Carbon steel casting parts' organization is characterized by coarse grains and uneven, which is reasoned by the slower cooling rate in the casting mold. Carbon Steel Casting parts' size is generally larger, and without forging process, so the carbon steel castings have more obvious segregation, and generally have dendrites, columnar, network organization and widmanstatten structure. Carbon steel casting parts have large internal stress, poor mechanical performance and especially lower section shrinkage and toughness. That is because the forming method of carbon steel casting parts is simple and easy to process.
Carbon steel casting parts can not be used directly as their low plasticity and toughness. To improve mechanical properties and the properties of ordinary carbon steel casting parts can be often heat-treated to refined grains, eliminating widmanstatten structures and casting stress.
More complex shapes easily lead to distortion and cracking of carbon steel castings to the annealing; shape is relatively simple, modest thickness of carbon steel castings have to be normalized; size of the larger pieces of carbon steel commonly used normalizing and tempering treatment; shape simple and demanding mechanical properties of carbon steel castings should be quenched and tempered. Quenching and annealing or normalizing the former general, and some by direct quenching cast. The latter process is simple, short production cycle, low cost. Heat treatment, the size or shape of larger complex pieces of carbon steel heating rate must be fast or carbon steel casting parts prone to deformation or cracking. Carbon steel casting parts large heating rate generally limited to 50 ~ 100 ℃ / h, small can control 100 ~ 200 ℃ / h. Carbon Steel Casting parts of annealing and normalizing temperature than the corresponding grades of carbon steel heat processing conditions appropriate higher, longer holding time to a number of appropriate, to ensure uniformity of composition and organization.