Effect of Casting Sand and Casting Temperature on Ingot Quality
Effect of casting temperature on ingot quality
1 Impact on the organization.
Increasing the casting temperature increases the tendency of ingot grains to crystallize. Increasing the casting temperature within a certain range, the ingot liquid cavity deepens, the temperature gradient of the crystal front becomes steeper, the cooling rate during crystallization is large, and the intracrystalline structure is refined, but the tendency to form columnar crystals and feather crystal structures increases at the same time. Increasing the casting temperature will also reduce the size of suspended crystals in the liquid cavity, so the tendency to form primary crystals becomes lower, the exhaust gas shrinking conditions are improved, and the density is increased. Decrease the casting temperature, the melt viscosity will increase, the shrinkage conditions will become worse, and loose and oxide film defects will increase.
2 Effect on mechanical properties.
If the casting temperature is increased within a certain range, the as-cast mechanical properties of hard alloy ingots can be correspondingly improved, but the as-cast mechanical properties of soft alloy ingots have a tendency to decrease due to the influence of grain size. Regardless of the hard alloy or soft alloy ingot, the longitudinal and transverse mechanical properties are very different. Decreasing the casting temperature may cause sequential crystallization of the volume and degrade the mechanical properties.
3 Effect on crack tendency.
When other conditions remain unchanged, increasing the casting temperature, the liquid cavity becomes deeper, the columnar crystal formation tendency increases, the alloy's hot brittleness increases, and the crack tendency increases.
4 Effect on surface quality.
With the increase of the casting temperature, the wall of the solidified shell of the ingot becomes thinner. Under the action of the static pressure of the melt, defects such as pull marks, cracks, and the emergence of segregation matter are easy to form, but the tendency to form cold partitions is reduced.