| Since the activating TIG welding method was put forward in the1960s, it has caused wide public concern all over the world, and a few methods were proposed one after another later on, such as A-TIG welding, FZ-TIG welding, FB-TIG welding, AA-TIG welding, however, these methods which deepen the weld penetration significantly cannot be applied widely in the actual production due to its complex operating procedure. Accordingly, the GPCA-TIG welding which is efficient, environmental and easy to facilitate automatic production is put forward here, looking forward to contributing to the real production. GPCA-TIG welding having successfully overcome the procedure difficulties mentioned above in the Carbon steel or alloy welding can control as well as adjust the introduction quantity of active elements through the adjustment of welding torch coupling degrees, realizing the control of weld property eventually.Introduction of some other elements to the outer gas has a significant impact on the welding arc and weld property. This paper studies the welding arc and weld property when the outer gas is introduced with Ar, O2, N2and the mixture of O2and N2respectively. To ensure the welding arc studied being stable and pure, water-cooled copper piece is selected as the welding arc anode, and the arc voltage and appearance accordingly are collected from fixed points. In the weld property study of the GPCA-TIG welding, the most widely used304stainless steel in industrial production is the parent mental.The welding arc is studied by spectra analysis in the GPCA-TIG welding. The calculated welding arc temperature distributions show that when the outer gas is introduced with Ar, O2, N2and the mixture of O2and N2respectively, the plasma temperature in the arc center zone increases in a certain degree compared with that of the traditional TIG welding and among these four kinds of gases, the second and the third have an obvious effect on the plasma temperature in the arc center zone and the latter has the greatest impact; when the coupling degree changes from0to+2, the impact of outer gas on the welding arc strengthens and the plasma temperature in the arc center zone increases, however, there isn’t any apparent change in the whole; the arc voltage measured increases a little compared with traditional TIG welding and the introduction of O2and N2has larger impact on the welding arc than Ar; when the coupling degree changes from0to+2, the arc voltage increases a little and that the arc appearance collected from fixed points both in the GPCA-TIG welding traditional TIG welding having no obvious change is consistent with the result that the arc temperature distribution and arc voltage alter little. Therefore, it can be concluded that during the GPCA-TIG welding, introduction of outer gas has a slight impact on the welding arc, and the arc constriction is not the main reason why the penetration increases.Study of the weld appearance and the nitrogen-oxygen contents in the weld as well as the impact toughness and tensile property of the weld in the GPCA-TIG welding shows that when the outer gas is introduced with O2only and the mixture of O2and N2respectively, the weld appearance is fine, and the8mm thick stainless steel plate could realize one side welding both sides formation, and the weld penetration is relatively narrow; when the outer gas is introduced with Ar and N2respectively, the weld penetration increases in a certain degree compared with the TIG welding but the change is little, and the weld width varies little too; when the welding torch coupling degree changes, the weld penetration and width accordingly have no apparent change. Detection of the nitrogen-oxygen contents in the weld during the GPCA-TIG welding shows that when the outer gas is introduced with O2, N2and the mixture of O2and N2, oxygen content that enters into the weld is much lower than that in the AA-TIG welding; the nitrogen-oxygen contents change with the coupling degree, and adjusting the relative position of the inner and outer nozzles of the welding torch could realize the fine control of the nitrogen-oxygen content that enter onto the weld. The measured results of low temperature impact-toughness of the weld in the GPCA-TIG welding show that the low temperature impact-toughness of the weld is lower when the outer gas is introduced with O2and N2respectively than that of the traditional TIG welding; when O2is introduced together with N2, the low temperature impact-toughness of the weld is7.5%higher than that of the parent material, and it is obviously higher than that of the traditional TIG welding; when the coupling degree changes, the nitrogen-oxygen content in the weld changes, and the low temperature impact-toughness of the weld changes accordingly, and the weld property is higher when the coupling degree is0than that when the coupling is+2. Weld tensile property measurements during the GPCA-TIG welding show that when the outer gas is introduced with O2, N2and the mixture of O2and N2respectively, the weld tensile property is a little lower than that of the parent material; when nitrogen and oxygen enter into the weld together, the weld tensile property is better than that of the traditional TIG; nitrogen and oxygen enter into the weld respectively, the weld tensile property is lower than that of the traditional TIG.The outer gas has an important impact on the welding arc and weld property in the GPCA-TIG welding, study of which enhances people’s further understanding and provides theoretical basis for its application in the industrial production, making a significant contribution to the realization of full automation, deep penetration, and high efficiency as well as low cost and high quality in GPCA-TIG welding. |
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