Application of cross-rolling and austempering–tempering to the production of rotary cutting tools

Fabrication of guided rotary tools requires perfectly levelled thin plates having an excellent combination of high strength and toughness. Uniformity of the mechanical properties is another challenge in the manufacturing process of these tools. The present research studies the influence of cross-rolling and austempering–tempering heat treatment on the microstructure, texture, levelness, and mechanical properties of the AISI 8670 steel used for making circular cutting tools. Actual size saw blades were produced with the new method, and the results were compared with those of commercial saws made with the conventional approach out of the same material. Cross-rolling homogenized the tensile properties of the rolled and heat-treated sheets due to the development of an intense and uniform {100} components of α and ε fibers along in-plane directions. The distinctive uniform texture induced by cross-rolling notably increased the material’s resistance against the neutralization of the as-rolled texture and softening during heat treatment. Post-deformation austempering–tempering resulted in a microstructure of lower bainite that helped minimize distortion while achieving excellent flexural (~ 3.4 GPa) and tensile (~ 1.74 GPa) strength. Alongside high strength, the austempered–tempered plates showed significant elongation in both tensile (8%) and bending (7%) modes.