Production process and technological requirements of Heat-resistant Castings

- Nov 14, 2018 -

Annealing of Heat-Resistant Castings


Heat-resistant castings are effective in slowly heating the metal at a certain temperature, then holding it for a while, then cooling it slowly to room temperature.


Normalizing of Heat-resistant Castings


The heat treatment process is to heat the metal to 30 ℃ above the critical temperature and cool in the air after proper holding time. It'sounds like normalizing and annealing. However, the cooling rate of normalizing a little faster, production cycle is short.


Quenching of Heat-Resistant Castings


During operation, the metal is effectively heated above the critical point, at which time, the structure and state of the metal will change-austenitization. We need to hold the metal for a certain amount of time to make this change, and then cool it at a rate greater than the critical cooling rate to get the metastable martensite structure or the lower bainite structure. This quick cooling method is usually like this: one is to cool the metal in water.

Tempering of Heat-resistant Castings


After the metal is hardened, it is heated to a temperature below the critical temperature. For a period of time, the microstructure of the metal can be evenly distributed and then cooled to room temperature, and a finished product with both strength, hardness, plasticity and toughness can be obtained.