Martensitic austempering and its advantages

　　In recent years, graded quenching has been further developed, not only graded quenching above MS point, but also graded quenching below MS point, or a combination of the two. MS point below the graded martensite isothermal quenching.

　　one or two grading isothermal above the MS point can minimize the temperature difference between the inside and outside of the workpiece. Then isothermal at a 1 temperature below the MS point to control the amount of austenite to martensite transformation (note: the amount of martensite transformation is related to the cooling temperature, martensite can be formed isothermally see the book "Martensite isothermal formation. In this way, in the process of isothermal, the martensite is tempered, and there is a part of the oad body in the isothermal formation of martensite, so that the quenching process can prevent the workpiece from cracking, and can get the smallest deformation. After isothermal quenching of martensite, a tempering treatment is usually carried out.

austempering (martempering) has many advantages.

　　1. due to the decrease in the use temperature of salt and alkali bath, the cooling capacity increases, so that martensite carbon isothermal tool steel with larger section can be quenched.

　　2. isothermal below MS point, oil can also be used, so special fast martensite is also produced instead of isothermal quenching oil and salt bath.

　　3. Thermal stress can be minimized because it can be successfully reduced above the MS point and tissue deformation stress can be reduced below the MS point.

　　due to the above advantages, isothermal quenching can process a wide range of martensitic steel tools, molds, tools and important structural parts, these steels include carbon tool steels, low alloy tool steels, medium carbon low alloy steels, high carbon low alloy steels, high carbon high alloy steels, etc. Martensite isothermal quenching should be widely used.