Abstract

Superior strength-ductility synergy of 1045 carbon steel produced by aluminothermic reaction casting method was obtained through large deformation rolling at ambient temperature and subsequent annealing, meanwhile, a heterogeneous composite structure was fabricated. The heterogeneous structural 1045 carbon steel consists of “soft” microcrystalline/ultrafine grained (UFG) ferrite and “hard” cementite nanoparticles. The outstanding strength-ductility synergy was primarily attributed to the microstructure characteristics about the “soft/hard” interfaces of heterogeneous composite structure. The strength was improved due to the second phase reinforcement of hard cementite nanoparticles and decreasing of ferrite grain size, meanwhile, the back stress hardening capacity of “soft/hard” phase also resulted in the high strength. And the favorable ductility was ascribed to the generation of geometrically necessary dislocations (GNDs) around “soft/hard” interfaces, which resulted in the high work hardening capability of heterogeneous structural 1045 carbon steel. It is remarkable that tensile strength (∼ 1190 MPa) and high yield strength (∼ 1118 MPa) and good ductility (∼10.6%) can be simultaneously acquired for the cold rolled 1045 steel after annealing at 673 K for 1 h.

Graphic Abstract

摘要

通过在环境温度下进行大变形轧制并随后进行退火，获得了通过铝热反应铸造法生产的1045碳钢的优异的强度-延性协同作用，同时制造了异质复合结构。异质结构1045碳钢由“软”微晶/超细晶粒（UFG）铁氧体和“硬”渗碳体纳米颗粒组成。出色的强度-延展性协同作用主要归因于异质复合结构“软/硬”界面的微观结构特征。由于硬质渗碳体纳米颗粒的第二相增强和铁素体晶粒尺寸的减小，强度得到了提高，同时，“软/硬”相的背应力硬化能力也导致了高强度。良好的延展性归因于“软/硬”界面周围几何必要位错（GND）的产生，这导致了异质结构1045碳钢的高加工硬化能力。值得注意的是，在673 K退火1 h后，冷轧1045钢可同时获得抗张强度（〜1190 MPa）和高屈服强度（〜1118 MPa）和良好的延展性（〜10.6％）。

图形摘要