Khan Waseem, Tufail Muhammad, Chandio Ali Dad
Materials and Surface Engineering Laboratory, Department of Metallurgical Engineering, NED University of Engineering and Technology, Karachi 75270, Pakistan.
Materials (Basel). 2022 Mar 16;15(6):2204. doi: 10.3390/ma15062204.
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 MoC (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.
为了保护民用和军用装甲车，人们使用先进钢材，这是由于其出色的机械性能、高防弹性能、易于制造且成本低廉。然而，改装后，重量成为突出问题。在这方面，人们提出了几种策略，包括对低厚度防弹钢或传统钢进行表面工程处理，此外还有新型合金和复合材料。因此，为了更好地了解这些材料在各种刺激下的反应，本研究采用了现有最先进的防弹钢。本研究的目的是更好地了解现有材料及其腐蚀行为。因此，在这方面，选择了两种厚度，即薄（6.7 - 7.0毫米）和厚（13.0 - 15.0毫米），此后分别称为低厚度（LT）和高厚度（HT）。随后进行了拉伸、夏比、显微维氏、纳米压痕、XRD、SEM - EDS和腐蚀测试等表征。在微观结构上，LT样品仅显示出ε - 碳化物沉淀，而HT样品同时含有ε - 碳化物和MoC（碳化钼）。然而，发现两个样品均为板条形态的回火马氏体。此外，与LT样品相比，HT样品的硬度更高，弹性模量和刚度更低。还检查了这两种合金的断裂表面，其中观察到韧性断裂模式。此外，还在盐水溶液中进行了腐蚀研究。结果表明，HT样品的腐蚀速率高于LT样品。根据观察结果进行了广泛讨论。
