Showing papers in "Welding International in 1994"
TL;DR: The physics of welding (III) as discussed by the authors, Melting rate and temperature distribution of electrode wire in welding, is a classic example of such an approach. But it is not suitable for high-pressure welding.
Abstract: (1995). Physics of welding (III) ‐ Melting rate and temperature distribution of electrode wire. Welding International: Vol. 9, No. 5, pp. 348-351.
26 citations
16 citations
TL;DR: In this article, an automatic welding system that can simultaneously control the bead height and back bead shape during one-sided MAG welding with a backing plate is described, which uses a high-speed rotating arc welding process together with an arc sensing technique for seam tracking and torch height control.
Abstract: Summary This paper describes an automatic welding system that can simultaneously control the bead height and back bead shape during one‐sided MAG welding with a backing plate. The system uses a high‐speed rotating arc welding process together with an arc sensing technique for seam tracking and torch height control. The arc sensing technique is also used to detect variations in the groove shape. The detection mechanism is described in detail in this paper. The system further uses a newly developed welding parameter control method in which only the wire feedrate and welding voltage are adaptively controlled, the other welding conditions being kept constant. This method is able to keep the bead height constant and retain the back bead shape even if the groove shape changes. Initial welding experimental results have shown the system to be effective and satisfactory for controlling the weld bead shape in one‐sided GMAW (MIG/MAG) with a backing plate.
14 citations
TL;DR: In this paper, a type 329J1 duplex stainless steel was welded by single pass gas tungsten arc welding in an argon-nitrogen mixed gas atmosphere, and the microstructure, Vickers hardness, and Charpy impact toughness of the weld metal were examined.
Abstract: Summary A type 329J1 duplex stainless steel was welded by single‐pass gas tungsten arc welding in an argon‐nitrogen mixed gas atmosphere. The microstructure, Vickers hardness, and Charpy impact toughness of the weld metal were examined. The nitrogen content increases and the ferrite content decreases with increasing nitrogen partial pressure of the atmosphere. The ferrite content linearly decreases with an increasing nitrogen content. The hardness of the ferrite and austenite phases is virtually constant regardless of the weld metal nitrogen content. The toughness increases with the nitrogen content at room temperature and above, remaining constant at lower temperatures. The weld metal toughness is affected by the presence of austenite and chromium nitride precipitates in the ferrite. The nitrogen absorption of duplex stainless steel weld metal improves the impact toughness through an increase in the austenite content and a decrease in the amount of nitride.
13 citations
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TL;DR: In this paper, a temperature measurement test by the UV spot sensor (spectral range: 0.25 μm) showed that the melting point of Ni can be measured with an accuracy of ± 1 % regardless of any emissivity fluctuation.
Abstract: Summary Accurate measurement of temperature is of considerable importance in materials processing, such as welding, thermal cutting, and heat treatment of metals. Radiation thermometry has a distinct advantage over other temperature detection methods, since it requires no physical contact with the work. The reliability of thermometry, however, is limited if the emissivity of the work to be measured is not accurately known. Planck's law of radiation shows that the effect of temperature on the spectral radiance is greater at shorter wavelengths. The present paper experimentally describes the characteristics of UV (ultraviolet) thermometry. A temperature measurement test by the UV spot sensor (spectral range: 0.25 μm) shows that the melting point of Ni can be measured with an accuracy of ± 1 % regardless of any emissivity fluctuation. The CCD camera with UV filter used in this investigation makes it possible to detect the temperature image on the work in welding virtually independently of the emissivity of t...
8 citations
TL;DR: In this paper, a manual underwater welding structure of steel with higher strength is presented. But this method is not suitable for the underwater welding of large steel structures, as shown in Figure 1.
Abstract: (1994). Manual underwater welding structures of steel with higher strength. Welding International: Vol. 8, No. 1, pp. 43-46.
TL;DR: In this paper, the authors used a 22kW ETCA laser to achieve efficiency for large thicknesses and quality of execution using a camera examining the molten pool, which gave encouraging results.
Abstract: Synopsis Efficiency for large thicknesses and quality of execution are attainable using a 22kW ETCA laser. Operating conditions are adjusted and causes of imperfections are identified by means of a camera examining the molten pool. Tests to define the mechanical properties give encouraging results.
TL;DR: In this paper, the internal microstructure, chemical composition, and hardness of the martensite-austenite constituent formed in one type of simulated HAZ was investigated in 780 and 980 MPa class HSLA steels.
