Rockwell

Rockwell hardness testing is a general method used for measuring the bulk hardness of metallic materials. Hardness testing does not give a direct measurement of any performance properties, hardness correlates with strength, wear resistance, and other properties. It is widely used for material evaluation due to its simplicity and low cost relative to direct measurement of many properties.

Rockwell hardness testing is an indentation testing method. Common regular Rockwell hardness scales include B and C for metals and M and R for polymers. An indenter such as a diamond is impressed into the test sample at a prescribed load to measure the material's resistance to deformation. A Rockwell hardness number is displayed from the depth of permanent deformation of the sample after application and removal of the test load. It is then determined by the numbers the degree of hardness - the higher the Rockwell number, the harder the blade is. Depending on what the blade is to be used for determines how hard to temper. For example, a quality chef's knife should be in the 57 range. Any softer then 54 usually means the blade will not sharpen very well or will not hold its edge very long.

The Bolster

The raised thick part between the blade and the handle is called the Bolster the bolster usually distinguishes the knife as fully forged. The bolster acts as a guard providing safety balance, sturdiness, and comfort.

Beware of companies that manufacture knives with an imitation bolster as these knives are invariably cheaper in quality compared against a "one piece fully forged" knife.

Tang

The portion of the knife blade that becomes the handle. There are many shapes but these are dependant on what will be done with the knife. For example an injection molded handle requires a completely different shape compared against the requirement for a full tang handle.

Forge

A Forge or large oven is required to heat the metal thus allowing the ability to shape it by hammering.

Drop Forge

The process in which heated metal is formed by a powerful strike from a hammer.

Temper

The process in bringing metal to the required degree of hardness and elasticity by heating then cooling.

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