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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 .
Untempered martensite is low in toughness and therefore brittle.Tempered martensite gives steel good hardness and high toughness as can be seen below, and is largely used for medical surgical instruments, such as scalpels, razors, and internal clamps. [11]
The term "martensite" was originally coined to describe the rigid and finely dispersed constituent that emerges in steels subjected to rapid cooling. Subsequent investigations revealed that materials beyond ferrous alloys, such as non-ferrous alloys and ceramics, can also undergo diffusionless transformations.
However, greater undercooling by rapid quenching results in formation of martensite or bainite instead of pearlite. This is possible provided the cooling rate is such that the cooling curve intersects the martensite start temperature or the bainite start curve before intersecting the P s curve. The martensite transformation being a ...
Further excessive heat-treatment brings about the decomposition of the martensite and reversion to austenite. Newer compositions of maraging steels have revealed other intermetallic stoichiometries and crystallographic relationships with the parent martensite, including rhombohedral and massive complex Ni 50 (X,Y,Z) 50 (Ni 50 M 50 in simplified ...
This phase is called martensite, and is extremely hard due to a combined effect of the distorted crystal structure and the extreme solid solution strengthening, both mechanisms of which resist slip dislocation. All hardening mechanisms introduce crystal lattice defects that act as barriers to dislocation slip.
It is a martensitic phase in nature, but is not the martensite that is responsible for the shape memory and superelastic effect. In connection with nitinol, "martensite" normally refers to the B19' monoclinic martensite phase, rather than the R-phase. The R-phase competes with martensite, is often completely absent, and often appears during ...
AerMet alloy is an ultra-high strength type of martensitic [1] alloy steel.The main alloying elements are cobalt and nickel, but chromium, molybdenum and carbon are also added.