PayPal

Sign up for PayPal and start accepting credit card payments instantly.

Thursday, March 13, 2008

Microstructurelles mapping of manganese austenitic steel-3401 in the process of rapid cooling

The unique properties of the steel Hadfield manganese (1.2% carbon and 12-14% manganese), high strength, high fracture toughness and wear resistance and impact do the heaviest load Steel very useful in a variety of applications, such as railways, the mill liners, jaws and crushing cones, impact hammer, and even a bullet-proof helmet. It is used in the usuallually austenitic state. An industry standard for the practice of Hadfield steel was annealed solution is to treat heat materials to 1000 ° -1090 ° C for up to 1 hour followed by a plan of cooling water. This treatment led to the formation of solid carbide that causes brittleness and austenite still pure. To alleviate this condition is also hardened, resulting in the reprecipitation of carbides carbides and manganese in the grain boundaries followed by acicular rushed extending into the grain, as well as the emergence of troostite in the grain boundaries. This partial decomposition of austenite also depends on time and temperature tempering condition.
In recent years, many attempts have been made to improve the properties of the alloy base Hadfield by varying composition and the work of heat treatment and Rao discussed Kutumbarao based alloys Fe-Mn-C for austenitic steels resistance wear and Fe-Mn - Cr austenitic steels used for corrosion resistant. In the Fe-C-Mn steel, development was directed towards increasing the number of relatively low yield in the annealed by precipitation hardening to the state of fine carbides, often complex, requiring several steps heat treatments . The big inter-granular precipitation may take place during the various stages of heat treatments and lead it to its fragility in the troupe to the form components. The shape casting components are widely used in applications railways. Two important steps in the process of casting aroused great interest because they will influence the final mechanical properties, the loss of some alloying elements (eg, Mn, C) of the surface and the reverse process, which is the transfer of hardware (eg, P, C, N, O, Si) of the casting. Sometimes the loss of Mn in the surface layers can be important, for example 10-12%, significantly reducing the abrasion resistance and fatigue life of the cast component.
The mapping of morphological phenomena, in particular the development of the microstructure with heat treatment is a tool well known in metallurgical engineering. This involves the identification of microstructural features expected expected observed by previous work and linking them to the comments in the course work.In this work, the heat - 3401 in the process of rapid cooling is studied using the mapping of microstructures. In this study, emphasis is on the effect of iso-thermal processes on the formation and decomposition of the new investigation on steel in various stages of hardening and holding temperatures times.

No comments: