Core reaction and porosity formation study with Haynes 282

Purpose and goal:

This project aims to investigate the core-metal reaction and porosity in cast Haynes 282 component using alternative core materials or core coatings. Because the results of this project were mostly inconclusive it is suggested that further investigation is required. Expected results and effects:

It is inconclusive if microporosity formation is affected by the choice of core material. There is a tendency that parts casted with cores coated with alumina to present more severe micro-porosity problems.

Reaction surface layers were observed only in parts the underwent HIP or heat-treatment. This indicates that the core material plays no role in the formation of a reaction layer. It is theorized that the parts were exposed to atmospheric oxygen and nitrogen during HIP or Heat-treatment resulting in the formation of an oxide-nitride layer on the surface of the castings.

Approach and implementation:

During the run of the project four different investment casting trials were performed using a variety of core materials. Shell manufacturing and casting was performed according to TPC´s industrial standards for investment casting.

The prepared samples were examined for micro-porosity and evidence of chemical reractions using Fluorescent Penetrant Investigation and OES microscopy.