Synergistic Investigations of Post‐Deformation Annealing and Initial Microstructure on the Mechanical Properties of High Strength Low Alloy (HSLA)‐100 Steel

Abstract

A high strength low alloy (HSLA)‐100 steel with different initial microstructures (ferrite and martensite) is processed by cold rolling at room temperature to the reduction of thickness about 70%. It is found that the recrystallization kinetics of the sample with a martensitic microstructure is higher than the sample with a ferritic microstructure. Moreover, the results show that the partitioning factor of substitution alloying elements is less effective than the strain in the martensitic phase transformation. Also, hardness results show that the samples with a martensitic microstructure have drastic drop compared with the samples with a ferritic microstructure, which is related to continuous recrystallization. Remarkable ultimate tensile strength and elongation to failure (829 MPa and 27.7%, respectively) are achieved for cold‐rolled martensite after tempering at 625 °C for 360 min. Accordingly, it is also found that the reason for remarkable mechanical properties is the simultaneous presence of recrystallized fine‐grained and deformed martensite, which forms an inhomogeneous microstructure.

Weldability of Underwater Wet-Welded HSLA Steel: Effects of Electrode Hydrophobic Coatings

“…A number of cold cracks resulted from the presence of brittle structures in the HAZ, characterized by high hardness, with the highest amount of diffusible hydrogen in the deposited metal [39]. It was also proven that HSLA steels are materials in which the high cooling rate leads to creation of the brittle martensitic microstructure [53].…”

Experimental Investigation on the Inhomogeneities of Transverse Microstructure and Internal Stress of High‐Strength Low‐Alloy Hot‐Rolled Strip

“…During the cooling of the specimen after deformation, there was no external force at this stage, so the sources of strain in the specimen are the thermal strain from thermal contraction and the transformation strain from transformation expansion, [20,21] as shown in Equation (2).…”

“…Low-alloy high-strength hot-rolled strip is widely used in automotive, marine, and other mechanical engineering industries because of its favorable comprehensive mechanical properties. [1,2] It is mainly produced by thermomechanical control process (TMCP), which includes heating, hot rolling, laminar cooling, and coiling. During the laminar cooling process, the cooling rate at the laminar edge is faster than that at the laminar center.…”

The Role of Cold Rolling Reduction on the Microstructure and Mechanical Properties of Ultra-Low Carbon Bainitic Steel

“…Ultra-low carbon bainitic steel (UCBS) is widely used in ship manufacturing, offshore oil platforms, bridge construction, and aviation facilities due to its excellent strength, high ductility, good weldability, and low cost [1][2][3][4]. In previous studies, high strength UCBS was mainly obtained by controlling the microstructure through different methods, such as grain refinement [5,6], precipitation hardening during annealing (e.g., Nb, V, Mo, Ticontained carbides, Cu-rich precipitates) [3,[7][8][9] and deformation strengthening (i.e., shape controlling) [5,8,10,11].…”