Control of fiber wrapping angle of fiber composite tube and the influence of the angle on its mechanical properties

The heat treatment process before nitriding for cold working die steel SKD11 is very important. On once hand, cold working die must have proper mechanical properties; on the other hand, the temperature must be high enough to apply continuous nitriding to make the nitriding layer with proper thickness and hardness. This paper presents the research on the influences of quenching and adjusting temperature of SKD11 steel to the microstructure and hardness in order to choose appropriate heat treatment for required mechanical properties of cold working die and continuous nitriding. The quenching temperature was researched on the basis of maximize dissolution of carbide in austenite when austenitizing to receive enough retaining austenite after quenching, so that when apply tempering it gives the second hardness. Establishing the relationship between hardness and tempering temperature allowed to find out second hardness area and choose suitable nitriding temperature for cold working die which reserves their best mechanical properties and microstructure.