Methods to control macro shrinkage porosity and gas bubbles in cast aluminum engine blocks

摘要

A method for estimating proper eutectic modification level in a liquid metal to minimize macro shrinkage porosity and gas bubbles during casting of aluminum automobile components, and a system and article for casting.

主权项

1. A method of fabricating aluminum automobile components, by estimating proper eutectic modification level in a liquid metal to minimize macro shrinkage porosity and gas bubbles during aluminum casting, said estimating proper eutectic modification level comprising:
estimating the effective phosphorus level in the liquid metal using
Peff(wt %)=P(wt %)+c1*Sb(wt %)+c2*Bi(wt %)−c3*Ca(wt %)  (2); estimating the required minimal addition of strontium to the liquid metal using
Sreff-min(wt %)=a1+b1*Peff(wt %)  (3); estimating the allowed maximal addition of strontium to the liquid metal using
Sreff-max(wt %)=a2+b2*Peff(wt %)  (4); where: Peff (wt %) is the combined effect of trace elements on eutectic modification; P (wt %) is the phosphorous weight percent in the liquid metal; Sb (wt %) is the antimony weight percent in the liquid metal; Bi (wt %) is the bismuth weight percent in the liquid metal; Ca (wt %) is the calcium weight percent in the liquid metal; Sreff-min (wt %) is the required minimal addition of strontium in weight percent to the liquid metal eliminate macro shrinkage; Sreff-max (wt %) is the allowed maximal addition of strontium in weight percent to the liquid metal eliminate gas bubbles; and a1, a2, b1, b2, c1, c2, c3 are constants that depend on a given set of casting component geometry and casting process parameters; providing a mold; introducing the liquid metal into said mold such that porosity due to at least one of macro shrinkage and gas bubble formation is reduced; and cooling said liquid metal such that said liquid metal is substantially solidified.