Relaxation mechanism of residual stress inside logs by heat treatment: choosing the heating time and temperature

2003 ◽  
Vol 49 (1) ◽  
pp. 0022-0028 ◽  
Author(s):  
M. Nogi ◽  
H. Yamamoto ◽  
T. Okuyama
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Relaxation Mechanism ◽  
Heating Time

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 Process Signature for Laser Hardening

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 465
Author(s):  
Friedhelm Frerichs ◽  
Yang Lu ◽  
Thomas Lübben ◽  
Tim Radel
Keyword(s):  
Residual Stress ◽  
Phase Transformation ◽  
Heating Time ◽  
Temperature Gradients ◽  
Laser Hardening ◽  
Thermal Loads ◽  
Zero Crossing ◽  
Residual Stress State ◽  
Stress Curve ◽  
Process Signature

During many manufacturing processes for surface treatment of steel components heat will be exchanged between the environment and the workpiece. The heat exchange commonly leads to temperature gradients within the surface near area of the workpiece, which involve mechanical strains inside the material. If the corresponding stresses exceed locally the yield strength of the material residual stresses can remain after the process. If the temperature increase is high enough additionally phase transformation to austenite occurs and may lead further on due to a fast cooling to the very hard phase martensite. This investigation focuses on the correlation between concrete thermal loads such as temperature and temperature gradients and resulting modifications such as changes of the residual stress, the microstructure, and the hardness respectively. Within this consideration the thermal loads are the causes of the modifications and will be called internal material loads. The correlations between the generated internal material loads and the material modifications will be called Process Signature. The idea is that Process Signatures provide the possibility to engineer the workpiece surface layer and its functional properties in a knowledge-based way. This contribution presents some Process Signature components for a thermally dominated process with phase transformation: laser hardening. The target quantities of the modifications are the change of the residual stress state at the surface and the position of the 1st zero-crossing of the residual stress curve. Based on Finite Element simulations the internal thermal loadings during laser hardening are considered. The investigations identify for the considered target quantities the maximal temperature, the maximal temperature gradient, and the heating time as important parameters of the thermal loads.

Heat Treatment Effects on Distortion, Residual Stress, and Retained Austenite in Carburized 4320 Steel

2014 ◽  
Vol 783-786 ◽  
pp. 692-697 ◽  
Author(s):  
Andrew Clark ◽  
Randy J. Bowers ◽  
Derek O. Northwood
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Retained Austenite ◽  
Compressive Residual Stress ◽  
Surface Residual Stress ◽  
Depth Profiles ◽  
Size And Shape ◽  
Austenite Content ◽  
Treatment Conditions ◽  
The Difference

The effects of heat treatment on distortion, residual stress, and retained austenite were compared for case-carburized 4320 steel, in both the austempered and quench-and-tempered condition. Navy C-ring samples were used to quantify both size and shape distortions, as well as residual stress. The austempering heat treatment produced less distortion and a higher surface residual stress. Both hoop and axial stresses were measured; the difference between them was less than seven percent in all cases. Depth profiles were obtained for residual stress and retained austenite from representative C-ring samples for the austempered and quench-and-tempered heat treatment conditions. Austempering maintained a compressive residual stress to greater depths than quench-and-tempering. Quench-and-tempering also resulted in lower retained austenite amounts immediately beneath the surface. However, for both heat treatments, the retained austenite content was approximately one percent at depths greater than 0.5 mm.

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.

Influence of Heat Treatment on Residual Stress Formation in the Wear-Resistant Steel 60–Steel 15–Steel 60 Bimetal Material

2021 ◽  
Vol 12 (1) ◽  
pp. 5-9
Author(s):  
N. N. Sergeev ◽  
A. N. Sergeev ◽  
S. N. Kutepov ◽  
A. E. Gvozdev ◽  
A. G. Kolmakov ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Resistant Steel ◽  
Wear Resistant ◽  
Stress Formation

Finite Element Analysis of the Rolling Contact Fatigue Life of Railcar Wheels

2008 ◽  
Vol 575-578 ◽  
pp. 1461-1466
Author(s):  
Byeong Choon Goo ◽  
Jung Won Seo
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Element Analysis ◽  
Railway Vehicles ◽  
Contact Fatigue Life

Railcar wheels and axles belong to the most critical components in railway vehicles. The service conditions of railway vehicles have been more severe in recent years due to speed-up. Therefore, a more precise evaluation of railcar wheel life and safety has been requested. Wheel/rail contact fatigue and thermal cracks due to braking are two major mechanisms of the railcar wheel failure. One of the main sources influencing on the contact zone failure is residual stress. The residual stress in wheels formed during heat treatment in manufacturing changes in the process of braking. Thus the fatigue life of railcar wheels should be estimated by considering both thermal stress and rolling contact. Also, the effect of residual stress variation due to manufacturing process and braking process should be included in simulating contact fatigue behavior. In this paper, an evaluation procedure for the contact fatigue life of railcar wheels considering the effects of residual stresses due to heat treatment, braking and repeated contact load is proposed. And the cyclic stressstrain history for fatigue analysis is simulated by finite element analysis for the moving contact load.

Flaw Stability Analysis of Semi-Elliptical Surface Cracks in Canisters Under the Influence of Welding Residual Stress

2016 ◽  
Author(s):  
Jinhua Shi ◽  
Liwu Wei ◽  
Poh-Sang Lam
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Spent Nuclear Fuel ◽  
External Surface ◽  
Welding Residual Stress ◽  
Surface Cracks ◽  
Coastal Regions ◽  
Dry Storage ◽  
Induced Stress ◽  
Design Pressure

Many stainless steel canisters for the dry storage of spent nuclear fuel are located in coastal regions. Because the heat treatment for relieving the welding residual stress is not required during fabrication, these canisters may be susceptible to chloride induced stress corrosion cracking due to the deliquescence of chloride-bearing marine salts or dust that enter the overpack system and deposit on the canister external surface. The NDE techniques and the associated delivery system are being developed to conduct periodic inservice inspections. The acceptance standards are needed to disposition findings should flaw-like indications be found. The instability crack lengths and depths for these flaws in the form of semi-elliptical shape near the welds are determined with R6 procedure. The cracks are subject to the canister design pressure and handling loads as well as the estimated welding residual stresses.

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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