The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
P J Withers - One of the best experts on this subject based on the ideXlab platform.
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residual stress control of multipass welds using low Transformation Temperature fillers
Materials Science and Technology, 2018Co-Authors: R J Moat, A A Shirzadi, A F Mark, H K D H Bhadeshia, P J WithersAbstract:Low Transformation Temperature (LTT) weld fillers can be used to replace tensile weld residual stresses with compressive ones and reduce the distortion of single-pass welds in austenitic plates. By contrast, weld fillers in multipass welds experience a number of thermal excursions, meaning that the benefit of the smart LTT fillers may not be realised. Here, neutron diffraction and the contour method are used to measure the residual stress in an eight pass groove weld of a 304 L stainless steel plate using the experimental LTT filler Camalloy 4. Our measurements show that the stress mitigating the effect of Camalloy 4 is indeed diminished during multipass welding. We propose a carefully selected elevated interpass hold Temperature and demonstrate that this restores the LTT capability to successfully mitigate residual tensile stresses.
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the effects of filler metal Transformation Temperature on residual stresses in a high strength steel weld
ASME Pressure Vessels and Piping Conference, 2009Co-Authors: J A Francis, H K D H Bhadeshia, P J Withers, H J Stone, Saurabh Kundu, R B Rogge, Leif KarlssonAbstract:Residual stress in the vicinity of a weld can have a large influence on structural integrity. Here the extent to which the martensite-start Temperature of the weld filler metal can be adjusted to engineer the residual stress distribution in a bainitic-martensitic steel weld was investigated. Three single-pass groove welds were deposited by manual-metal-arc welding on 12 mm thick steel plates using filler metals designed to have different martensite-start Temperatures. Their longitudinal, transverse, and normal residual stress distributions were then characterized across the weld cross section by neutron diffraction. It was found that tensile stresses along the welding direction can be reduced or even replaced with compressive stresses if the Transformation Temperature is lowered sufficiently. The results are interpreted in the context of designing better welding consumables.
T I Ramjaun - One of the best experts on this subject based on the ideXlab platform.
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surface residual stresses in multipass welds produced using low Transformation Temperature filler alloys
Science and Technology of Welding and Joining, 2014Co-Authors: T I Ramjaun, R J Moat, H J Stone, Leif Karlsson, M Gharghouri, Kamellia Dalaei, H K D H BhadeshiaAbstract:Tensile residual stresses at the surface of welded components are known to compromise fatigue resistance through the accelerated initiation of microcracks, especially at the weld toe. Inducement of compression in these regions is a common technique employed to enhance fatigue performance. Transformation plasticity has been established as a viable method to generate such compressive residual stresses in steel welds and exploits the phase Transformation in welding filler alloys that transform at low Temperature to compensate for accumulated thermal contraction strains. Neutron and X-ray diffraction have been used to determine the stress profiles that exist across the surface of plates welded with low Transformation Temperature welding alloys, with a particular focus on the stress at the weld toe. For the first time, near surface neutron diffraction data have shown the extent of local stress variation at the critical, fusion boundary location. Compression was evident for the three measurement orientations at the fusion boundaries. Compressive longitudinal residual stresses and tensile transverse stresses were measured in the weld metal.
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review low Transformation Temperature weld filler for tensile residual stress reduction
Materials & Design, 2014Co-Authors: J E Garnham, T I RamjaunAbstract:An attractive, alternative approach for the reduction of harmful residual stresses in weld zones is reviewed, which utilises low Temperature, solid-state, displacive phase Transformations in steel. The theory, latest concepts and practice for the design of such low Transformation Temperature (LTT) filler alloys are considered. By engineering the phase Transformation Temperature of the weld metal so as to take advantage of Transformation expansion, the residual stress state within the weld zone can be significantly altered, most particularly where the weld thermally contracts with any movement of base parts constrained. To date, the technique has been shown to increase fatigue strength for some common weld geometries, which may enable engineering design codes to be favourably re-drafted where such LTT filler alloys are used.
H K D H Bhadeshia - One of the best experts on this subject based on the ideXlab platform.
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residual stress control of multipass welds using low Transformation Temperature fillers
Materials Science and Technology, 2018Co-Authors: R J Moat, A A Shirzadi, A F Mark, H K D H Bhadeshia, P J WithersAbstract:Low Transformation Temperature (LTT) weld fillers can be used to replace tensile weld residual stresses with compressive ones and reduce the distortion of single-pass welds in austenitic plates. By contrast, weld fillers in multipass welds experience a number of thermal excursions, meaning that the benefit of the smart LTT fillers may not be realised. Here, neutron diffraction and the contour method are used to measure the residual stress in an eight pass groove weld of a 304 L stainless steel plate using the experimental LTT filler Camalloy 4. Our measurements show that the stress mitigating the effect of Camalloy 4 is indeed diminished during multipass welding. We propose a carefully selected elevated interpass hold Temperature and demonstrate that this restores the LTT capability to successfully mitigate residual tensile stresses.
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surface residual stresses in multipass welds produced using low Transformation Temperature filler alloys
Science and Technology of Welding and Joining, 2014Co-Authors: T I Ramjaun, R J Moat, H J Stone, Leif Karlsson, M Gharghouri, Kamellia Dalaei, H K D H BhadeshiaAbstract:Tensile residual stresses at the surface of welded components are known to compromise fatigue resistance through the accelerated initiation of microcracks, especially at the weld toe. Inducement of compression in these regions is a common technique employed to enhance fatigue performance. Transformation plasticity has been established as a viable method to generate such compressive residual stresses in steel welds and exploits the phase Transformation in welding filler alloys that transform at low Temperature to compensate for accumulated thermal contraction strains. Neutron and X-ray diffraction have been used to determine the stress profiles that exist across the surface of plates welded with low Transformation Temperature welding alloys, with a particular focus on the stress at the weld toe. For the first time, near surface neutron diffraction data have shown the extent of local stress variation at the critical, fusion boundary location. Compression was evident for the three measurement orientations at the fusion boundaries. Compressive longitudinal residual stresses and tensile transverse stresses were measured in the weld metal.
