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Abstract:
There are
two main purposes should be considered at the same time during postweld
heat treatment (PWHT). One is to relieve the residual stresses, and the
other is to improve the properties of the welding joint. Local PWHT is
usually performed when it is impractical to heat treat the whole vessel
in a furnace. However up to now the assessing criteria in local PWHT are
still very different from one code to another. In this study, the
numerical method such as thermal-visco-elastic-plastic FEM is used and
compared with the experiments. The pipe with original welding residual
stresses is analyzed under different conditions of PWHT especially for
determination of the heated width. Based on above investigations two
criteria are proposed for assessing the effectiveness of local PWHT. One
is the residual stress criterion which is related with the relaxation of
residual stresses, the other is the criterion of temperature different
in soak band which is more related to the improvement of the properties.
Both of criteria should be satisfied during local PWHT.
Key words:
Postweld
heat treatment Residual stress Assessing criterion
Finite element method
CLC No: TG404
国家自然科学基金资助项目. Received 20000604,
received in revised form 20010130
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