Ultrahigh Charpy impact toughness (~450J) achieved in high strength ferrite/martensite laminated steels

Abstract

Strength and toughness are a couple of paradox as similar as strength-ductility trade-off in homogenous materials, body-centered-cubic steels in particular. Here we report a simple way to get ultrahigh toughness without sacrificing strength. By simple alloying design and hot rolling the 5Mn3Al steels in ferrite/austenite dual phase temperature region, we obtain a series of ferrite/martensite laminated steels that show up-to 400–450J Charpy V-notch impact energy combined with a tensile strength as high as 1.0–1.2 GPa at room temperature, which is nearly 3–5 times higher than that of conventional low alloy steels at similar strength level. This remarkably enhanced toughness is mainly attributed to the delamination between ferrite and martensite lamellae. The current finding gives us a promising way to produce high strength steel with ultrahigh impact toughness by simple alloying design and hot rolling in industry.

Delamination toughening in a low carbon microalloyed steel plate rolled in the dual-phase region

“…Because the main crack is blunted obviously so that the specimen becomes a no notch one after delamination. This forceful delamination toughening phenomenon can be found in the studies of Zou et al [13] and Cao et al [34]. For instance, the upper shelf energy larger than 450 J and excellent low-temperature toughness (about 105 J at −196°C) are obtained in a medium-manganese steel plate.…”

Analysis of Ductile Fracture Obtained by Charpy Impact Test of a Steel Structure Created by Robot-Assisted GMAW-Based Additive Manufacturing

“…While studies have been conducted on mechanical properties, including tensile strength and hardness of materials created by additive manufacturing, little work can be found on the impact 2 of 12 toughness of these materials. Toughness is an important characteristic that can help study the ability to absorb energy as well as the ductile or brittle behavior of the structure [18]. Toughness may or may not be anisotropic, based on the welding process, microstructure, and grain size [19,20].…”

The empirical prediction of weight change and corrosion rate of low-carbon steel

“…The mechanical properties (see Table 1) of the low-carbon steel are relatively soft and weak but have outstanding ductility and toughness as shown by an ultimate tensile strength of 502 MPa, yield strength of 359 Mpa, elongation of 32.3% and young modulus of 18.87 Gpa [28,29]. The chemical composition of the metal plate material with an average C content of 0.231% (see Table 2) indicates that the cross-section specimen used in this study is the low-carbon steel or mild steel.…”