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Abstract:
The relationship between microstructure and toughness of the welding
heat-affected zone (HAZ) of a pipeline steel is investigated by means of
thermal simulation test and transmission electron microscope (TEM). It
is found that the inter-critically reheated coarse-grained heat-affected
zone (IRCGHAZ) of experimental steel has the lowest toughness when the
second peak temperature is at (α+γ) region during multi-pass welding.
This local embrittlement is mainly attributed to the morphology, amount
and size of M-A constituent. It is also found that the microstructure
inhabitance at IRCGAHZAZ has a deleterious effect on the toughness. On
the basis of above experimental results, it is suggested that the local
embrittlement should be prevented by using pre-heating cycle, which
could eliminate the microstructure inhabitance, and using temper-heating
cycle which could improve the morphology, amount and size of M-A
constituent.
Key words:
Pipeline
steel HAZ Embrittlement Prevention
CLC No: TG142.1
中国石油天然气集团公司石油管力学和环境行为重点实验室基金资助项目. Received 20000626,
received in revised form 20000826
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