Thermal, Metallurgical and Mechanical Phenomena in the Heat Affected Zone

Kaplan, D.; Murry, Guy

doi:10.1002/9780470611272.ch3

Cited by 7 publications

(7 citation statements)

References 21 publications

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“…This large value of t 8/5 is a distinctive feature of TLPB compared with AW. Typical values of t 8/5 for AW range from a few seconds for gas tungsten arc welding to less than a minute for submerged arc welding [8].…”

Section: Residual Stress State Analysis At the Core Of The Weldmentmentioning

confidence: 99%

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Measurement and simulation of residual stresses in transient liquid phase bonded ferritic steels

et al. 2022

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Ferritic steel bars -25 mm in diameterwere welded by transient liquid phase bonding (TLPB) using Fe-based amorphous metallic foils as filler material. The resulting residual stress (RS) field shows a low peak magnitudeof 147 MPaas measured by neutron diffraction.The most distinctive feature of TLPB is the heat input delivered simultaneously at the whole joint that allows much lower cooling rates compared with arc welding (AW).Therefore, the elapsed time between 800 and 500 ºC (t 8/5) was particularly long reaching 390 sec. As a result, a low RS peak magnitude (147 MPa) was obtained in the as-welded condition. This value is well below the RS peak magnitude obtained with AW which typically attain the yield strength of the base metal (276 MPa).The numerical simulation of RS at the welded bars was performed by a thermal and mechanical analysis. It shows that TLPB produced a large austenized region, low cooling rates and a remarkable t 8/5. Consequently, the large volume in which the heat input is delivered is the driving force to reduce RS peak magnitudes. From the mechanical analysis, it was found that the simulated RS were in good agreement with the measured RS. Therefore, the proposed numerical simulation model can be used to predict RS in TLPB weldments.

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Section: Residual Stress State Analysis At the Core Of The Weldmentmentioning

confidence: 99%

“…This thermal cycle at the joint allows the generation of low cooling rates. For ferritic steels, the elapsed time between 800 and 500 ºC (t 8/5)range of temperature in which the austenite transformation takes place, is particularly long [8]. As a result, TLPB has a great potential to develop low RS.…”

Section: Introductionmentioning

confidence: 99%

Measurement and simulation of residual stresses in transient liquid phase bonded ferritic steels

et al. 2022

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“…In the literature, several empirical formulas for the calculation of CE are available. We used the formula adopted by the International Institute of Welding (IIW) 17,18 in 1967. Having defined C, Mn, Cr, Mo, V, Ni, and Cu as the mass percentages of the elements that give hardenability and thus lower weldability (Table 1), the carbon equivalent calculated by IIW is described by Equation ():

CE = C + \frac{Mn}{6} + \frac{Cr + Mo + V}{5} + \frac{Ni + Cu}{15}

Based on that formula, the steel is considered weldable without special precautions if CE <0.41.…”

Section: Analyses Of the Supportmentioning

confidence: 99%

Concurrent design error, poor welding, and code inadequacy cause jet‐FIRE on a topping column

Doglione

Piccinini

2022

Process Safety Progress

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The paper reports the analysis of an accident that occurred in a petroleum refinery.During the start-up maneuver of the topping column, the anchoring of the riser pipe to metal guide support on the topping column suddenly failed. This caused a rip in the riser pipe, and gasoline squirted out, followed by the ignition of a jet fire. The investigations showed an unusual differential thermal expansion between the topping column and riser. The riser guide to the column was wrongly installed, preventing adequate relative displacements when thermal expansion occurred. Metallographic and fractographic analyses did not discover any inadequacy in the steel of the failed parts. But the lack of penetration of the welding seam resulted in a weak bond between the support and the riser. The high stress induced by the badly installed guide and the weakness of the welding was the cause of the failure and the jet fire. The paper also analyses the application of existing codes to the riser support installation and shows that the code recommendations do not satisfactorily cover the case of topping column risers. The issue is raised to alert operators in the plant, stimulate the improvement of the codes and standards, and avoid future accidents.

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“…PWHT is generally applied to the weldment in order to eliminate the welding residual stress and improve the properties of weld joint . In fact, the beneficial effect of PWHT is not primarily due to reduction of residual stress, but is due to desired metallurgical structure by tempering or removal of aging effect . Therefore, in this study, we processed low‐C medium‐Mn high strength plate to investigate the effect of PWHT on microstructure, microhardness, and low temperature impact toughness of gas shield arc weld joint.…”

Section: Introductionmentioning

confidence: 99%

“…[16][17][18] In fact, the beneficial effect of PWHT is not primarily due to reduction of residual stress, but is due to desired metallurgical structure by tempering or removal of aging effect. [16,19] Therefore, in this study, we processed low-C medium-Mn high strength plate to investigate the effect of PWHT on microstructure, microhardness, and low temperature impact toughness of gas shield arc weld joint. Moreover, the toughness mechanism of HAZ is also elucidated.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Impact Toughness of Heat Affected Zone in Gas Shield Arc Weld Joint of Low‐C Medium‐Mn High Strength Steel by Post‐Weld Heat Treatment

et al. 2017

steel research int.

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In the present study, two different post weld heat treatments (PWHT) are carried out on gas shield arc welded low-C medium-Mn high strength steel to explore the effect of PWHT on microstructure, microhardness, and low temperature toughness of heat affected zone (HAZ). The results show that when the weld joint is PWHT at 630 C for 30 min, the microhardness of HAZ is homogeneous and almost identical to base metal (BM). The microstructure of HAZ comprises of tempered martensite and strip-shaped reversed austenite. The impact energy of fusion line (FL), coarse-grained HAZ (CGHAZ), and fine grained HAZ (FGHAZ) at À40 C is enhanced by 29 J (from 42 to 71 J), 42 J (from 68 to 110 J), and 33 J (from 140 to 173 J), respectively, compared to the weld joint, which is PWHT at 200 C for 120 min. The formation of reversed austenite with certain stability in the HAZ is the main toughening mechanism when the weld joint is PWHT at 630 C. Reversed austenite enhances the impact energy significantly through the transformation-induced plasticity (TRIP) effect, which releases the stress concentration, improves the crack initiation energy, and effectively prevents the propagation of cleavage crack.

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Thermal, Metallurgical and Mechanical Phenomena in the Heat Affected Zone

Cited by 7 publications

References 21 publications

Measurement and simulation of residual stresses in transient liquid phase bonded ferritic steels

Measurement and simulation of residual stresses in transient liquid phase bonded ferritic steels

Concurrent design error, poor welding, and code inadequacy cause jet‐FIRE on a topping column

Enhanced Impact Toughness of Heat Affected Zone in Gas Shield Arc Weld Joint of Low‐C Medium‐Mn High Strength Steel by Post‐Weld Heat Treatment

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