The process of hardening steel using temperature treatment is similar to the stresses of what happens to rubber and plastic lines when they are cooled down and heated up quickly. (mechanics.stackexchange.com)
Speaking of blades, the saw is equipped with hardened steel blades that you do not need to sharpen again. (geekwrapped.com)
Installation involves partly disassembling the vehicle, welding hardened steel panels to the body and adding multi-layered ballistic glass several inches thick. (canadianbusiness.com)