An Arrhenius equation-based model to predict the residual stress relief of post weld heat treatment of Ti-6Al-4V plate

2018 ◽  
Vol 32 ◽  
pp. 763-772 ◽  
Author(s):  
Guangxu Yan ◽  
Alexandru Crivoi ◽  
Yajuan Sun ◽  
Niroj Maharjan ◽  
Xu Song ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Arrhenius Equation ◽  
Stress Relief ◽  
Post Weld Heat Treatment ◽  
Weld Heat

Residual Stress Relaxation in a Tube Attachment Weld Inside a Pressure Vessel Forging During Post Weld Heat Treatment

2007 ◽  
Author(s):  
P. R. Hurrell ◽  
J. Davies ◽  
N. A. Leggatt ◽  
R. J. Dennis ◽  
R. H. Leggatt
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Stress Relaxation ◽  
Pressure Vessel ◽  
Hold Time ◽  
Stress Relief ◽  
Post Weld Heat Treatment ◽  
Secondary Creep ◽  
Axial Tensile ◽  
Weld Heat

This paper presents analyses done to determine residual stress relief achieved by post weld heat treatment (PWHT) of tube attachment welds inside a thick SA508 steel pressure vessel forging. Finite element (FE) analyses were performed modelling the manufacturing operations in detail including welding, machining and PWHT. The analyses demonstrate that PWHT at 600°C for 8 hours is effective in reducing as-welded residual stress levels from tensile yield magnitude (+500MPa approx) to <100MPa. The maximum residual stress was computed to be 90MPa sub-surface in a region of hydrostatic (tri-axial tensile) stress. Secondary creep was modelled using data from creep tests on SA508 steel uni-axial tensile specimens. Practically all of the stress relaxation is due to creep strain with minimal additional plastic strain. Most stress relief occurs during the first hour of soak, with diminishing benefit thereafter. Analysis results also indicate that PWHT effectiveness is more sensitive to soak temperature than hold time. These FE results are considered slightly pessimistic but are reasonably consistent with other analytical predictions. By comparison surface hole drilling stress measurements of <50MPa (10% yield strength) were recorded from a representative welded test block. Analysis pessimism was attributed to ignoring both primary creep and relaxation during the slow warm up phase of the heat treatment cycle.

Residual Stress Relief in Post-Weld Heat Treatment

2008 ◽  
Author(s):  
Pingsha Dong ◽  
Jeong K. Hong
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Stress Relief ◽  
Heating Time ◽  
Post Weld Heat Treatment ◽  
Weld Residual Stress ◽  
Pressure Vessel Steels ◽  
Parametric Analyses ◽  
Holding Temperature ◽  
Weld Heat

This paper focuses on analysis of weld residual stress relief process during furnace-based uniform post-weld heat treatment (PWHT). Two classes of pressure vessel steels: 2-1/4CrMo and carbon steel are considered in seam weld configurations. It is found that the dominant mechanism for residual stress relief is the creep relaxation that occurs much earlier during a PWHT cycle than typically expected. This phenomenon is further confirmed by experimental data. After a large number of parametric analyses of various PWHT parameters, a simple form of relationship is proposed for relating residuals stress relief to a set of PWHT parameters for the two classes of steels. These parameters include PWHT ramp-up heating time, PWHT holding time, PWHT holding temperature, and weldment thickness.

scholarly journals Optimization Study of Post-Weld Heat Treatment for 12Cr1MoV Pipe Welded Joint

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 127
Author(s):  
Zichen Liu ◽  
Xiaodong Hu ◽  
Zhiwei Yang ◽  
Bin Yang ◽  
Jingkai Chen ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Stress Reduction ◽  
Simulation Method ◽  
Post Weld Heat Treatment ◽  
Residual Stress Field ◽  
Element Analysis ◽  
Tempering Treatment ◽  
Temper Heat Treatment ◽  
Weld Heat

In order to clarify the role of different post-weld heat treatment processes in the manufacturing process, welding tests, post-weld heat treatment tests, and finite element analysis (FEA) are carried out for 12C1MoV steel pipes. The simulated temperature field and residual stress field agree well with the measured results, which indicates that the simulation method is available. The influence of post-weld heat treatment process parameters on residual stress reduction results is further analyzed. It is found that the post weld dehydrogenation treatment could not release residual stress obviously. However, the residual stress can be relieved by 65% with tempering treatment. The stress relief effect of “post weld dehydrogenation treatment + temper heat treatment” is same with that of “temper heat treatment”. The higher the temperature, the greater the residual stress reduction, when the peak temperature is at 650–750 °C, especially for the stress concentration area. The longer holding time has no obvious positive effect on the reduction of residual stress.

