Effect of phase transformations on residual stresses in laser welding 09G2 steel

2003 ◽  
Vol 17 (8) ◽  
pp. 645-649 ◽  
Author(s):  
V A Karkhin ◽  
V A Lopota ◽  
N O Pavlova
Keyword(s):  
Residual Stresses ◽  
Laser Welding ◽  
Phase Transformations

Influence of Phase Transformations on Residual Stresses in Welded Structures

2013 ◽  
Author(s):  
R. J. Dennis ◽  
R. Kulka ◽  
O. Muransky ◽  
M. C. Smith
Keyword(s):  
Phase Transformation ◽  
Residual Stresses ◽  
Phase Transformations ◽  
Numerical Models ◽  
Material Model ◽  
Transformation Model ◽  
Austenitic Steels ◽  
Beam Specimen ◽  
Welded Structures ◽  
The Impact

A key aspect of any numerical simulation to predict welding induced residual stresses is the development and application of an appropriate material model. Often significant effort is expended characterising the thermal, physical and hardening properties including complex phenomena such as high temperature annealing. Consideration of these aspects is sufficient to produce a realistic prediction for austenitic steels, however ferritic steels are susceptible to solid state phase transformations when heated to high temperatures. On cooling a reverse transformation occurs, with an associated volume change at the isothermal transformation temperature. Although numerical models exist (e.g. Leblond) to predict the evolution of the metallurgical phases, accounting for volumetric changes, it remains a matter of debate as to the magnitude of the impact of phase transformations on residual stresses. Often phase transformations are neglected entirely. In this work a simple phase transformation model is applied to a range of welded structures with the specific aim of assessing the impact, or otherwise, of phase transformations on the magnitude and distribution of predicted residual stresses. The welded structures considered account for a range of geometries from a simple ferritic beam specimen to a thick section multi-pass weld. The outcome of this work is an improved understanding of the role of phase transformation on residual stresses and an appreciation of the circumstances in which it should be considered.

In Situ Observation of Phase Transformations during Welding of Low Transformation Temperature Filler Material

2010 ◽  
Vol 638-642 ◽  
pp. 3769-3774 ◽  
Author(s):  
Arne Kromm ◽  
Thomas Kannengiesser ◽  
Jens Gibmeier
Keyword(s):  
Residual Stresses ◽  
Phase Transformations ◽  
Volume Change ◽  
Transformation Temperature ◽  
High Energy ◽  
Filler Materials ◽  
Transformation Temperatures ◽  
Welding Processes ◽  
Compressive Residual Stresses

Tensile residual stresses introduced by conventional welding processes diminish the crack resistance and the fatigue lifetime of welded components. In order to generate beneficial compressive residual stresses at the surface of a welded component, various post-weld treatment procedures are available, like shot peening, hammering, etc. These post-weld treatments are, however time and cost extensive. An attractive alternative is to generate compressive stresses over the complete weld joint in the course of the welding procedure by means of so-called Low Transformation Temperature (LTT) filler materials. The volume change induced by the transformation affects the residual stresses in the weld and its vicinity. LTT fillers exhibit a relatively low transformation temperature and a positive volume change, resulting in compressive residual stresses in the weld area. In-situ measurements of diffraction profiles during real welding experiments using Gas Tungsten Arc (GTA)-welding process were realized successfully for the first time. Transformation temperatures during heating and subsequent cooling of LTT welding material could be assessed by means of energy dispersive diffraction using high energy synchrotron radiation. The results show that the temperature of martensite start (Ms) is strongly dependent on the content of alloying elements. In addition the results indicate that different phase transformation temperatures are present depending on the welding depth. Additional determination of residual stresses allowed it to pull together time and temperature resolved phase transformations and the resulting phase specific residual stresses. It was shown, that for the evaluation of the residual stress state of LTT welds the coexisting martensitic and austenitic phases have to be taken into account when describing the global stress condition of the respective material in detail.

