The role of Cu and Al addition on the microstructure and fracture characteristics in the simulated coarse-grained heat-affected zone of high-strength low-alloy steels with superior toughness
Restricted accessResearch articleFirst published online October, 2017
The role of Cu and Al addition on the microstructure and fracture characteristics in the simulated coarse-grained heat-affected zone of high-strength low-alloy steels with superior toughness
The effects of Cu and Al addition on the microstructure and fracture in the coarse-grained heat-affected zone (CGHAZ) of high-strength low-alloy steels with superior toughness were studied and compared with the X70 pipeline base steel counterpart. The microstructure in base steel was dominated by a small fraction of acicular ferrite and predominantly bainite. However, acicular ferrite microstructure was obtained in Cu-bearing steel, which nucleated on complex oxide with outer layer of MnS and CuS because of Cu addition. The microstructure in Al-bearing steel consisted of bainite with ultrafine martensite–austenite constituent, which was refined by Al addition. CGHAZ in Cu-bearing and Al-bearing steels had superior impact toughness and ductile fracture, which were attributed to acicular ferrite and ultrafine martensite–austenite constituent, respectively.
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