scholarly journals Residual Stress State of X65 Pipeline Girth Welds Before and After Local and Furnace Post Weld Heat Treatment

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Yao Ren ◽  
Anna Paradowska ◽  
Bin Wang ◽  
Elvin Eren ◽  
Yin Jin Janin
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Residual Stresses ◽  
Outer Surface ◽  
Post Weld Heat Treatment ◽  
Pipe Length ◽  
Stress Profiles ◽  
Girth Welds ◽  
Welded Pipe ◽  
Weld Heat

This research investigated the effects of global (in other words, furnace-based) and local post weld heat treatment (PWHT) on residual stress (RS) relaxation in API 5L X65 pipe girth welds. All pipe spools were fabricated using identical pipeline production procedures for manufacturing multipass narrow gap welds. Nondestructive neutron diffraction (ND) strain scanning was carried out on girth welded pipe spools and strain-free comb samples for the determination of the lattice spacing. All residual stress measurements were carried out at the KOWARI strain scanning instrument at the Australian Nuclear Science and Technology Organization (ANSTO). Residual stresses were measured on two pipe spools in as-welded condition and two pipe spools after local and furnace PWHT. Measurements were conducted through the thickness in the weld material and adjacent parent metal starting from the weld toes. Besides, three line-scans along pipe length were made 3 mm below outer surface, at pipe wall midthickness, and 3 mm above the inner surface. PWHT was carried out for stress relief; one pipe was conventionally heat treated entirely in an enclosed furnace, and the other was locally heated by a flexible ceramic heating pad. Residual stresses measured after PWHT were at exactly the same locations as those in as-welded condition. Residual stress states of the pipe spools in as-welded condition and after PWHT were compared, and the results were presented in full stress maps. Additionally, through-thickness residual stress profiles and the results of one line scan (3 mm below outer surface) were compared with the respective residual stress profiles advised in British Standard BS 7910 “Guide to methods for assessing the acceptability of flaws in metallic structures” and the UK nuclear industry's R6 procedure. The residual stress profiles in as-welded condition were similar. With the given parameters, local PWHT has effectively reduced residual stresses in the pipe spool to such a level that it prompted the thought that local PWHT can be considered a substitute for global PWHT.

Design Optimisation of a Ferritic Ring Weld Specimen Using FE Modelling

2009 ◽  
Author(s):  
Christopher M. Gill ◽  
Paul Hurrell ◽  
John Francis ◽  
Mark Turski
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Finite Element ◽  
Neutron Diffraction ◽  
Stress Field ◽  
Finite Element Modelling ◽  
Post Weld Heat Treatment ◽  
Stress Fields ◽  
Element Modelling ◽  
Weld Heat

This paper describes the design optimisation of an SA508 ferritic steel ring weld specimen using FE modelling techniques. The aim was to experimentally and analytically study the effect of post weld heat treatment upon a triaxial residual stress field. Welding highly constrained geometries, such as those found in some pressure vessel joints, can lead to the formation of highly triaxial stress fields. It is thought that application of post weld heat treatments will not fully relax hydrostatic stress fields. Therefore a ferritic multi-pass ring weld specimen was designed and optimised, using 2D finite element modelling, to generate a high magnitude triaxial stress field. The specimen thickness and weld-prep geometry was optimised to produce a large hydrostatic stress field and still allow efficient use of neutron diffraction to measure the residual stress. This paper reports the development of the test specimen geometry and compares the results of welding FE analysis and neutron diffraction measurements. Welding residual stresses were experimentally determined using neutron diffraction; both before post weld heat treatment. Three dimensional moving heat source weld finite element modelling has been used to predict the residual stresses generated by the welding process used. Finite element modelling examined the effect of phase transformation upon the residual stress field produced by welding. The relaxation of welding stresses by creep during post weld heat treatment has also been modelled. Comparisons between the modelled and measured as-welded residual stress profiles are presented. This work allows discussion of the effect of post weld heat treatment of triaxial stress fields and determines if finite element modelling is capable of correctly predicting the stress relaxation.

scholarly journals Pengaruh Waktu Penahanan pada Perlakuan Panas Paska Pengelasan terhadap Ketangguhan Sambungan Las Baja

