This is the most common type of stainless steel, accounting for up to 70% of all stainless steel production.
Main Image: Martensite is a hard form of steel crystalline structure formed through the displacive transformation and have a distinguishing body-centered tetragonal crystalline structure. Martensites consist of a group of hard minerals which occur as plate-shaped crystal granules. 1 Martensite has a lower density than austenite, so that the martensitic transformation causes a moderate volume change. 2  More important factor than the volume change is the shear strain that has a magnitude nearly 0.26 that find out the shape of the martensite plates. Austenite, also known as gamma-phase iron (γ-Fe), is a metallic, non-magnetic allotrope of iron or a solid solution of iron, with an alloying element. The metal is heated into the austenite region of the iron-cementite phase diagram and then quenched in a salt bath or other heat extraction medium that is between temperatures of 300–375 °C (572–707 °F). Martensite is formed in carbon steels by the rapid cooling (quenching) of austenite at such a high rate that carbon atoms do not have time to diffuse out of the crystal structure in large enough quantities to form cementite (Fe 3 C). One of the differences between the two phases is that martensite has a body-centered tetragonal (BCT) crystal structure, whereas austenite has a face-centered cubic (FCC) structure. Austenitic – This is the most common type of stainless steel, accounting for up to 70% of all stainless steel production. Its versatility is in large part down to the fact that it can be formed and welded with successful results. Steel Plates. To the lay person, one piece of stainless steel may seem just like any other, but the truth of the matter is a little bit more complicated. Austenite and ferrite. Austenite was originally used to describe an iron-carbon alloy, in which the iron was in the face-centred-cubic (gamma-iron) form. It is now a term used for all iron alloys with a basis of gamma-iron. Austenite in iron-carbon alloys is generally only evident above 723°C, and below 1500°C, depending on carbon content. However, it can be retained to room temperature by alloy additions such as nickel or manganes The percentage of retained austenite increases from insignificant for less than 0.6% C to 13% retained austenite at 0.95% C and 30–47% retained austenite for a 1.4% carbon steels. A very rapid quench is essential to create martensite. For a eutectoid carbon steel (0.78% C) of thin section, if the quench starting at 750 °C and ending at 450 °C takes place in 0.7 seconds (a rate of 430 °C/s) no pearlite will form and the steel will be martensitic with small amounts of retained austenite. One of the differences between the two phases is that martensite has a body-centered tetragonal (BCT) crystal structure, whereas austenite has a face-centered cubic (FCC) structure. Stainless Steel. Stainless steel is a modern alloy developed in the early 1900’s after metallurgists discovered that chromium-iron alloys displayed superior corrosion resistance to carbon steel alloys. The first products using stainless steel were produced in 1908 and the first patents were granted in 1912. The corrosion resistance that is unique to stainless steel is the result of a transparent passive film of chromium oxide forms on the surface of the steel and protects it from oxidation. Martensite has a lower density than austenite, so that the martensitic transformation results in a relative change of volume. Of considerably greater importance than the volume change is the shear strain which has a magnitude of about 0.26 and which determines the shape of the plates of martensite. One of the differences between the two phases is that martensite has a body-centered tetragonal (BCT) crystal structure, whereas austenite has a face-centered cubic (FCC) structure. Type 410. Basic martensitic grade, containing the lowest alloy content of the three basic stainless steels (304, 430, and 410). Low cost, general purpose, heat treatable stainless steel. Used widely where corrosion is not severe (air, water, some chemicals, and food acids.  Martensitic – This type of steel shares some characteristics with ferritic, but boasts higher levels of carbon, up to a full 1%. This means that they can be tempered and hardened and are thus highly useful in situations where the strength of the steel is more important than its resistance to corrosion. Steel Plates. To the lay person, one piece of stainless steel may seem just like any other, but the truth of the matter is a little bit more complicated.
http://www.innovateus.net/science/what-martensite https://en.wikipedia.org/wiki/Austenite https://en.wikipedia.org/wiki/Martensite http://www.brownmac.com/blog/what-is-stainless-steel http://www.twi-global.com/technical-knowledge/faqs/material-faqs/faq-what-are-the-microstructural-constituents-austenite-martensite-bainite-pearlite-and-ferrite/ https://en.wikipedia.org/wiki/Martensite http://www.onealsteel.com/stainless-steel.html https://en.wikipedia.org/wiki/Martensite http://www.spiusa.com/stainlesssteel_overview.php http://www.brownmac.com/blog/what-is-stainless-steel
what is austenitic and martensitic