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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. [1] In plain-carbon steel, austenite exists above the critical eutectoid temperature of 1000 K (727 °C); other alloys of steel have different eutectoid temperatures.
Martensite in AISI 4140 steel 0.35% carbon steel, water-quenched from 870 °C. Martensite is a very hard form of steel crystalline structure. It is named after German metallurgist Adolf Martens. By analogy the term can also refer to any crystal structure that is formed by diffusionless transformation. [1]
In steel it produces a bainite microstructure whereas in cast irons it produces a structure of acicular ferrite and high carbon, stabilized austenite known as ausferrite. It is primarily used to improve mechanical properties or reduce / eliminate distortion. Austempering is defined by both the process and the resultant microstructure.
Bainite is a plate-like microstructure that forms in steels at temperatures of 125–550 °C (depending on alloy content). [1] First described by E. S. Davenport and Edgar Bain, [2] [3] it is one of the products that may form when austenite (the face-centered cubic crystal structure of iron) is cooled past a temperature where it is no longer thermodynamically stable with respect to ferrite ...
Austenite is slightly undercooled when quenched below Eutectoid temperature. When given more time, stable microconstituents can form: ferrite and cementite. Coarse pearlite is produced when atoms diffuse rapidly after phases that form pearlite nucleate. This transformation is complete at the pearlite finish time (P f).
The metal part is then removed from the bath and cooled in air to room temperature to permit the austenite to transform to martensite. Martempering is a method by which the stresses and strains generated during the quenching of a steel component can be controlled. In martempering, steel is heated to above the critical range to make it all ...
In carbon steel, cementite precipitates from austenite as austenite transforms to ferrite on slow cooling, or from martensite during tempering. An intimate mixture with ferrite, the other product of austenite, forms a lamellar structure called pearlite. The iron-carbon phase diagram
Faucet dripping water. Structure of the water molecule (H 2 O) The following outline is provided as an overview of and topical guide to water: Water – chemical substance with the chemical formula H 2 O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds.