Cracking Problem During Room Temperature Cold Rolling of Three High Al Low C Ferritic Low Density-Steels

High Al low C ferritic low-density steels exhibit a remarkable reduction in density, around 8 to 15%, compared to conventional steels. However, in high Al, Fe-Al-Mn-C system, during room temperature cold rolling process, a challenging issue arises in the form of center and edge cracking, which negatively impacts the ductility. This study is aimed to investigate the effects of cold, warm, and hot rolling of three high Al low-carbon low-density steels with 6.8 wt.%, 9.1 wt.%, and 9.7 wt.% Al. The focus is on the resulting microstructural features, including the presence of brittle Fe3Al intermetallic and κ-carbide within the ferrite matrix. During cold rolling, centre and edge cracks were observed in the 9.1 wt.% and 9.7 wt.% Al steels due to brittle Fe3Al intermetallic and κ-carbide, higher solid solution hardening and hardness. In contrast, the 6.8 wt.% Al steel does not exhibit any cracks during cold rolling. Therefore, to prevent cracking problems in high Al steels, warm rolling was carried out at intermediate rolling temperatures range of 200 ℃ and 500 ℃.