Characterization of Microstructure, Phase Composition, and Mechanical Behavior of Ballistic Steels

Abstract

For the protection of civil and military armored vehicles, advanced steels are used, due to their outstanding mechanical properties, high ballistic performance, ease of manufacturing and low cost. However, after retrofitting, weight is the prominent issue. In this regard, several strategies are being proposed, which include the surface engineering of either low-thickness ballistic steels or conventional steels, in addition to new alloys and composites. Therefore, to better understand the response of such materials under various stimuli, the existing state of the art ballistic steels was utilized in this study. The aim of this study was to better understand the existing materials and their corrosion behavior. Therefore, in this connection, two thicknesses were selected, i.e., thin (6.7–7.0 mm) and thick (13.0–15.0 mm), henceforth termed as low thickness (LT) and high thickness (HT), respectively. This was followed by characterization using tensile, Charpy, micro-Vickers, nanoindentation, XRD, SEM-EDS and corrosion tests. Microstructurally, the LT samples only exhibited ε-carbide precipitates, whereas the HT samples contained both ε-carbides and Mo2C (molybdenum carbides). However, both samples were found to be tempered martensite with a lath morphology. Moreover, higher hardness, and lower elastic modulus and stiffness were noticed in the HT samples compared with their LT counterparts. Fractured surfaces of both of these alloys were also examined, wherein a ductile mode of fracturing was observed. Further, a corrosion study was also carried out in brine solution. The results showed a higher corrosion rate in the HT samples than that of their LT counterparts. An extensive discussion is presented in light of the observed findings.

Algorithms to Estimate the Ductile to Brittle Transition Temperature, Upper Shelf Energy, and Their Uncertainties for Steel Using Charpy V-Notch Shear Area and Absorbed Energy Data

“…Charpy test results from multiple temperatures are necessary to enable the characterization of the transition from ductile behavior to brittle behavior. Thus, operators sometimes request "full Charpy curves", i.e., Charpy tests performed at multiple temperatures (8)(9)(10)(11)(12) to characterize the transition from ductile to brittle behavior and upper shelf energy.…”

“…In the early 1900s, various impact tests were developed, originally to test the quality of armor plate and boiler steels, and the ASTM E23 method for Charpy impact testing procedure was tentatively released in 1933 [1]. The use of Charpy testing has expanded greatly, and examples of industries that rely on Charpy testing today include shipbuilding [7][8][9], nuclear power [10,11], armor [12], rail [13,14], construction [15], steam turbine [16], piping and pressure vessel [17][18][19], liquified natural gas storage [20], hydrogen storage [21], additive manufacturing [22], aluminum alloy development [23], and composites [24]. The principles and methods described in this paper are relevant to many critical structural applications but will be analyzed and discussed with respect to steel line pipes widely used in natural gas and hazardous liquid pipelines.…”

The Influences of Nb Microalloying and Grain Refinement Thermal Cycling on Microstructure and Tribological Properties of Armox 500T

“…Worldwide infrastructure and the special-purpose vehicles utilized by civilian and military forces extensively rely on advanced protective materials, including armor steels, composites, and ceramics, to ensure protection against various threats [1][2][3][4]. Moreover, the growing demands for improved fuel efficiency, reduced greenhouse gas emissions, and enhanced safety and crash-resistant performance have made high-strength lightweight vehicles a top priority for manufacturers [5,6].…”