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Welding Metallurgy of

01 Jan 1987-
About: The article was published on 1987-01-01 and is currently open access. It has received 991 citations till now. The article focuses on the topics: Welding.
Citations
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Journal ArticleDOI
TL;DR: In this paper, the effect of preheating temperature on the mechanical and fracture behavior, hardness, and the microstructure of slot welded pearlitic rail steels was studied, where the parent rail steel has ultimate strength, yield strength and strain to failure of 1146 MPa, 717 MPa and 9.3%, respectively.

15 citations


Cites background from "Welding Metallurgy of"

  • ...Microstructure of C-Mn steel weld generally consists of allotriomorphic ferrite, acicular ferrite, widmanstatten ferrite, and microphases [6-9]....

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Journal ArticleDOI
TL;DR: In this paper, a study was conducted to study liquation and liquation cracking in Mg alloys during arc welding and friction-stir welding (FSW), where binary Mg-Zn alloys were selected as a model material in view of their very low eutectic temperature of 613 K (340 K).
Abstract: As compared to Al alloys, which are known to be susceptible to liquation (i.e., liquid formation) and liquation-induced cracking, most Mg alloys have a lower eutectic temperature and thus are likely to be even more susceptible. The present study was conducted to study liquation and liquation cracking in Mg alloys during arc welding and friction-stir welding (FSW). Binary Mg-Zn alloys were selected as a model material in view of their very low eutectic temperature of 613 K (340 °C). Mg-Zn alloys with 2, 4, and 6 wt pct of Zn were cast and welded in the as-cast condition by both gas-tungsten arc welding (GTAW) and FSW. A simple test for liquation cracking was developed, which avoided interference by solidification cracking in the nearby fusion zone. Liquation and liquation cracking in GTAW were found to be in the decreasing order of Mg-6Zn, Mg-4Zn, and Mg-2Zn. Liquation cracking occurred in FSW of Mg-6Zn but not Mg-4Zn or Mg-2Zn. Instead of a continuous ribbon-like flash connected to the weld edge, small chips, and powder covered the weld surface of Mg-6Zn. The results from GTAW and FSW were discussed in light of the binary Mg-Zn phase diagram and the curves of temperature vs fraction solid during solidification.

15 citations


Cites background or methods from "Welding Metallurgy of"

  • ...Solidification cracking can be avoided to keep it from interfering with liquation cracking.([9])...

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  • ...Thus, both the formation of liquid (called liquation) and cracking induced by liquation (called liquation cracking) in Mg alloys, as will be shown subsequently, can be understood in light of those in Al alloys.([9,10]) Huang and Kou [11,12] explained that solute segregation to grain boundaries in the region next to the fusion boundary of an Al-alloy weld is caused by liquation instead of solid-state diffusion as some used to believe....

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  • ...Liquid formation (liquation) occurs in the region next to the fusion boundary that is heated to between TE and TL, that is, the partially melted zone (PMZ).([9])...

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  • ...The model is based on assumptions including negligible solid-state diffusion and negligible undercooling during solidification.([9]) Figure 15 shows the curves of temperature T vs fraction solid fS calculated for the three Mg-Zn alloys based on the Scheil solidification model, using the software package Pandat([51]) and the Mgalloy thermodynamic database PanMagnesium([52]) of CompuTherm, LLC....

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Journal ArticleDOI
TL;DR: In this paper, the effect of bonding time and solid-state homogenisation time on the microstructure and mechanical properties of AISI 304 austenitic stainless steel was investigated.
Abstract: Transient liquid phase bonding of AISI 304 austenitic stainless steel was carried out using a Co-based interlayer with 40 μm thickness. The effect of bonding time and solid-state homogenisation time on the microstructure and mechanical properties of samples was investigated. The results showed that isothermal solidification was completed within 30 min at a constant temperature of 1180°C. With increasing homogenisation time, at 1000°C, a more uniform distribution of alloying elements and hardness profile across the joint region was achieved. The average shear strength of homogenised samples was about 72% that of the base metal at the same heat treatment cycle.

15 citations


Cites background from "Welding Metallurgy of"

  • ...The first two cases occur due to significant segregation along with tensile stress, while there is no segregation in transient liquid phase (TLP) bonding because of isothermal solidification (IS) [7]....

