scholarly journals An Economical and Mechanical Investigation on Local Post-Weld Heat Treatment for Stiffened Steel Plates in Bridge Structures

2021 ◽  
Vol 2 (4) ◽  
pp. 714-727
Author(s):  
Mikihito Hirohata ◽  
Shuhei Nozawa ◽  
Károly Jármai
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
High Energy ◽  
Post Weld Heat Treatment ◽  
Welding Residual Stress ◽  
Steel Plates ◽  
Bridge Structures ◽  
Long Time ◽  
Mechanical Investigation ◽  
Weld Heat

A heat treatment is effective for reducing the residual stress of the welded structures. A post-weld heat treatment (PWHT) requires a large heating apparatus (furnace). It requires a high energy, a long time, and a high cost. For examining the possibility of cost and energy saving in PWHT work, an economical and mechanical investigation of the local PWHT to stiffened plate members in steel bridges was conducted. The expense of apparatus for the furnace PWHT was 1.5 times higher than that of local PWHT by sheet-type ceramic heaters. When the number of heater units was reduced and were repeatedly used, the expense for the apparatus became lower. However, it took longer to complete the heat treatment than with the furnace PWHT or the local PWHT with full heater units. The thermal elastic-plastic finite element (FE) analysis examined the effect of local PWHT. The tendency of the stress distribution after the local PWHT differed from the welding residual stress or the stress after the furnace PWHT because of the temperature difference between the heated and the non-heated parts of the local PWHT. However, the effect of residual stress relief by the local PWHT could be almost the same as that of the furnace PWHT.

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

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.

Evaluation of Cracking Behavior of SPV50Q High Strength Steel Weldment in Wet H2S Containing Environment

2005 ◽  
Vol 297-300 ◽  
pp. 951-957 ◽  
Author(s):  
Jian Ming Gong ◽  
Jian Qun Tang ◽  
Xian Chen Zhang ◽  
Shan Tung Tu
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
High Strength Steel ◽  
High Strength ◽  
Post Weld Heat Treatment ◽  
Welding Residual Stress ◽  
Cracking Behavior ◽  
Steel Weldment ◽  
Hydrogen Induced Cracking ◽  
Weld Heat

JIS-SPV50Q high strength steel is often employed in construction of liquid petroleum gas (LPG) spherical tanks due to its high strength and good ductility. In general, post weld heat treatment is not performed after welding of SPV50Q high strength steel and welding residual stress will be retained in weldment. Service experience and inspection indicate that higher H2S concentration and welding residual stress result in the environmental failure, such as blistering or hydrogen induced cracking (HIC), sulfide stress corrosion cracking (SSCC) and stress oriented hydrogen induced cracking (SOHIC). In the present paper, the cracking behavior of SPV50Q high strength steel weldment by manual electric arc welding has been investigated in various saturate solutions with different concentrations of H2S. The results of slow strain rate testing, performed at a strain of 1×10-6s-1, reveal the presence of SSCC and HIC in the base metal adjacent to HAZ. The ffects of the different temperatures of post weld heat treatment on cracking are discussed. The suitable post weld heat treatment could increase the resistance of SPV50Q weldment on SSCC or HIC and does not decrease the mechanical properties of SPV50Q weldment.

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.

Numerical Simulation of Local Post Weld Heat Treatment by Electric Heating Method of Pressure Equipment

2017 ◽  
Author(s):  
Liang Sun ◽  
Fang Ji ◽  
Xiaomei Wang ◽  
Guide Deng ◽  
Lei Cheng
Keyword(s):  
Numerical Simulation ◽  
Heat Treatment ◽  
Wall Temperature ◽  
Electric Heating ◽  
Post Weld Heat Treatment ◽  
Welding Residual Stress ◽  
Band Width ◽  
Butt Weld ◽  
Heating Method ◽  
Weld Heat

The local post weld heat treatment by electric heating method is widely used to eliminate welding residual stress in processes of manufacture and maintenance of pressure equipment. The key point of local post weld heat treatment is to choose a reasonable heated band width and insulated band width. But the criterions to determine the minimum heated band width and insulated band width are different according to Chinese, European and American standards, which are GB/T 30583-2014, EN 13445-4: 2009 and AWS D10.10/D10.10M :1999, respectively. Taking the local post weld heat treatment for the circumferential butt weld between two thick cylinders both with a 115 mm thickness as an example, numerical simulation is used to compare the wall temperature distribution of the cylinders during the heat preservation stage when the heated band width and insulated band width are chose according to the above three standards, and the numerical simulation was verified by the tested temperature from one field experiment. The results show that the numerical calculation method can accurately predict the wall temperature of the cylinders during the local heat treatment, and the wall temperature of the surfaces on which the heaters are arranged according to the three standards all well meets the requirement of the heat treatment, but the wall temperature of the surfaces without the heaters cannot meet the temperature requirement. So double-side heating and double-side insulating are suggested to be adopted during local post weld heat treatment.

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.

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