通过采用不同板厚的304不锈钢进行平板焊接试验和对接性试验,旨在研究不锈钢K-TIG焊接工艺的特点。针对3 mm, 5 mm, 8 mm, 10 mm厚304不锈钢平板进行焊接试验,得出了不同板厚的K-TIG临界焊接电流。进一步研究了不同焊接电流对8 mm不锈...通过采用不同板厚的304不锈钢进行平板焊接试验和对接性试验,旨在研究不锈钢K-TIG焊接工艺的特点。针对3 mm, 5 mm, 8 mm, 10 mm厚304不锈钢平板进行焊接试验,得出了不同板厚的K-TIG临界焊接电流。进一步研究了不同焊接电流对8 mm不锈钢板对接焊缝熔深的影响,当焊接电流400 A时,焊接电流相对较小电弧穿透能力偏弱尚不足以贯穿母材;当焊接电流增加到495 A时,电弧作用力增加穿透母材形成穿透的焊缝。对不同参数下的焊接电弧形态进行了观察,结果表明,提高焊接电流电弧收缩程度增加;提升钨极高度电弧收缩程度减小。展开更多
The effects of welding current on the macro-morphology, microstructure and mechanical properties of tungsten inert gas(TIG) welded AZ31 magnesium alloy joints with TiO2 coating were investigated. The results showed th...The effects of welding current on the macro-morphology, microstructure and mechanical properties of tungsten inert gas(TIG) welded AZ31 magnesium alloy joints with TiO2 coating were investigated. The results showed that the increase of welding current led to the increase in the depth/width ratio and deteriorated the surface appearance of the welded seams with TiO2 coating. The grain size of α-Mg and the amount of granular β-Mg17Al12 particles in the welded seams also increased. The welded joints with TiO2 coating exhibited a deeper weld penetration and larger grain size compared with the welded joint without TiO2 coating. When the welding current was less than 130 A, the ultimate tensile strength of the welded joints with TiO2 coating increased with the increase in welding current and then decreased when the welding current was greater than 130 A. The average microhardness of the heat-affected zone and fusion zone decreased gradually with the increase of welding current.展开更多
The main objective of this investigation is to study the influence of arc constriction current frequency(ACCF)on tensile properties and microstructural evolution of aerospace Alloy 718 sheets(2 mm in thickness)joined ...The main objective of this investigation is to study the influence of arc constriction current frequency(ACCF)on tensile properties and microstructural evolution of aerospace Alloy 718 sheets(2 mm in thickness)joined by constricted arc TIG(CA-TIG)welding process.One variable at a time approach of design of experiments(DOE)was used,in which ACCF was varied from 4 to 20 kHz at an interval of 5 levels while other parameters were kept constant.The joints welded using ACCF of 4 kHz exhibited superior tensile properties extending joint efficiency up to 99.20%.It is attributed to the grain refinement in fusion zone leading to the evolution of finer,discrete Laves phase in interdendritic areas.An increase of ACCF above 12 kHz caused severe grain growth and evolution of coarser Laves phase in fusion zone.Alloy 718 welds showed more obvious tendency for Nb segregation and Laves phase formation at higher levels of ACCF due to the slower cooling rate.The volume fraction of Laves phase was increased by 62.31%at ACCF of 20 kHz compared to that at 4 kHz,thereby reducing the tensile properties of joints.This is mainly due to the stacking of heat input in weld thermal cycles at increased levels of ACCF.展开更多
文摘通过采用不同板厚的304不锈钢进行平板焊接试验和对接性试验,旨在研究不锈钢K-TIG焊接工艺的特点。针对3 mm, 5 mm, 8 mm, 10 mm厚304不锈钢平板进行焊接试验,得出了不同板厚的K-TIG临界焊接电流。进一步研究了不同焊接电流对8 mm不锈钢板对接焊缝熔深的影响,当焊接电流400 A时,焊接电流相对较小电弧穿透能力偏弱尚不足以贯穿母材;当焊接电流增加到495 A时,电弧作用力增加穿透母材形成穿透的焊缝。对不同参数下的焊接电弧形态进行了观察,结果表明,提高焊接电流电弧收缩程度增加;提升钨极高度电弧收缩程度减小。
基金Project(51375511)supported by the National Natural Science Foundation of ChinaProjects(CDJZR12138801,CDJZR11135501,CDJZR13130033)supported by the Fundamental Research Funds for Central Universities of China
文摘The effects of welding current on the macro-morphology, microstructure and mechanical properties of tungsten inert gas(TIG) welded AZ31 magnesium alloy joints with TiO2 coating were investigated. The results showed that the increase of welding current led to the increase in the depth/width ratio and deteriorated the surface appearance of the welded seams with TiO2 coating. The grain size of α-Mg and the amount of granular β-Mg17Al12 particles in the welded seams also increased. The welded joints with TiO2 coating exhibited a deeper weld penetration and larger grain size compared with the welded joint without TiO2 coating. When the welding current was less than 130 A, the ultimate tensile strength of the welded joints with TiO2 coating increased with the increase in welding current and then decreased when the welding current was greater than 130 A. The average microhardness of the heat-affected zone and fusion zone decreased gradually with the increase of welding current.
基金This work was supported by the Indian Space Research Organization(ISRO),Department of Space,India,under ISRO RESPOND scheme(Project No.ISRO/RES/3/728/16-17).
文摘The main objective of this investigation is to study the influence of arc constriction current frequency(ACCF)on tensile properties and microstructural evolution of aerospace Alloy 718 sheets(2 mm in thickness)joined by constricted arc TIG(CA-TIG)welding process.One variable at a time approach of design of experiments(DOE)was used,in which ACCF was varied from 4 to 20 kHz at an interval of 5 levels while other parameters were kept constant.The joints welded using ACCF of 4 kHz exhibited superior tensile properties extending joint efficiency up to 99.20%.It is attributed to the grain refinement in fusion zone leading to the evolution of finer,discrete Laves phase in interdendritic areas.An increase of ACCF above 12 kHz caused severe grain growth and evolution of coarser Laves phase in fusion zone.Alloy 718 welds showed more obvious tendency for Nb segregation and Laves phase formation at higher levels of ACCF due to the slower cooling rate.The volume fraction of Laves phase was increased by 62.31%at ACCF of 20 kHz compared to that at 4 kHz,thereby reducing the tensile properties of joints.This is mainly due to the stacking of heat input in weld thermal cycles at increased levels of ACCF.
