The process of hardened and tempered is called quenching heat treatment tempering process is on the temperature between 500-600 ℃.in this way, quenching and tempered can obtain great extent of adjustment bythe performance of the steel strip,its strength,ductility and toughness are more better,and with good mechanical properties 

 

The steel strips obtained quenched and tempered sorbite after heat treatment, tempered sorbite is formed martensite in tempering, and it tell the difference by on at least under and optical microscope of 500-600 times enlarged.the distribution of carbide ferrite matrix (including cementite) pellets of a composite structure. It is also a tempered martensite, and a mixture of ferrite and granular carbide.at this point the ferrite almost don't have the carbon supersaturation. carbides stable carbides,at normal temperature is a  balance organization

 

Quenched and tempered steel strip contains carbon and alloy quenched and tempered steel strips.in spite of carbon steel or alloy steel,the carbon content is strictly controled.if the carbon content is too high,although the strength of steel strips is high,the toughnes is not good enough,for example,the carbon content is too low,the toughness improved but the lack of strenth.so in order to get a better quenched overall performance,the general control of the carbon content of 0.30 -1%

 

When hardening and tempering,it requried the workpiece contains the entire cross section hardenability.so that the workpiece can obtained as fine needles quenched martensite microstructure dominated. by the tempered.to get an even tempered sorbite microstructure dominated.small factoried don't have the metallurgical analysis at every furnace.generaly for hardness testing,that is to say,it must be achieved the hardness requirement and to check Figure after quenching and tempering.