Multipass pulsed current gas metal arc welding of P91 steel

Krishnan, S.; Kulkarni, D. V.; De, A.

doi:10.1179/1362171815y.0000000080

Cited by 10 publications

(4 citation statements)

References 33 publications

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“…The deposition rate with flux cored wire was increased by about 42% compared to the use of a common solid wire, considering the same set of parameters and welding conditions. Other authors using the same process reported a significant decrease in the defects generated during the welding process, namely spatter, welding porosity, and lack of fusion decreasing, as well the weld width [7,8]. Other processes such as shielded metal arc welding (SMAW), submerged arc welding (SAW), and flux cored arc welding (FCAW) have also been tested to maximize the welding efficiency of P91 steels, but non-metallic inclusions have been observed in the weld beads, loss of toughness, and excessively high oxygen content in the welds, considering the studies conducted during the 2000-2009 decade [9,10].…”

Section: Introductionmentioning

confidence: 85%

Evaluation of Welded Joints in P91 Steel under Different Heat-Treatment Conditions

Silva

Pinho

Péreira

et al. 2020

Metals

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P91 steel has been of interest to many researchers over the past two decades. This interest is because this steel has very interesting characteristics for application in power plants, where it is common to have pipes that need to support steam at temperatures between 570 and 600 °C, and at pressures in the range of 170 to 230 bar. These working conditions are quite severe for most common steels, requiring increased high-temperature mechanical strength as well as high creep resistance. The manufacture of these pipes normally includes welding operations, which must preserve the main characteristics of this type of steel. This justifies the concern of the researchers to ensure the best welding conditions so that the preservation of the properties of these steels becomes possible. The present work intends to depict the best results obtained varying the heat-treatment conditions applied to weldments made on heat-resistant steel P91. This steel usually takes the designation SA 213 T91 (seamless tube) or SA 335 P91 (seamless pipe), according to ASME II, as well as the designation X10CrMOVNb9-1 according to EN 10216-2. The purpose of this study is to compare the behavior of pipe welding under different post-welding heat-treatment (PWHT) conditions. One of them is performed with thermal cycles (preheating, post-heating, and the post-weld heat treatment) in agreement with most construction codes and standard rules. The second one is performed without any thermal cycle before and after welding. Both welds were made by the same process, TIG (Tungsten Inert Gas, or GTAW—Gas Tungsten Arc Welding) in the horizontal position (2G according to ASME IX) and the same welding parameters. In order to evaluate the results obtained in the welds, microstructure analyses, hardness measurements, bending tests, and tensile tests at room and high temperature (600 °C) have been performed. Other tests were also carried out according to the quality procedures, such as visual, penetrant dye, and X-ray tests. Regarding the different strategies used in the heat treatments, the best results have been obtained using a strategy similar to the one currently in use and recommended by construction codes and steel manufacturers but excluding the phases’ transformation time, and it was possible to observe that the tensile strength is impaired by about 2% to 9% at room and elevated temperatures, respectively; the elongation is reduced by 39% at room temperature but keeps a good performance at elevated temperature; the hardness profile is very similar at both temperatures; the microstructure presented is compatible with the requirements; and no cracking trend has been reported. Thus, a new strategy for the welding heat treatment of grade 91 steels was drawn, saving energy and processing time.

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Section: Introductionmentioning

confidence: 85%

Evaluation of Welded Joints in P91 Steel under Different Heat-Treatment Conditions

Silva

Pinho

Péreira

et al. 2020

Metals

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“…Welding, microstructures, mechanical properties, and PWHT of P91 steel have attracted a lot of attention in recent years. Up to now, welds made with different welding processes, including laser and electron beam welding, different welding parameters [9,[14][15][16][17][18], welding process efficiency [19], effects of preheat temperatures and interpass temperatures [20], defects in welds [21,22], tribological properties [23], fatigue behavior [24], and effects of creep [25][26][27] were studied thoroughly. A critical issue that limits the creep strength of P91 weldments under service conditions is type IV cracking [28,29].…”

