Steel Casting with Insufficient Strength Properties

In a steel foundry, tensile and bend specimens of castings made in a 2-ton basic arc furnace showed, at irregular intervals, regions with coarse-grained fractures where the specimens broke prematurely, so that the specified strength and toughness values could not be reached. Several cast tensile specimens and some forcibly-broken pieces of the flanges of armature yokes made of cast steel GS C 25 according to DIN 17 245 were investigated. Microscopic examination showed that the cause of damage was the superabundant use of aluminum as deoxidizer. According to recommendations, the aluminum addition was reduced by one-half. Since then, there have been no additional rejects due to insufficient tensile and bend values.