Neutron and Synchrotron Diffraction Measurements of Residual Stress in Steel Weldments

2007 ◽  
Author(s):  
Anna M. Paradowska ◽  
John W. H. Price ◽  
Raafat Ibrahim
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Stress Distribution ◽  
State Of The Art ◽  
Mechanical Tests ◽  
Post Weld Heat Treatment ◽  
Synchrotron Diffraction ◽  
Before And After ◽  
Strain Stress ◽  
Weld Heat

This paper explores the use of state-of-the-art instruments such as neutron and synchrotron diffraction for evaluation of residual stress in carbon steel welded components. The study shows significant variation in transverse residual strain/stress distribution across the length of the weld. Measurements before and after post weld heat treatment are reported together with traditional mechanical tests. The changes in residual stress distribution as weld beads are added in multi-bead welds are also presented. Important practical results are: i) The start and end of the weld are the most critical parts of the weldment. Implementations of run-in and run-out (which are subsequently ground off) can minimize the residual stress at the start and end of the weld. ii) Manipulation of the sequence especially around the weld toes can minimize the value of the residual stress in that region. iii) Post weld heat treatment is very effective at reducing residual stresses.

Comparison of Neutron and Synchrotron Diffraction Measurements of Residual Stress in Bead-on-Plate Weldments

2010 ◽  
Vol 132 (1) ◽  
Author(s):  
Anna M. Paradowska ◽  
John W. H. Price ◽  
Trevor R. Finlayson ◽  
Ulrich Lienert ◽  
Raafat Ibrahim
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Residual Strain ◽  
Development Process ◽  
Synchrotron Diffraction ◽  
Stress Relieving ◽  
Before And After ◽  
Strain Stress ◽  
Good Agreement

This paper explores the use of neutron and synchrotron diffractions for the evaluation of residual stresses in welded components. It has been shown that it is possible to achieve very good agreement between the two independent diffraction techniques. This study shows the significance of the weld start and end sites on the residual strain/stress distribution. Quantitative evaluation of the residual stress development process for multibead weldments has been presented. Some measurements were also taken before and after postweld stress relieving to establish the reduction and redistribution of the residual stress. The detailed measurements of residual stress around the weld achieved in this work significantly improve the knowledge and understanding of residual stress in welded components.

The effects of restraint and post-weld heat treatment on residual stress distribution in a bead-on-plate weld

2007 ◽  
Vol 15 (3) ◽  
pp. 231-241 ◽  
Author(s):  
A. M. Paradowska ◽  
J. W. H. Price ◽  
R. Ibrahim ◽  
T. R. Finlayson ◽  
M. I. Ripley ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Stress Distribution ◽  
Post Weld Heat Treatment ◽  
Residual Stress Distribution ◽  
Weld Heat

Relaxation of Exemption Requirement of PWHT for SA-508 Grade 1A, by Consideration Surface Welding Residual Stress As Evaluated by Instrumented Indentation Testing Method

2017 ◽  
Author(s):  
Jong-hyoung Kim ◽  
Jun Sang Lee ◽  
Sungki Choi ◽  
Jong-sung Kim ◽  
Dongil Kwon
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Residual Stress ◽  
Power Plants ◽  
Mechanical Tests ◽  
Pressure Vessels ◽  
Post Weld Heat Treatment ◽  
Welding Residual Stress ◽  
Acceptance Criterion ◽  
Weld Heat

Generally, post-weld heat treatment is applied to decrease welding residual stress and improve the mechanical properties and microstructure of weldment, and its performance has been recommended for many years [1, 2]. However, current steel-making technology has improved significantly and, steel toughness levels have generally improved substantially [1]. Additionally for several quenched and tempered steels, it is reported that in some cases, mechanical properties such as tensile strength and impact toughness are degraded after post-weld heat treatment [3]. In addition, for large steel assemblies, post-weld heat treatment can be expensive, so that there is an economic incentive to avoid post-weld heat treatment [2]. The research presented here suggests a way to exempt post-weld heat treatment for SA-508 Grade 1A material, which is used for pressure vessels in nuclear power plants, by considering both mechanical properties and residual stress to simplify the welding procedure. Weldments made of 120 mm thick SA-508 Grade 1A should be post-weld heat treated, according to current ASME BPV Code. In order to increase the PWHT exemption thickness to 120 mm, we performed mechanical tests using welding coupons without PWHT; the test results satisfied current mechanical property criteria. We present a residual stress acceptance criterion based on brittle fracture criteria in this research.

Residual stress distributions in a P91 steel-pipe girth weld before and after post weld heat treatment

2012 ◽  
Vol 534 ◽  
pp. 663-672 ◽  
Author(s):  
S. Paddea ◽  
J.A. Francis ◽  
A.M. Paradowska ◽  
P.J. Bouchard ◽  
I.A. Shibli
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Post Weld Heat Treatment ◽  
Steel Pipe ◽  
Stress Distributions ◽  
P91 Steel ◽  
Before And After ◽  
Weld Heat

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.

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