A‐TIG welding of UR 52N+ superduplex stainless steel

Summary

The improved performance due to the use of flux in automatic welding of a superduplex stainless steel with the A‐TIG process is presented. The flux used during welding enables molten pool depth to be increased in a single pass, with complete penetration of a plate 5.6 mm thick and without edge preparation. Welding energy is located in the range of values recommended for this type of steel. The beads obtained were observed using optical micrography and were subjected to mechanical and corrosion tests, as well as ferrite content measurement testing. In addition, the influence of flux grain measurement and the nature of welding gas on flux effectiveness were studied. These tests reveal that the use of flux not only enables superduplex stainless steels 5.6 mm thick to be welded in a single pass but it also improves mechanical properties, corrosion characteristics and austenite content of welded joints, while maintaining an austenite volume fraction identical to that of the parent metal.     

A study on twin-tungsten TIG welding method

A new twin-tungsten TIG （T-TIG） welding method was studied. This method differs from the conventional TIG method, it places two electrodes insulated from each other in the same welding torch, and a coupling arc is generated from the two electrodes. The coupling arc pressure was measured and preliminary welding experiment was made. The results show that the coupling arc can keep arc pressure at a low level compared with conventional TIG arc, and welding can be achieved under higher current and high travel speed with sound appearance of weld. Therefore, this new method can applied widely in high effwiency welding.     

Effects of electrode tip shape and torch angle on high‐speed DCEN TIG welding

An investigation was conducted in order to determine the effect of both the metallic transfer mode (pulsed arc or short circuit) and the O₂ content in the Ar/O₂ gas mixture, of the gas-metal arc welding process (GMAW), on the fatigue life under uniaxial conditions of welded joints of 316L stainless steel. It was concluded that the mixture of the shielding gases employed in the process could have an important influence on the fatigue life of the welded joints of such steel in two different ways. Firstly, through the modification of the radius of curvature at the joint between the welding toe and the base metal and, secondly, through a more pronounced degree of oxidation of the alloying elements induced by a higher O₂ content in the mixture. As far as the metallic transfer mode is concerned, it has been determined that the welded joints obtained under a pulsed arc mode show a greater fatigue life in comparison with the joints obtained under short circuit for both gas mixtures.     

Study on arc-ultrasonic TIG welding of titanium alloy

TCA alloy was welded by conventional TIG welding and arc-ultrasonic TIG welding respectively. The microstructure of joint was analyzed by means of optical-microscope, scanning electron microscope in order to study the relationship between the macro-properties of joint and the microstructure. The results show that the joints were all welded successfully by conventional TIG welding and arc-ultrasonic TIG welding. With the increment of ultrasonic frequency and activated voltage, the width of joint became narrow step by step. The microstructure became more and more fine and was inclined to equiaxed crystal. Moreover, the dendrite depredation was not observed obviously. The properties of welded joint were improved markedly compared with that of conventional TIG welding.     

YAG laser welding with surface activating flux

YAG laser welding with surface activating flux has been investigated, and the influencing factors and mechanism are discussed. The results show that both surface activating flux and surface active element S have fantastic effects on the YAG laser weld shape, that is to obviously increase the weld penetration and D/W ratio in various welding conditions. The mechanism is thought to be the change of weld pool surface tension temperature coeffwient, thus, the change of fluid flow pattern in weld pool due to the flux.     

Non‐copper‐coated solid wire for MAG welding

In the modern manufacturing sector, new materials and current fabrication technologies force a critical re-examination of all conventional knowledge. Increasing production and reducing waste remain fundamental objectives for every business: the trend is moving towards increasingly reduced labour, which is gradually being replaced by automation. On the other hand, especially in such a fundamental sector as the automotive industry, there is a prime requirement: reduced vehicle weight, due to the incessant demand for energy and cost savings, in addition to meeting commitments relating to harmful emissions and environmental protection. The metallurgical development of high-strength steels has allowed the use of new materials with increasingly enhanced mechanical characteristics, benefiting mankind with increased safety and the ability to absorb ever greater quantities of energy without cracking. To analyse the problems associated with the types of welding used with increasing frequency in the automobile sector, research has been focussed on joints made between conventional materials such as S355 steel and high-strength Dual Phase steels. This study has attempted to highlight the use of a welding robot in a mass production setting, and to study the best welding parameters when not working with components with the same metallurgical characteristics. Furthermore, the ability to obtain good quality welds when there are geometrical problems, such as misalignments between the pieces to be welded, has been evaluated.     

