Blade manufacturing

Steel blades can be manufactured either by being forged or stamped. Forged blades are made in an intricate, multi-step process, often by skilled manual labor. A chunk of solid or powdered steel alloy is heated to a high temperature, and pounded while hot to form it. The blade is then heated above critical temperature (which varies between alloys), quenched in an appropriate quenchant, and tempered to the desired hardness. After forging and heat-treating, the blade is polished and sharpened. Forged blades are typically thicker and heavier than stamped blades, which is sometimes advantageous. Stamped blades are cut to shape directly from cold-rolled steel, heat-treated for strength, then ground, polished, and sharpened. Though they are not preferred by most professional chefs, several popular knife brands, such as Global and Shun, do use stamped and heat-treated blades in their premium knives. Stamped blades can often, but not always, be identified by the absence of a bolster. Forging is a manufacturing process involving the shaping of metal using localized compressive forces. Forging is often classified according to the temperature at which it is performed: "cold", "warm", or "hot" forging. Forged parts can range in weight from less than a kilogram to 580 metric tons.[1][2] Forged parts usually require further processing to achieve a finished part. In materials science, quenching is the rapid cooling of a workpiece to obtain certain material properties. It prevents low-temperature processes, such s phase transformations, from occurring by only providing a narrow window of time in which the reaction is both thermodynamically favorable and kinetically accessible. For instance, it can reduce crystallinity and thereby increase toughness of both alloys and plastics (produced through polymerization). In metallurgy, it is most commonly used to harden steel by introducing martensite, in which case the steel must be rapidly cooled through its eutectoid point, the temperature at which austenite becomes unstable. In steel alloyed with metals such as nickel and manganese, the eutectoid temperature becomes much lower, but the kinetic barriers to phase transformation remain the same. This allows quenching to start at a lower temperature, making the process much easier. High speed steel also has added tungsten, which serves to raise kinetic barriers and give the illusion that the material has been cooled more rapidly than it really has. Even cooling such alloys slowly in air has most of the desired effects of quenching. Stamping (also known as pressing) includes a variety of sheet-metal forming manufacturing processes, such as punching using a machine press or stamping press, blanking, embossing, bending, flanging, and coining.[1] This could be a single stage operation where every stroke of the press produces the desired form on the sheet metal part, or could occur through a series of stages. The process is usually carried out on sheet metal, but can also be used on other materials, such as polystyrene.