The hardness of magnesium balls can be improved by heat treatment. The following provides various heat treatment effects. For light burned magnesium balls, you can choose the appropriate heat treatment according to the situation. If you just want to increase the hardness, surface quenching is recommended. The purpose of normalizing ductile iron is to obtain the pearlite matrix structure, and to refine the grains and uniform structure to improve the mechanical properties of the casting. Sometimes normalizing is also the preparation for surface quenching of ductile iron. Normalizing is divided into high temperature normalizing and low temperature normalizing. The high-temperature normalizing temperature generally does not exceed 950-980℃, and the low-temperature normalizing is generally heated to a common bending temperature range of 820-860℃. After normalizing, four people are required to deal with it to eliminate the internal stress generated during normalizing. Light burnt magnesia powder
In order to improve the mechanical properties of ductile iron, generally castings are heated to 30-50°C above Afc1 (Afc1 represents the final temperature of A formation during heating), and then quenched into oil to obtain a martensitic structure. In order to appropriately reduce the residual stress after quenching, tempering should generally be carried out after quenching. The low-temperature tempering structure is tempered martensite with residual bainite and spherical graphite. This kind of organization is good, and it is used for high-quality parts. The tempering temperature of the medium temperature is 350-500℃. The structure after tempering is tempered troostite plus spherical graphite, which is suitable for thick parts with good requirements, effective stability and elasticity. High temperature The tempering temperature is 500-60D℃, the structure after tempering is tempered Soxhlet made of spheroidal graphite, which has the comprehensive properties of good combination of toughness and strength, so it is widely used in production.
Ductile iron can be obtained after austempering, and it has both good ductility and toughness. The selection of the heating temperature for multi-temperature quenching is mainly considered to make the original structure A and F, while also avoiding the growth of A grains. The heating temperature is generally 30-50°C above Afc1, and the isothermal treatment temperature is 0-350°C to obtain a lower bainite structure with comprehensive mechanical properties. Rare earth magnesium aluminum ductile iron after isothermal quenching σb=1200～1400MPa, αk=3～3.6J/cm2, HRC=47～51. But pay attention to adding a tempering process after austempering.
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