scholarly journals Post-Weld Heat Treatment of API 5L X70 High Strength Low Alloy Steel Welds

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5801
Author(s):  
Houman Alipooramirabad ◽  
Anna Paradowska ◽  
Shahrooz Nafisi ◽  
Mark Reid ◽  
Reza Ghomashchi
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Residual Stresses ◽  
Arc Welding ◽  
High Strength ◽  
Post Weld Heat Treatment ◽  
Slight Reduction ◽  
Weld Joints ◽  
Flux Cored Arc Welding ◽  
Weld Heat

High Strength Low Alloy (HSLA) steels are the materials of choice in pipeline construction with the API X70 grade as the steel for the majority of pipeline networks constructed during the late 20th and early this century. This paper reports on the influence of Post-Weld Heat Treatment (PWHT) on the reduction of residual stresses, resulting changes in the microstructure, and mechanical properties of a multi-pass, X70 HSLA steel, weld joints made by a combined Modified Short Arc Welding (MSAW) and Flux Cored Arc Welding (FCAW) processes. Neutron diffraction results highlighted high magnitude of tensile residual stresses, in excess of yield strength of both parent and weld metal, in the as-welded specimen (~650 MPa), which were decreased substantially as a result of applying PWHT (~144 MPa). Detailed microstructural studies are reported to confirm the phase transformation during PWHT and its interrelationship with mechanical properties. Transmission Electron Microscopy (TEM) analysis showed polygonization and formation of sub-grains in the PWHT specimen which justifies the reduction of residual stress in the heat-treated weld joints. Furthermore, microstructural changes due to PWHT justify the improvement in ductility (increase in the elongations) with a slight reduction in yield and tensile strength for the PWHT weld joint.

Post-weld Heat Treatment and Groove Angles Affect the Mechanical Properties of T92/Super 304H Dissimilar Steel Weld Joints

2018 ◽  
Vol 37 (7) ◽  
pp. 649-654 ◽  
Author(s):  
Wang Shuo ◽  
Wei Limin ◽  
Cheng Yi ◽  
Tan Shuping
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Weld Metal ◽  
Arc Welding ◽  
Post Weld Heat Treatment ◽  
Steel Weld ◽  
Dissimilar Weld ◽  
Weld Joints ◽  
Gas Tungsten Arc ◽  
Weld Heat

AbstractThe microstructures and mechanical properties of dissimilar weld joints between T92 and Super 304H steels were investigated. Dissimilar weld joints with four groove angles were constructed using gas tungsten arc welding. The results showed that post-weld heat treatment improved the mechanical properties of the dissimilar weld joints. The optimal groove angle for T92/Super 304H dissimilar weld joints was found to be 20°, considering mechanical properties. Furthermore, the transformation from equiaxed dendrites to columnar dendrites was observed in the weld metal. Epitaxial growth and delta ferrites were found around the fusion line between the Super 304H and the weld metal.

Microstructural Evolution and Resulting Mechanical Properties of Weld Joints upon Flux Cored Arc Welding and Post-Weld Heat Treatment

2009 ◽  
Vol 283-286 ◽  
pp. 439-446 ◽  
Author(s):  
Hui Yu ◽  
Kee Sam Shin ◽  
Ji Ling Dong ◽  
Dae Hwang Yoo ◽  
Woong Lee ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Impact Toughness ◽  
Arc Welding ◽  
Compositional Analysis ◽  
Post Weld Heat Treatment ◽  
Grain Structure ◽  
Automatic Welding ◽  
Weld Joints ◽  
Flux Cored Arc Welding ◽  
Weld Heat

The objective of this study is to determine the mechanism of the dramatic increase of impact toughness at low temperatures after post-weld heat treatment on weld joints. In this study, weld joints using two semi-automatic welding consumables were fabricated by flux cored arc welding with subsequent PWHT at 660°C for 65 min and 195 min, respectively. Tests of the tensile and yield strength, microhardness and impact toughness, were carried out. The microstructure was inspected by optical, scanning electron, and transmission electron microscopy in addition to compositional analysis using energy dispersive spectrometry. PWHT was observed to result in grain coarsening, sub-grain structure formation and decrease of the dislocation density. The increase of impact toughness is attributed to the relieved thermal stress, the inclusions and precipitations, softening of the structure, dislocation recovery and sub-grain structure.