Formation of residual stresses during quenching of Ti17 and Ti–6Al–4V alloys: Influence of phase transformations

2021 ◽  
pp. 142456
Author(s):  
J. Teixeira ◽  
D. Maréchal ◽  
R.C. Wimpory ◽  
S. Denis ◽  
F. Lefebvre ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Phase Transformations

Hybrid-laser welding-induced distortions and residual stresses analysis of large-scale stiffener panel

2022 ◽  
Vol 245 ◽  
pp. 110411
Author(s):  
M. Hashemzadeh ◽  
Y. Garbatov ◽  
C. Guedes Soares
Keyword(s):  
Residual Stresses ◽  
Laser Welding ◽  
Large Scale

scholarly journals Influence of Beam Speed on Residual Stresses in the Vicinity of Laser Welds

2014 ◽  
Vol 996 ◽  
pp. 463-468
Author(s):  
Nikolaj Ganev ◽  
Kamil Kolařík ◽  
Zdenek Pala ◽  
Stanislav Němeček ◽  
Jiří Čapek
Keyword(s):  
Residual Stresses ◽  
Laser Beam ◽  
Laser Welding ◽  
Grain Sizes ◽  
Laser Welds ◽  
Contribution Mapping ◽  
Compressive Residual Stresses

One of the drawbacks of the laser welding is distortion of the welded bodies that is closely linked with the generation and redistribution of residual stresses in the vicinity of the weld. In this contribution, mapping of surface macroscopic residual stresses and grain sizes was performed for several welds created with the laser beam with various speeds. Larger distortions are exhibited by samples manufactured with higher laser beam speed, which also exhibit substantial compressive residual stresses perpendicularly to the welds axis.

scholarly journals Modeling Solid-State Phase Transformations of 13Cr-4Ni Steels in Welding Heat-Affected Zone

2019 ◽  
Vol 51 (3) ◽  
pp. 1208-1220
Author(s):  
J. B. Lévesque ◽  
J. Lanteigne ◽  
H. Champliaud ◽  
D. Paquet
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
Solid State ◽  
Martensitic Transformation ◽  
Residual Stresses ◽  
Phase Transformations ◽  
Heat Affected Zone ◽  
Martensitic Stainless Steel ◽  
Fatigue Crack Initiation ◽  
Hydraulic Turbine

AbstractFatigue damage is commonly encountered by operators of Francis type hydraulic turbine runners made of 13Cr-4Ni soft martensitic stainless steel. These large and complex welded casting assemblies are subjected to fatigue crack initiation and growth in the vicinity of their welded regions. It is well known that fatigue behavior is influenced by residual stresses and the microstructure. By including solid-state phase transformation models in welding simulations, phase distribution can be evaluated along with their respective volumetric change and their effect on residual stresses. Thus, it enables the assessment of welding process on fatigue crack behavior by numerical methods. This paper focuses on modeling solid-state phase transformations of 13Cr-4Ni soft martensitic stainless steel, used for manufacturing hydraulic turbine runners, occurring upon welding. It proposes to determine the material parameters of the models for both the austenitic and the martensitic transformation by nonisothermal dilatometry tests. The experiments are conducted in a quenching dilatometer with applied thermal conditions as experienced in the heat-affected zone of homogeneous welds. The activation energy and the kinetic parameters of the austenitic transformation from fully martensitic state are measured from the experimental results. The martensitic transformation modeling from a fully austenitic domain is also presented.

Numerical Investigation of the Influence of Microstructure on the Residual Stress Distribution and Distortion in DP600 Welds

2011 ◽  
Vol 681 ◽  
pp. 79-84 ◽  
Author(s):  
A.M.Akbari Pazooki ◽  
M.J.M. Hermans ◽  
I.M. Richardson
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Phase Transformations ◽  
Dual Phase Steel ◽  
Ferrite Matrix ◽  
Volume Changes ◽  
Heating And Cooling ◽  
Distortion Level ◽  
Martensitic Phase Transformations ◽  
Cct Diagrams

Dual phase steel consists of martensite embedded in a ferrite matrix. The material experiences high heating and cooling rates during welding, which alter the microstructure significantly. In this work the effects of solid state phase transformations on the prediction of residual stresses and distortion during welding of DP600 steel is investigated. Phase fractions have been calculated implicitly using continuous cooling time (CCT) diagrams. The results of the model are compared with experimental measurements for bead-on-plate welds made on DP600 sheets. It is found that the volume changes and the increase of the strength due to the martensitic transformation have both a significant effect on the residual stress and distortion level although in opposite directions. Martensitic phase transformations in DP600 steel tend to reduce tensile residual stresses in the weld metal.

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