Observations on welding of  2+O+&bgr; titanium aluminide

Abstract

The weldability characteristics of an  ₂+O+&bgr; titanium aluminide of nominal composition Ti–24Al–15.5Nb (at.-%) have been investigated. Conventional gas tungsten arc (GTA) and electron beam (EB) welds exhibited columnar fusion zone grains. Pulsed current and arc oscillated GTA welds exhibited predominantly equiaxed fusion zone grains. The microstructure of GTA welds and pulsed current GTA welds exhibited  ₂+O phases, whereas arc oscillated GTA welds and EB welds contained  ₂+O+&bgr; ₀/&bgr; ₂; however, &bgr; ₀/&bgr; ₂ is predominant in EB welds. The EB welds, which contained  ₂+&bgr; ₀/&bgr; ₂ microstructure, exhibited high strength and ductility compared with GTA welds. The observed microstructural variations are explained on the basis of possible weld thermal cycles and convective currents in the weld pool.     

厚板铝合金MIG+TIG双枪焊接工艺

针对厚板铝合金焊接采用MIG+TIG双枪焊接技术,设计V型、X型两种坡口形式,使用直径Ф2.0 mm的焊丝进行了工艺研究。通过对试板力学性能、无损检测等方面检测,研究发现,在此工艺条件下,X型坡口设计能够更好的满足检测试验,V型坡口则存在一定的风险。X型坡口铝合金焊缝平均抗拉强度为295 MPa,为母材强度的86.7%。     

An initial study on welding procedure using tandem MIG welding of high strength aluminum alloy

The high-speed camera system and data acquisition system of welding parameters were created in tandem MIG welding of high strength aluminum alloy. The experiments were carried out in order to obtain the photos of droplet transfer under different welding parameters in pulsed mode. The droplet transfer mode of ““one pulse one droplet““ becomes the preferred selection during welding process because of its stable procedure and sound weld form. The parameter ranges for corresponding transfer mode were experimentally achieved, among which the stable droplet transfer mode of ““one pulse one droplet““ can be realized. These efforts brave the way for control weld heat input and weld formation in the future.     

Physics characteristic of coupling arc of twin-tungsten TIG welding

1 Introduction It is well known that high effeciency and high quality welding is the developing target of welding technology[1, 2]. TIG welding is one of the high quality and widely applied welding methods because its arc is stable, its precess is easy t…     

Self-adjusting dynamic characteristics of pulsed MIG welding for aluminum alloys

Pulsed MIG welding is suitable for aluminum alloys welding, because spray transfer and excellent profile can be arrived during whole welding current range, and the energy of droplet can be controlled to overcome losing of alloy elements with lower melting and steam point by controlling pulse current and pulse time. Because of the special physic properties of aluminum alloys, there are different requirements for pulsed MIG welding between starting arc short circuit and drop transfer short circuit, pulse period and base period. In order to satisfy the need of aluminum alloys MIG welding, self-adjusting dynamic characteristics are designed to output different dynamic characteristics in different welding startes. The self-adjusting dynamic characteristics of pulsed MIG welding are achieved through a short circuit controller and a dynamic electronic inductor. The welding machine(AL-MIG 350) with self-adjusting dynamic characteristics has a high rate of successfully starting arc up to 96%, and the short circuit time during transfer is less than 1ms, in the mean time, the arc is stiffness, spatter is low and weld appearance is good.     

