How to improve the hardness of light burned magnesium ball

The strength and hardness of the magnesium ball can be improved by heat treatment. The following are the effects of various heat treatment. You can choose the appropriate heat treatment according to the situation by burning the magnesium ball lightly. Large crystal fused magnesia, if only to improve the hardness, surface quenching is recommended. The purpose of normalizing ductile iron is to obtain pearlitic matrix structure, refine grains and uniform structure, so as to improve the mechanical properties of castings. Sometimes normalizing is also the preparation of the structure of the surface quenching of ductile iron. Normalizing can be divided into high temperature normalizing and low temperature normalizing. The high temperature normalizing temperature is generally not more than 950~980 ℃, and the low temperature normalizing temperature is generally heated to 820~860 ℃. After normalizing, four people are generally required to remove the internal stress generated during normalizing.

In order to improve the mechanical properties of ductile iron, the castings are generally heated to 30~50 ℃ above Afc1 (Afc1 represents the final temperature of A formation during heating), and then quenched into oil after heat preservation to obtain martensitic structure. In order to properly reduce the residual stress after quenching, generally tempering should be carried out after quenching. The low-temperature tempering structure is tempered martensite plus residual bainite plus spheroidal graphite. This kind of structure has good wear resistance and is used for parts requiring high wear resistance and high strength. The medium temperature tempering temperature is 350-500 ℃, and the microstructure after tempering is tempered troostite plus spheroidal graphite, which is suitable for thick parts requiring good wear resistance, effective stability and elasticity. The high-temperature tempering temperature is 500-60D ℃. The tempered microstructure is tempered sorbite plus spheroidal graphite. It has good comprehensive properties of toughness and strength, so it is widely used in production.

Ductile iron can obtain high strength, good plasticity and toughness after isothermal quenching. The selection of heating temperature for multi-temperature quenching mainly considers to make the original structure fully A, without residual F, and also avoid the growth of A grain. The heating temperature is generally 30~50 ℃ above Afc1, and the isothermal treatment temperature is 0~350 ℃ to ensure the lower bainite structure with comprehensive mechanical properties. After isothermal quenching of rare earth magnesium aluminum ductile iron σ b=1200～1400MPa， α k=3～3.6J／cm2，HRC＝47～51。 However, attention should be paid to adding another tempering process after isothermal quenching.