Post weld heat treatment of bisalloy 80 steel: Mechanics and industry safety code compatibility

Houman Alipooramirabad; Anna Paradowska; Mark Reid; Reza Ghomashchi

doi:10.1016/j.ijpvp.2025.105434

Post weld heat treatment of bisalloy 80 steel: Mechanics and industry safety code compatibility

Houman Alipooramirabad (Corresponding / Lead Author), Anna Paradowska, Mark Reid, Reza Ghomashchi

Research output: Contribution to journal › Article › peer-review

Abstract

The present study utilized both in-situ and ex-situ neutron diffraction to evaluate the evolution of residual strains/stresses before, during and after Post-Weld Heat Treatment (PWHT) of quenched and tempered (Q&T) Bisalloy 80 steel welded by pulsed Gas Metal Arc Welding (GMAW-P). It was found that strain/stress relaxation mainly occurred during the reheating step with a high relaxation rate and steep slope (∼67 % of strain relaxation) while linear strain relief was observed during holding (soaking) time. Most of the strain relief occurred within the temperature range of 450°C–600 °C which is believed to be due to creep strain development occurring far earlier than the component reaching the isothermal holding temperature. The ex-situ neutron diffraction measurements were similar to in-situ results confirming the applied PWHT effectively mitigated the residual stresses (the maximum longitudinal stress reduced to around 23 % of the weld metal yield strength).

The measurements were compared with existing literature data and the current fitness of safety assessment codes (BS7910 and R6). It was found that both assessment codes were conservative for both the transverse and longitudinal residual stresses in the region close to the weld toe. Furthermore, both standards may underestimate through-thickness residual stresses in the transverse direction.

Original language	English
Journal	International Journal of Pressure Vessels and Piping
Volume	214
DOIs	https://doi.org/10.1016/j.ijpvp.2025.105434
Publication status	Published (VoR) - 7 Jan 2025

Funding

This research was supported by the Australian Nuclear Science and Technology (ANSTO) under the facilities access award P7087.

Funders	Funder number
Not added	P7087

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title = "Post weld heat treatment of bisalloy 80 steel: Mechanics and industry safety code compatibility",

abstract = "The present study utilized both in-situ and ex-situ neutron diffraction to evaluate the evolution of residual strains/stresses before, during and after Post-Weld Heat Treatment (PWHT) of quenched and tempered (Q&T) Bisalloy 80 steel welded by pulsed Gas Metal Arc Welding (GMAW-P). It was found that strain/stress relaxation mainly occurred during the reheating step with a high relaxation rate and steep slope (∼67 % of strain relaxation) while linear strain relief was observed during holding (soaking) time. Most of the strain relief occurred within the temperature range of 450°C–600 °C which is believed to be due to creep strain development occurring far earlier than the component reaching the isothermal holding temperature. The ex-situ neutron diffraction measurements were similar to in-situ results confirming the applied PWHT effectively mitigated the residual stresses (the maximum longitudinal stress reduced to around 23 % of the weld metal yield strength).The measurements were compared with existing literature data and the current fitness of safety assessment codes (BS7910 and R6). It was found that both assessment codes were conservative for both the transverse and longitudinal residual stresses in the region close to the weld toe. Furthermore, both standards may underestimate through-thickness residual stresses in the transverse direction.",

author = "Houman Alipooramirabad and Anna Paradowska and Mark Reid and Reza Ghomashchi",

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doi = "10.1016/j.ijpvp.2025.105434",

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journal = "International Journal of Pressure Vessels and Piping",

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T1 - Post weld heat treatment of bisalloy 80 steel

T2 - Mechanics and industry safety code compatibility

AU - Alipooramirabad, Houman

AU - Paradowska, Anna

AU - Reid, Mark

AU - Ghomashchi, Reza

PY - 2025/1/7

Y1 - 2025/1/7

N2 - The present study utilized both in-situ and ex-situ neutron diffraction to evaluate the evolution of residual strains/stresses before, during and after Post-Weld Heat Treatment (PWHT) of quenched and tempered (Q&T) Bisalloy 80 steel welded by pulsed Gas Metal Arc Welding (GMAW-P). It was found that strain/stress relaxation mainly occurred during the reheating step with a high relaxation rate and steep slope (∼67 % of strain relaxation) while linear strain relief was observed during holding (soaking) time. Most of the strain relief occurred within the temperature range of 450°C–600 °C which is believed to be due to creep strain development occurring far earlier than the component reaching the isothermal holding temperature. The ex-situ neutron diffraction measurements were similar to in-situ results confirming the applied PWHT effectively mitigated the residual stresses (the maximum longitudinal stress reduced to around 23 % of the weld metal yield strength).The measurements were compared with existing literature data and the current fitness of safety assessment codes (BS7910 and R6). It was found that both assessment codes were conservative for both the transverse and longitudinal residual stresses in the region close to the weld toe. Furthermore, both standards may underestimate through-thickness residual stresses in the transverse direction.

AB - The present study utilized both in-situ and ex-situ neutron diffraction to evaluate the evolution of residual strains/stresses before, during and after Post-Weld Heat Treatment (PWHT) of quenched and tempered (Q&T) Bisalloy 80 steel welded by pulsed Gas Metal Arc Welding (GMAW-P). It was found that strain/stress relaxation mainly occurred during the reheating step with a high relaxation rate and steep slope (∼67 % of strain relaxation) while linear strain relief was observed during holding (soaking) time. Most of the strain relief occurred within the temperature range of 450°C–600 °C which is believed to be due to creep strain development occurring far earlier than the component reaching the isothermal holding temperature. The ex-situ neutron diffraction measurements were similar to in-situ results confirming the applied PWHT effectively mitigated the residual stresses (the maximum longitudinal stress reduced to around 23 % of the weld metal yield strength).The measurements were compared with existing literature data and the current fitness of safety assessment codes (BS7910 and R6). It was found that both assessment codes were conservative for both the transverse and longitudinal residual stresses in the region close to the weld toe. Furthermore, both standards may underestimate through-thickness residual stresses in the transverse direction.

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U2 - 10.1016/j.ijpvp.2025.105434

DO - 10.1016/j.ijpvp.2025.105434

M3 - Article

VL - 214

JO - International Journal of Pressure Vessels and Piping

JF - International Journal of Pressure Vessels and Piping

ER -

Post weld heat treatment of bisalloy 80 steel: Mechanics and industry safety code compatibility

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