Abstract
Flux-cored wire CO₂ gas shielded welding of Q1100E high-strength steel was carried out for different inter-pass temperatures and bevel forms. This work investigated the effectts of inter-pass temperature and bevel form on the microstructure and mechanical properties of welded joints. The results show that the microstructure of welding metal transforms from ferrite and granular bainite to lath martensite and granular bainite as the inter-pass temperature decreases, the heat-affected zone organization, the trend of coarsening of the lath martensite becomes smaller, and the number of granular bainite is relatively small. With the decrease of the bevel angle, the weld organization is still lath martensite + granular bainite, the lath martensite roughening degree decreases, and the number of granular bainite becomes smaller. Furthermore, as the inter-pass temperature decreases, the tensile strength of the joint increases and the impact toughness of the HAZ increases. As the bevel angle decreases, the tensile strength of the joint continues to grow and the impact toughness of the HAZ increases further. The maximum microhardness of the coarse grain zone was obtained when the inter-pass temperature was 30 °C and the bevel was 40°V.

Key words
Q1100E, CO₂ gas shielded welding, inter-pass temperature, beveling form

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