Heat treatment of steel castings
Heat treatment of steel castings steel castings should be in the heat treatment before use. Because steel castings under cast that exist within the pores, cracks, shrinkage, and shrinkage, coarse grains, organization and uneven residual stress and other casting defects, so that the strength of steel parts, especially the plasticity and toughness greatly reduced. For the grain refinement, uniform within the organization and eliminate stress, steel pieces must be normalizing or annealing. Normalizing treated steel, its mechanical properties after annealing than the high, costs low, it used more often. However, normalizing treatment will cause a large internal stress than the annealed, only applies to the carbon content of less than 0.35% of the steel castings.
Because low-carbon steel casting plastic is good, not easy to crack when cooling. To reduce stress, steel parts in normalizing after the high-temperature tempering should be carried out. For the carbon content ≥ 0.35%, structural complexity and is easy to produce cracks in steel castings, can only annealing. Steel castings should not be quenched, otherwise easy to crack.