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Abstract

Casting technologies wllich improve casting yield and intenzal sOllndness of thin wall cast components are of particular interest to industry especially for critical applications. The main aim of fOll1ldries is to achieve castings free from defects at low cost. It hils been thought that pouring casting by side ingate technique improve directional solidification as the metal stays hot for long time in the feeder cum ingate. Experiments were carried alit IIsing a side gating technique to cast a number of 300 mm x 300 mm LMO and LM 25 plates in furall and pepset sand moulds. The thickness used was 5 and 10 mm for Juran and pepset sand mOlllds respectively. The plates were divided into sections lind tests carried out. The variation in plate thickness with temperature as well with bending stress and crack length was observed and recorded in plates made out of LMO materials. Tensile tests were carried out on LM 25 alloy and the relationship between pOllring temperature, pouring rate, plate thickness, and pOllring time with specimen location with respect to ingate in the casting was established. Plates poured at low rates but high temperature or vice versa give cOllsistent thickness val III'S. High pOllring temperature and pouring rates in sand moulds give uneven thickness along the plate casting. Thin castings poured by side gating technique showed a  tendency of cracking in a three point bending test, exhibited high strength scatter and severe porosity in the casting. Majority of the cracks were less than 3 mm in length.

Publisher Name

University of Dar es Salaam

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