Section: Introductionmentioning

confidence: 99%

Optimization of PWHT of Simulated HAZ Subzones in P91 Steel with Respect to Hardness and Impact Toughness

Lojen

Vuherer

2020

Metals

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Appropriate post weld heat treatment (PWHT) is usually obligatory when creep resistant steels are welded for thermal power plant components that operate at elevated temperatures for 30-40 years. The influence of different PWHTs on the microstructure, hardness, and impact toughness of simulated heat affected zone (HAZ) subzones was studied. Thereby, coarse grained HAZ, two different fine grained HAZ areas, and intercritical HAZ were subjected to 20 different PWHTs at temperatures 740–800 °C and durations 0.5–8 h. It was found that the most commonly recommended PWHT, of 3 h or less at 760 °C, is insufficient with respect to the hardness and impact toughness of coarse grained HAZ. To obtain a Vickers hardness ≤ 265 HV and impact toughness at least equal to the impact toughness of the base metal (192 J) in the coarse grained HAZ, it took 8 h at 740 °C, 4 h at 760 °C, more than 1 h at 780 °C, and 0.5 h and 800 °C. Even after 8 h at 800 °C, mechanical properties were still within the target range. The most recommendable post weld heat treatments at 780 °C for 1.2–2 h or at 760 °C for 3–4 h were identified. All specimens subjected to these treatments exhibited appropriate hardness, impact toughness, and microstructure.

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“…It is the main welding structural material in the field of aerospace manufacturing and transportation. Among various welding methods of aluminum alloys, metal inert gas (MIG) welding has the advantages of easy automation and high production efficiency, and it has become the most widely used welding method for aluminum alloys [1][2][3][4]. MIG welding technology can achieve single side welding and double side forming for the 10 mm thick 7A52 aluminum alloy, and it greatly improves the welding production efficiency.…”

Section: Introductionmentioning

confidence: 99%

7A52 Aluminum Alloy MIG Welding Residual Stress Reliable Measurement based on Hole-Drilling Method

Gan¹

2019

IJPE

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To analyze the welding residual stress distributions for aluminum alloy medium and thick plates after the process of MIG welding, a residual stress testing system based on hole-drilling method was designed by virtual instrument and NI data acquisition card. To improve the accuracy and reliability of measurement results, the elasticity modulus error, strain gauge pasted error, and strain reading value time error were emphatically analyzed. The elasticity modulus error could be corrected by the curve that is fit to data measured in different MIG welding joint areas. The final measurement error caused by the strain gauge pasted error was reduced to 0 in 24 hours after the strain gauge was pasted. The final measurement error caused by the strain reading value time error was reduced to 0 in 150 minutes after the residual stress began to be measured. The experiment of MIG welding residual stress measurement was carried out on 10 mm thick 7A52 aluminum alloy plates. The results showed that the distributions of residual stresses on two sides of the weld seam were basically symmetrical about the weld center. The maximum tensile stress appeared in the fusion zone, and the maximum transverse residual stress y  and the maximum longitudinal residual stress x  were 96 MPa and 185 MPa, respectively. The residual stresses from the fusion zone to heat affected zone were all tensile stresses, which were higher than the residual stresses in the center of the welding seam. Smaller compressive stresses appeared in the base metal.

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Multipass pulsed current gas metal arc welding of P91 steel

Cited by 10 publications

References 33 publications

Evaluation of Welded Joints in P91 Steel under Different Heat-Treatment Conditions

Evaluation of Welded Joints in P91 Steel under Different Heat-Treatment Conditions

Optimization of PWHT of Simulated HAZ Subzones in P91 Steel with Respect to Hardness and Impact Toughness

7A52 Aluminum Alloy MIG Welding Residual Stress Reliable Measurement based on Hole-Drilling Method

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