180A, (2) with the increase of welding voltage, the weld width increases, the weld depth and residual height decrease, and the weld formation is the best when the welding voltage is 23V. At the same time, the grain size also increases, but the increase is very small, which can be considered as basically unaffected. The microhardness of weld fusion zone remains basically unchanged, and the tensile strength of the joint decreases slowly, while when the voltage is 24V, the weld does not melt through and the tensile strength increases. (3) during the welding process from 2.3m/min to 2.9m/min welding, The weld width and penetration decreased gradually, while the residual height increased from the welding speed of 2.3m/min to the maximum of the welding speed of 2.7m/min, and the variation law of grain size in the weld fusion zone was the same as that of the by-pass current. The results of microhardness test and tensile test show that the microhardness and tensile strength of welded joints increase with the increase of welding speed. (4) the optimal welding parameters are as follows: main circuit current I = 230 A, bypass current I = 170 A. (5) the weld penetration depth and residual height increase gradually with the increase of SiC to 蟻 = 5.64 mg/cm2, and decrease with the further increase of SiC coating amount, but the variation of weld width is just the opposite. When the content of SiC is less than 蟻 = 5.64 mg/cm2, the grain size can be refined, and the 尾-Mg17Al12 can be dispersed in weld seam by SiC particle. The microhardness of welded joint can be improved effectively by adding SiC particles. The microhardness of the joint increases with the increase of coating amount of SiC. With the increase of SiC coating amount, the tensile strength of the joint increases. However, when the coating amount of SiC is greater than 蟻 = 5.64 mg/cm2, the tensile strength of welded joint decreases obviously.
【學(xué)位授予單位】：南昌大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG444.72
[Abstract]:In this paper, the welding of 2mm thick AZ31B magnesium alloy DE-GMAW (double electrode gas shielded welding) is studied. The influence of three welding parameters such as bypass current, welding voltage and welding speed on the weld performance is analyzed. A relatively suitable welding parameter is obtained. On the basis of these welding parameters, the effect of SiC coating amount on the welding properties of AZ31B magnesium alloy was studied by coating a layer of active agent SiC, on the base metal surface. In the experiment, the influence of various parameters on weld formation was studied by analyzing the morphology and size of the weld, and the metallographic structure, microhardness and tensile strength of the joint were analyzed. The results show that each parameter has a certain effect on the performance of the joint. (1) when the by-pass current increases from 150A to 180A, the weld penetration width and penetration depth decrease, while the residual height increases. The grain size in the weld fusion zone is reduced by measurement. The microhardness of welded joints increases gradually with the increasing of bypass current. By drawing the welded joints with different bypass currents, the tensile strength of the joints increases from 150A to 180A, and when the bypass current is 180A, (2) with the increase of welding voltage, the weld width increases, the weld depth and residual height decrease, and the weld formation is the best when the welding voltage is 23V. At the same time, the grain size also increases, but the increase is very small, which can be considered as basically unaffected. The microhardness of weld fusion zone remains basically unchanged, and the tensile strength of the joint decreases slowly, while when the voltage is 24V, the weld does not melt through and the tensile strength increases. (3) during the welding process from 2.3m/min to 2.9m/min welding, The weld width and penetration decreased gradually, while the residual height increased from the welding speed of 2.3m/min to the maximum of the welding speed of 2.7m/min, and the variation law of grain size in the weld fusion zone was the same as that of the by-pass current. The results of microhardness test and tensile test show that the microhardness and tensile strength of welded joints increase with the increase of welding speed. (4) the optimal welding parameters are as follows: main circuit current I = 230 A, bypass current I = 170 A. (5) the weld penetration depth and residual height increase gradually with the increase of SiC to 蟻 = 5.64 mg/cm2, and decrease with the further increase of SiC coating amount, but the variation of weld width is just the opposite. When the content of SiC is less than 蟻 = 5.64 mg/cm2, the grain size can be refined, and the 尾-Mg17Al12 can be dispersed in weld seam by SiC particle. The microhardness of welded joint can be improved effectively by adding SiC particles. The microhardness of the joint increases with the increase of coating amount of SiC. With the increase of SiC coating amount, the tensile strength of the joint increases. However, when the coating amount of SiC is greater than 蟻 = 5.64 mg/cm2, the tensile strength of welded joint decreases obviously.
【學(xué)位授予單位】：南昌大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG444.72
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