Effect of hot rolling on bonding characteristics and impact behavior of a laminated composite material based on UHCS-1.35 pct C

Two different hot rolling routes were developed to study the influence of thermomechanical factors on interface bonding, characterized by shear tests, and impact behavior of laminates containing five layers of ultrahigh carbon steel (UHCS-1.35C) and five layers of mild steel (MS-0.091C). The relationship between processing and microstructure has been studied by scanning electron microscopy (SEM) and electron dispersive spectroscopy examinations. It has been observed that the path for thickness reduction in the hot roll processing affects fundamentally the bond between layers. Specifically, a severe initial thickness reduction of 25 pct in the first cycle, allowing an important processing temperature drop (from 765 degrees C to 600 degrees C), produces a strong bond, which prevents delamination. On the contrary, the application of soft and gradual thickness reductions results in less tough bonds that permit delamination and, therefore, multiply the impact resistance.