Trip steel

Trip steel
Iron Carbon Alloy Phases
	Ferrite ( solid solution of C intercalation in α- iron with body-centered cubic lattice); Austenite ( solid solution of C intercalation in γ- iron with a face-centered cubic lattice); Cementite (iron carbide; Fe 3 C metastable high carbon phase); Graphite stable high carbon phase;
Iron Carbon Alloy Structures
	Ledeburite ( eutectic mixture of crystals of cementite and austenite, which turns into perlite when cooled); Martensite (highly supersaturated solid carbon solution in α- iron with body-centered tetragonal lattice); Perlite ( eutectoid mixture consisting of thin alternating plates of ferrite and cementite); Sorbitol (dispersed perlite); Troostitis (fine perlite); Beynite (Ustara: needle troostite) - ultrafine mixture of low carbon martensite crystals and iron carbides;
Become
	Structural steel (up to 0.8% C ); High carbon steel (up to ~ 2% C )( tool , die , spring , high-speed ); Stainless steel ( chrome alloy ); Heat resistant steel; Heat resistant steel; High strength steel;
Cast iron
	White cast iron (brittle, contains ledeburite and does not contain graphite); Gray cast iron ( graphite in the form of plates); Ductile iron (graphite in flakes); High-strength cast iron (graphite in the form of spheroids); Half-cast iron (contains both graphite and ledeburit);

Trip-steel , or PNP-steel ( English TRIP; Transformation-Induced Plasticity - plasticity, induced by transformation) - metastable high - strength austenitic steel with high plasticity.

Content

Use

Trip-steel compared with conventional (structural low-alloyed) steels have increased strength and ductility at the same time, that is, with equal strength ( yield strength ) they have 2-3 times more ductility, which provide them with advantages in the process of forming and molding. It is used for the manufacture of high-loaded parts: wires, cables, fasteners. These properties are most in demand in modern automotive industry, ^[1] as it can be used to produce more complex parts, providing greater freedom for engineers when choosing a design, optimizing (reducing) weight and general vehicle production technology. High alloying (production cost) and complex manufacturing techniques hinder the widespread use of these steels. In the future, trip-steel is likely to give way to the so-called steel type TWIP ( eng. TWIP; Twinning-Induced Plasticity - plasticity, induced by twinning ).

Production

To obtain the desired set of properties, it is necessary to carry out recrystallization followed by cooling at rates that allow suppressing carbon diffusion. The following structures arise:

ferrite;
iron carbide (which is why silicon alloy is used to reduce the formation of carbides);
high carbon austenite.

To relieve stresses, the structure is kept for a certain time at a temperature Tb in order to cool rapidly to room temperature. The following structures arise:

ferrite;
carbide saturated bainite;
metastable carbon saturated austenite.

Composition

The approximate chemical composition of the trip-steels alloyed with silicon (for example steel 30H9N8M4G2S2):

Carbon	Silicon	Chromium	Nickel	Manganese	Molybdenum
0.2—0.3%	up to 2.0%	8.0-14.0%	8.0–32.0%	0.5-2.5%	2.0–6.0%

Notes

↑ Titov V. Rolled steel for the automotive industry abroad (Rus.) // National Metallurgy. - 2004. - № 5 . - p . 84-89 . Archived July 10, 2012.

Links

New high-strength and heavy-duty materials with high plasticity
Transformation-Induced Plasticity (TRIP) Steel (English) (inaccessible link) . WorldAutoSteel . AI & SI. The appeal date is December 12, 2009. Archived November 21, 2009.

[1] Titov V. Rolled steel for the automotive industry abroad (Rus.) // National Metallurgy. - 2004. - № 5 . - p . 84-89 . Archived July 10, 2012.