2019 ◽  
Vol 13 (2) ◽  
pp. 80
Author(s):  
Muhamad Fitri ◽  
Bambang Sukiyono ◽  
Martua Limido Simanjuntak
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Local Heating ◽  
Post Weld Heat Treatment ◽  
Impact Testing ◽  
Holding Time ◽  
Aisi 4130 ◽  
The Impact ◽  
Holding Temperature ◽  
Weld Heat

One of the welding methods that is widely used today because it is easier to operate, more practical in its use, can be used for all welding positions and more efficient is called Shield Metal Arc Welding (SMAW). In this welding, the base metal and filler metal will experience thermal cycles which lead to local heating and cooling processes resulting in residual stress and distortion in the material. This residual stress must be removed because it causes a decrease in the mechanical properties of the material. The most widely used method is the thermal method that is by Post Weld Heat Treatment (PWHT). The success of The post-weld heat treatment in removing residual stresses in PWHT is influenced by the holding time. This study aims to examine the effect of holding time on heat treatment, on the weld toughness of steel. In this study, the type of welding used was SMAW welding, the material used was steel AISI 4130, the electrodes used were LB-7018-1 standard application and AWS classification A5.1 E7018-1. The test holding temperature is 650oC. The holding time of testing uses three variables, namely: 2.5 hours, 4.5 hours, 6.5 hours. The Impact testing is done by the Charpy method. From this study, the influence of holding time variation on PWHT holding temperature on the weld strength of AISI 4130 steel was obtained.

scholarly journals The Influence of the Post-Weld Heat Treatment on the Microstructure of Inconel 625/Carbon Steel Bimetal Joint Obtained by Explosive Welding

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 246 ◽  
Author(s):  
Robert Kosturek ◽  
Marcin Wachowski ◽  
Lucjan Śnieżek ◽  
Michał Gloc
Keyword(s):  
Heat Treatment ◽  
Diffusion Zone ◽  
Explosive Welding ◽  
Stress Relief ◽  
Scanning Transmission Electron Microscope ◽  
Post Weld Heat Treatment ◽  
Inconel 625 ◽  
Scanning Transmission ◽  
Inconel 625 Alloy ◽  
Weld Heat

Inconel 625 and steel P355NH were bonded by explosive welding in this study. Explosively welded bimetal clad-plate was subjected to the two separated post-weld heat treatment processes: stress relief annealing (at 620 °C for 90 min) and normalizing (at 910 °C for 30 min). Effect of heat treatments on the microstructure of the joint has been evaluated using light and scanning electron microscopy, EDS analysis techniques, and microhardness tests, respectively. It has been stated that stress relief annealing leads to partial recrystallization of steel P355NH microstructure in the joint zone. At the same time, normalizing caused not only the recrystallization of both materials, but also the formation of a diffusion zone and precipitates in Inconel 625. The precipitates in Inconel 625 have been identified as two types of carbides: chromium-rich M23C6 and molybdenum-rich M6C. It has been reported that diffusion of alloying elements into steel P355NH takes place along grain boundaries with additional formation of voids. Scanning transmission electron microscope observation of the grain microstructure in the diffusion zone shows that this area consists of equiaxed grains (at the side of Inconel 625 alloy) and columnar grains (at the side of steel P355NH).

A Study on Weld Residual Stress Relaxation by Local Post Weld Heat Treatment for Circumferential Weld

2014 ◽  
Author(s):  
Seung-gun Lee ◽  
Youngho Son
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Nuclear Power ◽  
Post Weld Heat Treatment ◽  
Element Analysis ◽  
Minimum Width ◽  
Weld Residual Stress ◽  
The Status ◽  
Baseline Information ◽  
Weld Heat

Weld residual stress is a troublesome problem in nuclear power plant, because it can accelerate crack growth in weld region. For low alloy steel, Post Weld Heat Treatment (PWHT) is essentially needed to relieve residual stress and to temper the hard regions in the heat affected zone (HAZ). Local PWHT is used when it is impractical to heat the whole component in a furnace. The rules and practices of related codes and standards, such as ASME and AWS, associated with local PWHT are quite different. For example, according to ASME Section III, the minimum width of heated band at each side of the weld shall be the thickness of the weld or 2 in., whichever is less. While, according to ASME B31.1, the width of heated band shall be at least three times the wall thickness at the weld of the thickest part being joined. In this paper, the status of the related code and standard associated with local PWHT is briefly summarized, and baseline information on local PWHT is explained based on FEA (Finite Element Analysis) results and optimized local PWHT parameter is suggested to support current code of practices.

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