investment casting base trays, furnace grids, charging baskets made from heat resistant steel castings
Heat treatment process
The heating temperature is one of the important process parameters in heat treatment process, and selecting and controling heating temperature is a major problem to ensure the quality of heat treatment. Heating temperature is subjuct to metal material and the purpose of heat treatment, but generally heating above the phase-transition temperature in order to obtain high temperature organization.In addition, transformation will take some time, so when heating temperature of metal surface meets the required temperature, it still must keep a certain time at the temperature to make the internal and external temperature accordance and ensure the microstructure transferming ing completely, this period of time is called the time of heat preservation. Usually,there is no the time of heat preservation, because the heating speed is fast when heating is used high energy density and the surface is heat treated, and the time of heat preservation by the chemical heat treatment tends to be long.
Cooling is the indispensable step in the process of heat treatment, different process should adopt different cooling method,the key is to control the cooling rate.Generally, speed of quenching cooling is faster than speed of normalizing cooling, speed of normalizing cooling is faster than speed of annealing cooling, and speed of annealing cooling is the slowest. But different steel grades have different requirement, such as empty hard steel can be hardened by normalizing cooling speed.uire�*,n0\ �� nbsp;as empty hard steel can be hardened by normalizing cooling speed.