Product Introduction

Heat treatment and cooling of ductile casting

The metal working temperature and the temperature difference of each part play an important role in the cooling temperature field of nodular casting. The forced water cooling and air cooling of the metal type local overheating area is to ensure that the area maintains a normal working temperature, improve production efficiency, and eliminate overheating to ensure a normal cooling temperature field. The metal type operating temperature control is more advanced and effective means to control the cooling water outlet temperature, outlet temperature * cooling cycle water circulation speed adjustment. In addition, for the local thick hot joint parts can also be embedded with high thermal conductivity or large heat storage metal blocks, or adjust the thickness of the coating layer and the type of coating to ensure that the cast to form a reasonable cooling temperature gradient, eliminate local shrinkage defects.

The heat treatment of spheroidal graphite castings refers to the control of heating temperature, holding time and cooling speed according to a certain heat treatment specification, and the change of the structure of the alloy. The main purpose is to improve mechanical properties, enhance corrosion resistance, improve processing performance, and obtain dimensional stability.

In order to improve the actual effect of stress relief annealing, the heating temperature should be the best to reach the temperature of complete unloading after the ductile casting. When the temperature is lower than the last complete unloading temperature, the higher the heating temperature, the more sufficient the stress relief. However, the heating temperature is too high, will cause the ductile casting structure changes, thus affecting the performance of the ductile casting. For gray cast iron, the heating temperature is too high, will make the eutectoid cementite graphitization, so that the strength and hardness of nodular casting reduce. For white cast iron, the heating temperature is too high, will also cause the eutectoid cementation decomposition, so that the hardness and wear resistance of spheroidal graphite castings are greatly reduced.

The heating temperature of ductile casting stress relief annealing is 550℃. When the cast iron contains alloying elements that stabilize the matrix structure, the stress relief annealing temperature can be appropriately increased. The low alloy gray iron casting is 600℃, and the high alloy gray cast iron can be increased to 650℃. The heating speed is generally 60 ~ 100℃. The holding time can be calculated according to the following empirical formula: H"2~8 range of selection, the unit of the thickness of the formula is millimeter, the unit of the holding time is hour, H" in the range of 2~8 selection. Spheroidal ink castings with complex shapes and requiring full stress relief should have a larger H" value. With the furnace cooling speed should be controlled below 30 ° C /h, the general nodular casting cold to 150 ~ 200 ° C, the shape of complex nodular casting cold to 100 ° C.

Detection Systems

Copper Silica Sol Investment Casting

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