The use of zonal cooling to control the solidification rate of AK7ch alloy castings

Abstract

The aim of the work was to study the effect of zonal cooling, i. e., various coolants that accelerate heat removal on the solidification rate in local thickenings (sockets). In the work, standard methods were used to determine zonal cooling, solidification rate, and metal density. For the experiments, equipment was developed that allows filling prototypes from two metal ducts. As the alloy under study, AK7ch was used, as the most common for low-pressure casting. Copper liners and steel water-cooled liners were used as coolants for local thickenings. The density control of the obtained castings was carried out according to the hardness measured by the Brinell method.

The dependences of the influence of zonal cooling on the hardening rate of local thickening, which is determined by the density of the metal structure depending on cooling by both copper inserts and water, are revealed.

Ideas about the influence of zonal water cooling in low-pressure casting, on reducing the shrinkage loosens in the thickening of the casting and reducing the holding time of the metal under pressure were further developed.

The research results showed that the use of zonal cooling of local thickenings of the casting at all studied thicknesses increases the hardness index. The creation of directional solidification and reduction of the holding time of castings in the chill mold increase productivity, which also plays an important role in foundry.

Use of zonal water cooling for low-pressure casting of the "filter housing" part on the mod installation U95A allowed to eliminate shrinkage looseness in the local thickening and reduce the holding time of the casting under pressure, which in turn allowed to increase the productivity of the installation.