Martensitic stainless steel is a stainless steel alloy with a carbon content of less than one percent. Instead, martensitic stainless steel primarily consists of iron and chrome, plus smaller amounts of nickel, copper, and other metals. This special blend of metals gives this material several advantages over traditional carbon steel, including strength and corrosion resistance. Martensitic stainless steel is named after its inventor, German scientist Adolf Martens, who developed this particular form of steel during the late 19th century. In some parts of the world, this material is known as Staybrite® after an early brand name product.
The amount of chrome used to make martensitic stainless steel determines both the properties of the metal and its grade, or quality. Generally, this product contains between 12 and 14 percent chromium, with higher amounts used to produce higher grades. It may also include lead, copper, and other metals known for their strength or corrosion resistance. The higher the chromium content, the better the steel is able to resist rust and corrosion. Lower grades may be used for tools, building facades, and automotive detailing, while higher grades are required for jewelry manufacturing, food storage, and weaponry.
To make martensitic stainless steel, manufacturers blend the desired mix of metal alloys under high temperature levels. As it hardens, the steel is subject to rapid cooling or quenching. During cooling, steel may be placed into a vat of brine, oil or even water depending on the desired properties. This combination of heating and cooling helps to balance the hardness, corrosion resistance and internal strength of this material.
Heating and quenching steel helps to enhance its strength and wear resistance, and leaves the material very hard. Adding chromium to any steel alloy gives it a natural level of resistance against rust and corrosion. This means that this material can be used outdoors or in a marine environment without a great deal of maintenance. Unlike many other metals, this material remains strong at high temperature levels, though it may become weaker under freezing temperatures. Martensitic stainless steel is highly machinable and can be welded using standard equipment and techniques.
As steel is hardened through heating and quenching, it also becomes more brittle. This means that the steel can withstand wear and heavy use, but is vulnerable to cracks or shattering if exposed to high levels of shock or heavy impact. Generally, manufacturers must work to balance hardness and brittleness at the best level for each type of application.