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the effects of filler metal Transformation Temperature on residual stresses in a high strength steel weld
ASME Pressure Vessels and Piping Conference, 2009Co-Authors: J A Francis, H K D H Bhadeshia, P J Withers, H J Stone, Saurabh Kundu, R B Rogge, Leif KarlssonAbstract:Residual stress in the vicinity of a weld can have a large influence on structural integrity. Here the extent to which the martensite-start Temperature of the weld filler metal can be adjusted to engineer the residual stress distribution in a bainitic-martensitic steel weld was investigated. Three single-pass groove welds were deposited by manual-metal-arc welding on 12 mm thick steel plates using filler metals designed to have different martensite-start Temperatures. Their longitudinal, transverse, and normal residual stress distributions were then characterized across the weld cross section by neutron diffraction. It was found that tensile stresses along the welding direction can be reduced or even replaced with compressive stresses if the Transformation Temperature is lowered sufficiently. The results are interpreted in the context of designing better welding consumables.
R J Moat - One of the best experts on this subject based on the ideXlab platform.
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residual stress control of multipass welds using low Transformation Temperature fillers
Materials Science and Technology, 2018Co-Authors: R J Moat, A A Shirzadi, A F Mark, H K D H Bhadeshia, P J WithersAbstract:Low Transformation Temperature (LTT) weld fillers can be used to replace tensile weld residual stresses with compressive ones and reduce the distortion of single-pass welds in austenitic plates. By contrast, weld fillers in multipass welds experience a number of thermal excursions, meaning that the benefit of the smart LTT fillers may not be realised. Here, neutron diffraction and the contour method are used to measure the residual stress in an eight pass groove weld of a 304 L stainless steel plate using the experimental LTT filler Camalloy 4. Our measurements show that the stress mitigating the effect of Camalloy 4 is indeed diminished during multipass welding. We propose a carefully selected elevated interpass hold Temperature and demonstrate that this restores the LTT capability to successfully mitigate residual tensile stresses.
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surface residual stresses in multipass welds produced using low Transformation Temperature filler alloys
Science and Technology of Welding and Joining, 2014Co-Authors: T I Ramjaun, R J Moat, H J Stone, Leif Karlsson, M Gharghouri, Kamellia Dalaei, H K D H BhadeshiaAbstract:Tensile residual stresses at the surface of welded components are known to compromise fatigue resistance through the accelerated initiation of microcracks, especially at the weld toe. Inducement of compression in these regions is a common technique employed to enhance fatigue performance. Transformation plasticity has been established as a viable method to generate such compressive residual stresses in steel welds and exploits the phase Transformation in welding filler alloys that transform at low Temperature to compensate for accumulated thermal contraction strains. Neutron and X-ray diffraction have been used to determine the stress profiles that exist across the surface of plates welded with low Transformation Temperature welding alloys, with a particular focus on the stress at the weld toe. For the first time, near surface neutron diffraction data have shown the extent of local stress variation at the critical, fusion boundary location. Compression was evident for the three measurement orientations at the fusion boundaries. Compressive longitudinal residual stresses and tensile transverse stresses were measured in the weld metal.
Huibin Xu - One of the best experts on this subject based on the ideXlab platform.
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shape memory effect of grain refined ni54mn25ga21 alloy with high Transformation Temperature
Scripta Materialia, 2004Co-Authors: Yan Li, Chengbao Jiang, Huibin XuAbstract:Abstract It is shown that the mechanical and shape memory characteristics of the polycrystalline Ni 54 Mn 25 Ga 21 high Temperature shape memory alloys can be improved by grain refinement. The maximum shape memory strain is 4.2%, and the compressive plasticity is higher than 10%.
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Effect of Ni excess on phase Transformation Temperatures of NiMnGa alloys
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2003Co-Authors: Chengbao Jiang, Feng, Shengkai Gong, Huibin XuAbstract:A systematic substitution of Ni for Mn, Ga, or both Mn and Ga in the non-stoichiometric NiMnGa alloys is performed. The relationship among the composition, structure and martensitic Transformation Temperatures was studied in detail for the Ni excessive NiMnGa alloys. The martensitic Transformation Temperatures almost linearly increase with increasing Ni content in all the three series from lower than 0 °C up to 300 °C. The increases in rate of the martensitic Transformation Temperatures are different for the three cases. It is large for Ga substituted by Ni, slow for Mn and intermediate for both Mn and Ga. The size factor and electronic concentrations are thought to influence the martensitic Transformation Temperature in the NiMnGa alloys. The determined relationship will be significant for designing a suitable NiMnGa alloy with a required martensitic Transformation Temperature for application at a specific Temperature.
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thermal stability of the ni54mn25ga21 heusler alloy with high Temperature Transformation
Scripta Materialia, 2003Co-Authors: Chengbao Jiang, Gen Feng, Huibin XuAbstract:Abstract Ni 54 Mn 25 Ga 21 is studied with martensitic Transformation Temperature higher than 250 °C. 1000 thermal cycles are performed without obvious differences of its microstructure and martensitic Transformation behavior. The single-phase and the well self-accommodated martensitic twins are thought to be attributed to its high stability of the martensitic Transformation.
