Interface Strengthening and Toughening Mechanism of Hot Rolled Multilayer TWIP/40Si2CrMo Steels

Abstract

Layered metal composites play an increasingly important role in aerospace, automotive, and nuclear energy. Compared with a single metal or alloy, the layered metal composite exhibits an excellent strong-plastic matching effect. In this paper, multilayer TWIP/40Si2CrMo steels with different hot rolling reductions were successfully fabricated by the vacuum hot rolling. The results show that the multilayer steels can improve the lower yield strength of TWIP steel and lower the fracture elongation of 40Si2CrMo steel. In addition, with the increase of the hot rolling reduction, the mechanical properties and interfacial bonding strength of multilayer steels were improved, while the size and number of interfacial oxides decrease, and the fracture mode was also changed. This shows that a higher hot rolling reduction will promote the breakage of the interface oxides and make them appear dispersed, thereby improving the bonding strength of the interface, effectively suppressing the delamination and local necking of the multilayer steel, and making the multilayer steel show a higher ability of uniform plastic deformation. At the same time, under the dual action of layer thickness scale and interface strengthening effect, the brittle layer of multilayer steel presents a multiple tunnel crack mode. It was beneficial to alleviate the stress concentration and further improve the strengthening and toughening effect of multilayer steel.