Table of Contents
What is austenite and martensite?
The crystal structure found at high temperatures is the parent phase, often referred to austenite, and the phase that results from a martensitic transformation is called martensite. The shape memory effect is a direct consequence of a reversible transformation between austenite and martensite.
How austenite is formed?
Heating white cast iron above 727 °C (1,341 °F) causes the formation of austenite in crystals of primary cementite. Austenite is formed by diffusion of carbon atoms from cementite into ferrite.
What is austenite and how is it formed?
austenite, solid solution of carbon and other constituents in a particular form of iron known as γ (gamma) iron. This is a face-centred cubic structure formed when iron is heated above 910° C (1,670° F); gamma iron becomes unstable at temperatures above 1,390° C (2,530° F).
What is austenite used for?
10 Applications Austenitic stainless steels are used for domestic, industrial, transport, and architectural products based primarily on their corrosion resistance but also for their formability, their strength, and their properties at extreme temperatures.
When does austenite form what is it made of?
Austenite is a solid solution of mostly iron and carbon. It has a face-centered cubic crystal structure. Austenite only forms when an iron-based alloy is heated above about 750°C (1382°F) but not above about 1450°C (2642°F). Austenite keeps its form at room temperature when special alloying elements have been added to the iron-based alloy.
Where can you find austenite in stainless steel?
Austenite is probably most commonly known for its presence in austenitic stainless steels. Austenite exists in these stainless steels at room temperature because of their high amounts of nickel. Nickel has special properties that promote the formation of austenite in steel and other iron-based alloys.
Why was austenite named after Sir William Austen?
The face-centered cubic structure of austenite also allows it to hold higher amounts of carbon than other steel crystal structures. Austenite was named in honor Sir William Chandler Roberts-Austen, who created the first iron-carbon phase diagram in the 19th century.
What does it mean to heat iron to austenite?
Austenitization means to heat the iron, iron-based metal, or steel to a temperature at which it changes crystal structure from ferrite to austenite. An incomplete initial austenitization can leave undissolved carbides in the matrix.