Optimization of Local Post Weld Heat Treatment Parameters for 9%Cr Heat Resistant Steel Welded Pipes

doi:10.3901/JME.2025.20.113

Abstract

Abstract: Local post-weld heat treatment (PWHT) is generally more practical and cost effective in the field fabrication of large-sized 9%Cr heat-resistant steel welded components, such as power plant boilers. The effectiveness of local PWHT is influenced by the axial and radial temperature gradients inherent in the process which result from localized heating and subsequently induce stress and deformation. The optimal process window of local PWHT for 9%Cr heat-resistant steel pipe joints was proposed, ensuring that excessive induced stress and deformation are avoided while maintaining the desired effects of PWHT. The simulation model of temperature field of local PWHT was first established using finite element methods, and the optimization design method for the parameters of local PWHT was proposed based on both the requirement of PHWT for 9%Cr heat resistant steels and the features of the temperature field of local PWHT. Then, the parameters of local PWHT including the heated band width, heating and cooling rates, heating power, etc., for the commonly used specifications of 9%Cr steel pipes in thermal plants are optimal designed based on the simulated results. Finally, the positions of equivalent temperature measurement points were calculated to monitor the temperature changes in the weld metal on pipe's inner wall during PWHT. The research results are considered capable of guide the on-site PWHT construction and ensure the quality of local PWHT.

Key words: 9%Cr heat resistant steel, local post weld heat treatment, finite element method, optimal design

CLC Number:

TG402

HU Lei, DU Jiaqing, WANG Rui, WANG Xue. Optimization of Local Post Weld Heat Treatment Parameters for 9%Cr Heat Resistant Steel Welded Pipes[J]. Journal of Mechanical Engineering, 2025, 61(20): 113-122.

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