scholarly journals Neutron Diffraction Measurements for Residual Stresses in AL-6XN Stainless Steel Welded Beams

10.5772/37537 ◽  
2012 ◽  
Author(s):  
Xiaohua Cheng ◽  
Henry J. ◽  
Thomas Gnaeupel-Herold ◽  
Vladimir Luzin ◽  
John W.
Keyword(s):  
Stainless Steel ◽  
Neutron Diffraction ◽  
Residual Stresses

Neutron Diffraction Measurement and Numerical Simulation to Study the Effect of Repair Depth on Residual Stress in 316L Stainless Steel Repair Weld

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Wenchun Jiang ◽  
Yun Luo ◽  
BingYing Wang ◽  
Wanchuck Woo ◽  
S. T. Tu
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
316L Stainless Steel ◽  
Diffraction Measurement ◽  
Transverse Stress ◽  
Longitudinal Stress ◽  
Hardening Model ◽  
Mixed Hardening

Welding is often used to repair the defects in pressure vessels and piping, but residual stresses are generated inevitably and have a great effect on structure integrity. According to the defect size, different repair depth will be carried out, which leads to different stress state. In this paper, the effect of repair depth on residual stress in 316L stainless steel repair weld has been studied by neutron diffraction measurement and finite element modeling (FEM). The results show that the residual stresses in the deep repair are larger than those in shallow repair weld, because the deep repair involves multipass welding and brings a serious work hardening. In the weld metal, the longitudinal stress has exceeded the yield stress, and increases slightly with the increase of repair depth. In contrast to the longitudinal stress, the transverse stress is more sensitive to the repair depth. With the increase of repair depth, the transverse stress increases and even exceeds the yield strength as the repair depth is 45% of the plate thickness. At the bottom surface of the plate and heat affected zone (HAZ), both the longitudinal and transverse stresses increase as the repair depth increases. It also shows that the mixed hardening model gives the best agreement with the measurement, while isotropic and kinematic hardening models cause an overestimation and underestimation, respectively. Therefore, the mixed hardening model is recommended for the prediction of residual stresses.

A Comparison of Measurement and Modelling of Plastically Induced Residual Stresses in a 316H and a Weld 347 Stainless Steel

2007 ◽  
Author(s):  
M. Turski ◽  
R. C. Wimpory ◽  
N. P. O’Dowd ◽  
P. J. Withers ◽  
K. N. Nikbin
Keyword(s):  
Stainless Steel ◽  
Elevated Temperature ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Notch Root ◽  
Creep Behaviour ◽  
Parent Material ◽  
Operating Conditions ◽  
Residual Stress Field ◽  
Creep Ductility

Neutron diffraction measurements on two types of stainless steel have been carried out on Compact Tension (CT) specimens containing plastically induced residual stresses at the blunt notch root. The materials were a type 316H stainless steel parent material and a type 347 stainless steel weld material. The former exhibited a high creep ductility of ∼25% and the latter exhibited brittle behaviour under operating conditions with less than 10% creep ductility. The work is based in part on an ongoing collaborative effort by the Versailles Agreement on Materials and Standards, Technical Working Area, VAMAS TWA 31 Committee working on ‘Crack Growth of Components Containing Residual Stresses’. The objective of this paper is to examine how residual stresses and/or prior straining and subsequent relaxation at high temperature (550 °C for 316H and 650 °C for 347 weld) contribute to creep crack initiation and growth in the two steels. Elastic/plastic/creep finite-element results and neutron diffraction measurements are presented for the CT specimens before and after elevated temperature exposure. The results suggest that the mechanical induced normalised stresses and strains profiles ahead of the crack tip are insensitive to material, however the relaxation response of the materials appear to be dependent on the creep behaviour and ductility. Localised cracking in the plastically deformed material has been observed in both materials due to the redistribution of the residual stress field and associated creep deformation at elevated temperature.

scholarly journals Evaluation of Residual Stress Relaxation in a Rolled Joint by Neutron Diffraction

2018 ◽  
Vol 2 (4) ◽  
pp. 21 ◽  
Author(s):  
Makoto Hayashi ◽  
John Root ◽  
Ronald Rogge ◽  
Pingguang Xu
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Tensile Deformation ◽  
Pressure Tube ◽  
Thermal Reactor ◽  
Elastic Model ◽  
Heat Treated ◽  
Hoop Stresses

The rolled joint of a pressure tube, consisting of three axial symmetric parts, modified SUS403 stainless steel as an inner extension, Zr–2.5Nb as the pressure tube and an Inconel-718 outer sleeve has been examined by neutron diffraction for residual stresses. It was heat treated to 350 °C for 30, 130 and 635 h to simulate thermal aging over the lifetime of an advanced thermal reactor respectively for 1, 5 and 30 years at an operating temperature of 288 °C. The crystallographic texture has been investigated from cylindric disks cut from the heat treated Zr–2.5Nb pressure tube to determine the proper sample-orientation-dependent hkl reflections for reliable residual strain measurements. Corresponding in situ tensile deformation was carried out to obtain the necessary diffraction elastic constants for the residual stress evaluation. Three-dimensional crystal lattice strains at various locations in the rolled joint before and after the aging treatments for various times were non-destructively measured by neutron diffraction and the residual stress distribution in the rolled joint was evaluated by using the Kröner elastic model and the generalized Hooke’s law. In the crimp region of the rolled joint, it was found that the aging treatment had a much weaker effect on the residual stresses in the Inconel outer sleeve and the modified SUS403 stainless steel extension. In the non-aged Zr–2.5Nb pressure tube, the highest residual stresses were found near its interface with the modified SUS430 stainless steel extension. In the crimp region of the Zr–2.5Nb pressure tube near its interface with the modified SUS430 stainless steel, the average compressive axial stress was −440 MPa, having no evident change during the long-time aging. In the Zr–2.5Nb pressure tube outside closest to the crimp region, the tensile axial and hoop stresses were relieved during the 30 h of aging. The hoop stresses in the crimp region evolved from an average tensile stress of 80 MPa to an average compressive stress of 230 MPa after the 635 h of aging, suggesting that the rolled joint had a good long-term sealing ability against leakage of high temperature water. In the Zr–2.5Nb pressure tube close to the reactor core and far away from the modified SUS403 stainless steel extension, the residual stresses near the inside surface of the pressure tube were almost zero, helping to keep a good neutron irradiation resistance.

Neutron Diffraction Investigation of Residual Stresses Induced in Niobium-Steel Bilayer Pipe Manufactured by Explosive Welding

2013 ◽  
Vol 768-769 ◽  
pp. 697-704 ◽  
Author(s):  
Yury Taran ◽  
Anatoly M. Balagurov ◽  
Basar Sabirov ◽  
Vadim Davydov ◽  
Andrew M. Venter
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Transition Element ◽  
Sudden Increase ◽  
Cross Sectional ◽  
Charged Beam ◽  
Joint Section ◽  
New Generation

Recently, reliable and hermetic joining of stainless steel to niobium pipes has been achieved with the explosive bonding technique. Joining of these two materials are essential to ensure production of a bimetallic transition element of pipe-type for its further use as a part of charged beam acceleration systems of the new generation. A non-destructive neutron diffraction investigation of the tri-axial strains along a radial cross-sectional line through the joint section has been performed. Residual stress results indicate inherently different natures in the residual stress values within the respective pipe sections. In the external stainless steel pipe the residual stresses are tensile, showing a sudden increase to 600 MPa as the interface is approached, whilst being compressive in the internal niobium pipe, not exceeding 650 MPa. A characteristic abrupt stress discontinuity exits at the interface region.

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