Enhancement of Strength by Multiple Rolling at Room Temperature in the 1045 Steel Prepared by Aluminothermic Reaction

摘要

> The effects of cold rolling on the microstructure and mechanical properties of 1045 steel prepared by aluminothermic reaction casting method are investigated. It is found that an ultrafine‐grained ferrite ( α )?+?submicron/nano‐cementite particle ( θ ) structure is formed by rolling at room temperature with different thickness reduction. With the increase of thickness reduction, many lamella cementites are squeezed, a portion of cementite is crushed, the dislocation density increases, meanwhile the tensile strength is improved significantly. The underlying mechanisms of enhancing mechanical properties are analyzed, with a focus on the heterogeneous composite structure of a soft fine‐grained matrix embedded with hard nano‐scale cementite particles. The yield strength and ultimate tensile strength are increased from 256?MPa and 490?MPa (As‐casting) to 939?MPa and 956?MPa at 84% thickness reduction. The tensile strength of rolled steel with 70% thickness reduction is 1.5 times than common 1045 carbon steel, but it also has a considerable ductility, resulting from the enhancement caused by refined ferrite grains and cementite particles.