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Dissertation
01 Jul 2012
TL;DR: In this article, the microstructural evolution of welds made between ferritic creep resistant steels that differ in chromium content was investigated, focusing on the key alloy strengthening mechanisms and the manner in which they were affected by carbon redistribution.
Abstract: This dissertation details the findings of experimental investigations of welds made between ferritic creep resistant steels that differ in chromium content. Analysis of the microstructural evolution during the application of post weld heat treatments is reported. Particular attention was paid to the key alloy strengthening mechanisms and the manner in which they were affected by carbon redistribution which takes place when these welds are exposed to high temperatures. The fusion interface regions of transition joints, made between P91 parent alloy and P22, P23 and P24 type weld consumables, were analysed in as received and post weld heat treated conditions. Carbon redistribution from the low to higher alloyed material, which resulted in its depletion from weld alloy adjacent to the fusion line, was confirmed in all weld systems subsequent to post weld heat treatment (PWHT). The effect of tempering treatments, carried out at 730°C for two and eight hour durations, on carbide populations in partially decarburised weld alloy was explored. The consequential microstructural changes, which were affected by the dissolution of M23C6 and M7C3 carbides, were compared to those observed in regions of weld alloy unaffected by carbon depletion. High resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM) were used extensively in the analysis of weld metal and heat affected zone (HAZ) microstructures. Electron diffraction and x-ray energy dispersive spectroscopy were exploited in the crystallographic and chemical characterisation of precipitates. Their evolution as a function of thermal exposure is presented for each alloy. Chemical signatures for each precipitate species, which enabled their identification, were determined for carbides in the different alloys. However, due to variations in the compositions of fusion interface M23C6 carbides, some permutations of which overlapped with compositions of M7C3, satisfactory identification demanded classification of their crystal structure. A significant difference between the microstructures of P23 and P24 alloys, in the weld specimens tested, was observed. Although vanadium and niobium carbonitrides (MX) were identified in both alloys, their distributions were not the same. Retention of carbonitride particles within partially decarburised P23 and P24 weld materials, subsequent to 8 hours post weld heat treatment, has been substantiated. Diffraction intensity distributions in Debye-Scherrer ring patterns, which were generated from MX precipitation, indicated lattice parameters varied. Microanalysis revealed that MX precipitates were present over a wide range of compositions. A combination of the composition analysis and diffraction studies indicated that MX precipitation was stable over a range of compositions in the carbon depleted regions of P24 alloy. Recrystallisation of the bainitic P22 weld alloy adjacent to the fusion line, which was accompanied by a loss of material hardness, was observed in 2 and 8 hour PWHT P91/P22 welds. It has been shown that the microstructural stabilisation of carbon depleted T/P23 and T/P24 alloys was conferred by a dispersion of MX precipitates. Retention of these stable particles, which in many cases are less than 10 nm in diameter, in carbon depleted material, resulted in the complete avoidance of any recrystallisation in 2 hour post weld heat treated T/P23 and T/P24 welds and only isolated occurrences in 8 hour tempered specimens. Subgrain size distributions were determined from electron channeling contrast images of various regions of the dissimilar metal welds. Results showed that, although recrystallisation of MX forming alloys did not occur, destabilisation of lath boundaries, due to the dissolution of M23C6 and M7C3 carbides, results in a coarser subgrain microstructure in carbon depleted P24 weld alloy. The loss of resistance to plastic deformation as a result of recrystallisation, which has been shown to take place in decarburised P22 alloy, was not observed in the alloys which precipitated the MX phase.

15 citations


Cites background from "Welding Metallurgy of"

  • ...Competitive growth of columnar grains in bulk fusion zone [75]...

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Journal ArticleDOI
TL;DR: In this paper, the effects of post weld heat treatment (PWHT) on mechanical properties and corrosion behavior of NiTi shape memory wire, laser welded to the 304 stainless steel wire were investigated.
Abstract: Effects of post weld heat treatment (PWHT) on mechanical properties and corrosion behavior of NiTi shape memory wire, laser welded to the 304 stainless steel wire were investigated. The results showed that PWHT at 200 °C increased corrosion resistance and tensile strength of the joint up to ~1.8 times that of the as-weld joint, with no heat treatment. On the contrary, precipitation of neoteric intermetallic compounds like Fe2Ti, Cr2Ti, FeNi, Ni3Ti, and Ti2Ni in the welded region deteriorated these properties, when PWHT was conducted at 400 °C. Due to the vital effects of the PWHT performed after the laser welding, careful control of the PWHT temperature was found to be a prerequisite for achievement of desirable properties in the dissimilar NiTi-304 stainless steel laser-welded wires.

15 citations

References
More filters
Journal ArticleDOI
TL;DR: In this article, the state of the art in selective laser sintering/melting (SLS/SLM) processing of aluminium powders is reviewed from different perspectives, including powder metallurgy (P/M), pulsed electric current (PECS), and laser welding of aluminium alloys.

1,172 citations

Journal ArticleDOI
TL;DR: In this article, the authors show that the pre-existing dislocation network, which maintains its configuration during the entire plastic deformation, is an ideal modulator that is able to slow down but not entirely block the dislocation motion.

557 citations

Journal ArticleDOI
TL;DR: In this article, the fundamental understanding of structure-properties relationship in automotive steels resistance spot welds is discussed. And a brief review of friction stir spot welding, as an alternative to RSW, is also included.
Abstract: Spot welding, particularly resistance spot welding (RSW), is a critical joining process in automotive industry. The development of advanced high strength steels for applications in automotive industry is accompanied with a challenge to better understand the physical and mechanical metallurgy of these materials during RSW. The present paper critically reviews the fundamental understanding of structure–properties relationship in automotive steels resistance spot welds. The focus is on the metallurgical characteristics, hardness–microstructure correlation, interfacial to pullout failure mode transition and mechanical performance of steel resistance spot welds under quasi-static, fatigue and impact loading conditions. A brief review of friction stir spot welding, as an alternative to RSW, is also included.

369 citations

Journal ArticleDOI
TL;DR: In this article, a unified equation to compute the energy density is proposed to compare works performed with distinct equipment and experimental conditions, covering the major process parameters: power, travel speed, heat source dimension, hatch distance, deposited layer thickness and material grain size.

369 citations

Journal ArticleDOI
TL;DR: This study attempted to predict solidification defects by DNN regression with a small dataset that contains 487 data points and found that a pre-trained and fine-tuned DNN shows better generalization performance over shallow neural network, support vector machine, and DNN trained by conventional methods.

314 citations