Abstract: Summary This paper describes an investigation of the internal microstructure, chemical composition, and hardness of the M‐A (martensite‐austenite) constituent formed in one type of simulated HAZ ‐ the CGHAZ (coarsegrained HAZ for high heat input welding process) ‐ in 780 and 980 MPa class HSLA steels to determine the metallographic characteristics of the M‐A constituent. The M‐A constituent is classified into two morphological types: massive M‐A and elongated M‐A. The massive M‐A constituent has a higher C content and includes more twin type martensite and retained austenite than the elongated M‐A. The cementite is classified into a coarse rod type and dendritic or acicular type. The coarse rod type is considered to be precipitated directly from the austenite. The dendritic or acicular type is probably precipitated by self‐tempering of the martensite. The C content of the M‐A constituent increases with ?t[8/5 (cooling time from 1073 to 773 K), reaching 1.3–2.2% when ?t8/5 = 100–1000 sec. The hardness of t...
TL;DR: In this paper, a combination of low frequency switching pulsed GMA welding and a new trial-manufactured Zr-added Al-7%Mg wire was used for grain refinement and solidification crack susceptibility.
Abstract: Summary The grain refinement and solidification crack susceptibility of GMA. (MIG) weld metal produced with Al‐4.5%Zn‐1.2%Mg A7N01 base metal have been successfully improved by a combination of low‐ frequency switching pulsed GMA welding and a new trial‐manufactured Al‐ 7%Mg welding wire containing added Zr as a microalloying element. The results show a close relationship between the grain size of the weld metal and the crack susceptibility, with a sharp reduction in the crack susceptibility being obtained in weld metal with fine equiaxed grains of 20–30 m dia. The pronounced grain refinement can only be obtained by a combination of low‐frequency pulsed GMA welding at a switching frequency of 2.5–50 Hz and trial‐manufactured Zr‐added Al‐7%Mg wire. Little grain refinement is found with Zr‐free wire. The paper discusses the relation‐ ship between grain refinement and the oscillation behaviour of the molten pool due to current pulsation.
TL;DR: In this paper, an experimental and numerical analysis of residual stresses in welded AI•5083•O aluminium plates is presented. But the analysis is limited to the case of welded aluminum plates.
Abstract: (1994). Experimental and numerical analysis of residual stresses in welded AI‐5083‐O aluminium plates. Welding International: Vol. 8, No. 1, pp. 30-35.
TL;DR: In this paper, the physical properties of liquid metals, including surface tension and electronic transport properties, have been investigated in the context of liquid metal fabrication. But they did not consider the electronic properties of the liquid metal.
Abstract: (1994). Physical properties of liquid metals [IV] surface tension and electronic transport properties of liquid metals. Welding International: Vol. 8, No. 10, pp. 766-770.
TL;DR: In this article, the authors describe efforts to fabricate explosively welded Al/Cu clad through insertion of a Cu intermediate plate between the Al driver and the base plates, which is effective as a means of reducing the energy dissipated by collision.
Abstract: Summary This paper describes efforts to fabricate explosively welded Al/Cu clad through insertion of a Cu intermediate plate between the Al driver and Cu base plates. In explosively welded Al/Cu clad fabricated by the conventional method, generation of an excess reacted interfacial zone causes degradation of bonding properties. Application of a Cu intermediate plate is effective as a means of reducing the energy dissipated by collision. The effect of the kinetic energy lost by collision on the thickness of the reacted interfacial zone and on the bond strength are examined in experiments with stainless steel. Efforts are made to fabricate Al/Cu conductive transition joints of commercial size with a Cu intermediate plate. The bonding properties obtained are better than those obtained by the conventional method.
TL;DR: In this paper, the authors describe an investigation of hard surfacing of aluminium alloy by conventional pulsed and low-frequency pulsed MIG welding using a newly developed seamless cladding wire (copper sheath with solid aluminium wire as the inside core) of 1.6 mm diameter.
Abstract: Summary This paper describes an investigation of hard surfacing of aluminium alloy by conventional pulsed and low‐frequency pulsed MIG welding using a newly developed seamless cladding wire (copper sheath with solid aluminium wire as the inside core) of 1.6 mm diameter. Two cladding wires with different copper contents (34mass%Cu and 52mass%Cu) were tested. The effect of the shielding gas on the hardening characteristics and blowhole generation was also investigated. A Vickers hardness of Hv160–280 is obtained, being some 2–3 times greater than that of the base metal. Micro‐blowholes not detected by radiographic inspection mostly occur in the weld metal, tending to decrease with an increasing mixing ratio of helium gas.
TL;DR: In this paper, the authors studied the thermal phenomena during friction welding and the mechanical properties of an aluminium alloy and found that the properties of the alloy are similar to those of a steel alloy.
Abstract: (1994). Study of thermal phenomena during friction welding and the mechanical properties of an aluminium alloy. Welding International: Vol. 8, No. 5, pp. 349-353.
TL;DR: In this article, chemical elements affecting the weldability of Al-Mg-Li alloys are discussed and a detailed discussion of the effects of chemical elements on the weld ability of alloys is presented.
Abstract: (1994). Chemical elements affecting the weldability of Al‐Mg‐Li alloys. Welding International: Vol. 8, No. 9, pp. 725-727.