Effect of Post Weld Heat Treatment on Weld Hardness Quality of P91 Welded Pipes

2015 ◽  
Vol 799-800 ◽  
pp. 377-381
Author(s):  
Mohd Amin Abd Majid ◽  
Muhammad Sarwar
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Residual Stresses ◽  
Weld Metal ◽  
Welded Joint ◽  
Post Weld Heat Treatment ◽  
Bead Geometry ◽  
Construction Sites ◽  
Weld Heat

Quality of a weld produced is generally evaluated by different parameters such as weld size, bead geometry, deposition rate, hardness and strength. A common problem that has been faced at the construction sites is to obtain a good welded joint having the required strength with minimal detrimental residual stresses to avoid any premature cracking due to high variation of hardness. In order to address this issue and to attain good weld quality, this study has been made to comprehend the effect of the post weld heat treatment on P91 material welds produced by TIG welding. Findings from the studies indicate that the PWHT has significant influence on the weld hardness of Alloy Steel-A335 P91 pipes. It is eminent that during cooling, after welding of P91, quenched martensite was formed in the HAZ that results in an increased hardness to an undesirable level of more than 250HB. PWHT at temperature of 760°C for 2 hours has good influence on mechanical properties as the hardness decreases and turns out to be uniformly distributed. If the PWHT is correctly carried out, the hardness of parent metals, heat affected zones and weld metal can be brought into the required limits to avoid any premature cracking due to high variation of hardness.

scholarly journals Effect of Post-Weld Heat Treatment Conditions on Mechanical Properties, Microstructures and Nonductile Fracture Behavior of SA508 Gr.1a Thick Weldments

2021 ◽  
Author(s):  
Junsang Lee ◽  
Jong Sung Kim ◽  
Bongsang Lee ◽  
Sungwoo Cho ◽  
Dongil Kwon ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Residual Stress ◽  
Arc Welding ◽  
Post Weld Heat Treatment ◽  
Operating Conditions ◽  
Bend Test ◽  
Welding Residual Stress ◽  
Uniaxial Tensile ◽  
Weld Heat

AbstractThis study analyzes the effects of post-weld heat treatment (PWHT) on the mechanical properties and microstructures of SA-508 Gr.1a welds and proposes a new PWHT exemption criterion based on nonductile fracture evaluation considering welding residual stress. The welding coupons were prepared with submerged-arc welding, gas-tungsten arc welding, and shielded-metal arc welding, using ferritic steel, SA-508 Gr.1a. The microstructure of the heat-affected zone (HAZ) was analyzed using optical microscopy, electron-back-scatter diffraction and Vickers hardness testing. The mechanical properties of the welds were evaluated by uniaxial tensile test, transverse side bend test, Charpy V-notch impact test and side bend test. Bainite and ferrite structures formed mainly in the HAZ, and the grain size became coarser with proximity to the surface and fusion line. The mechanical properties did not depend strongly on PWHT, weldment thickness or welding techniques, and they satisfied the welding procedure qualification test specified in the ASME Boiler & Pressure Vessel code. Welding residual stresses were considered in assessing structural integrity using nonductile fracture evaluation. A margin of safety against nonductile fracture with residual stress was calculated for Korean Standard Nuclear Power Plant steam-generator welds, using its design parameters and operating conditions, and this safety margin is suggested as an acceptance criterion for residual stress for exemption from PWHT. Graphic abstract

Effect of post-weld heat treatment (PWHT) time and multiple PWHT on mechanical properties of multi-pass TIG weld joints of modified 9Cr-1Mo steel

2014 ◽  
Vol 58 (3) ◽  
pp. 389-395 ◽  
Author(s):  
H. C. Dey ◽  
S. K. Albert ◽  
A. K. Bhaduri ◽  
G. G. Roy ◽  
R. Balakrishnan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Post Weld Heat Treatment ◽  
Weld Joints ◽  
Weld Heat
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