YAG激光与脉冲MIG复合焊接

研究了YAG(掺钕钇铝石榴石 ,Nd 3:Y3Al5O1 2 )激光与脉冲MIG电弧复合焊接铝合金的新工艺 ,设计制造了复合焊接机头 ,探讨了各种规范参数对焊缝成形的影响规律及激光与电弧的复合作用。结果表明 ,在比较宽的参数范围内YAG激光 -脉冲MIG复合焊接铝合金焊缝成形美观 ,无气孔等缺陷 ,熔深与激光单独焊比增加 4倍 ,与脉冲MIG焊接比增加 1倍以上 ,焊速显著提高 ,是一种理想的焊接工艺。     

TIG—MIG焊管机的微机闭环程序控制

自动 TIG 焊打底、MIG 焊盖面(简称 TIG—MIG 焊)管对接焊机,是一种比较先进的管对接焊机,它对焊接过程的电气控制要求较高,主要是要求在管子转动至若干不同位置时,焊机产生一系列相应的动作,以保证焊接过程顺利进行。     

Fabrication of structures by upsetting‐pressure welding

Results of investigations into the mechanical and corrosion properties and structure of friction stir welded joints in V95 alloy of the Al–Zn–Mg–Cu system are presented. It is shown that friction stir welding produces high-strength high-quality welded joints in welding of the ‘unweldable’ alloy, and the properties are determined by the condition of the heat-affected zone. It is also shown that a non-recrystallized structure forms in the core of the welded joints and the most probable mechanism of the formation of the ultrafine-grained equiaxed structure is collective dynamic polygonization and not dynamic recrystallization.     

Braze‐welding of electrical conductors to concentric plugs

In resistance spot welding of thin sheet–thick sheet–thick sheet joint, when the sheet thickness ratio is large (sheet thickness ratio = total thickness of sheet joint/thickness of the thin sheet positioned on the outside of the joint), how to stably secure the nugget between the thin sheet and the adjoining thick sheet is a key issue. If the sheet thickness ratio is so large, nugget formation between the thin sheet and thick sheet is extremely difficult. In order to control of the nugget (position of formation, shape, etc. of the nugget) during welding for three sheets joint with a high sheet thickness ratio, optimum welding process was investigated. The developed ‘two-step force, two-step current’ welding process was suitable for high sheet thickness ratio joint and relaxed the constraints on the sheet thickness ratio. In Step 1 (first part of welding period) of the welding process, a nugget is reliably formed between the thin sheet and thick sheet by applying conditions of low electrode force, short welding time, and high current. In the subsequent Step 2 (second part of welding period), a nugget is formed between the two thick sheets by applying high welding force and a long welding time. In the weld results of a three sheet joint (0.7+2.3+2.3 mm; sheet thickness ratio: 7.6) using mild steel GA (0.7 mm) as the thin sheet and 780 MPa high strength GA (2.3 mm) in the two thick sheets, ‘two-step force, two-step current’ spot welding process showed the wide available welding current range.     

交替式TIG—MIG焊电弧现象及其相互影响

1.引盲普通的 TIG 焊钨极产生一个稳定的电弧,但是焊缝金属的熔敷率太小。与此相反,普通的 MIG 焊有较高的焊缝金属熔敷率,但电弧不够稳定。如果 MIG 焊丝能够放到稳定的 TIG 弧附近,那么就能得到具有稳定的焊接电弧、较高的焊缝金属熔敷率和高质量的焊缝。然而,当两个电弧放到一起时,由于磁场的存在,它们之     

6061铝合金MIG/TIG焊接接头性能对比研究

针对6061铝合金分别开展了3 mm厚板MIG焊和TIG焊的焊接试验,并对焊接接头进行了强度测试和金相组织观察。结果表明,在所选取合适的焊丝和焊接工艺参数下,均获得了性能优良的焊接接头,其中TIG焊接头由于热输入量较大生成了粗大的铸态组织,从而导致MIG焊接头强度要略高于TIG焊接头的强度。     

Research on menu-typed man-machine interaction system of digital TIG welding machine

A digital matt-machine interaction system controlled by communications between two processors of TMS320F240 and A/98C2051 was researched in the paper. The system is easy to set and modify welding process parameters by keyboards, and display information of welding site by LCD (Liquid Crystal Display). As one part of multi-task system about TIG welding machine, the coordination of man-machine interaction system with other tasks is the main point to the stability and reliability of its operation. Experiments result indicates that the system is stable, operation-flexible, high precision, and anti-interfering.     

Simulation on temperature field of TIG welding of copper without preheating

1 Introduction Fusion welding of red copper easily leads to many defects, such as backing’s lack of fusion, groove’s hard of through-welding, bad surface forming. All these have relations with thermophysical performances of red copper. The heat conduct…