1955 Volume 41 Issue 1 Pages 23-31
The effects of alloying elements on Charpy U notch impact properties were investigated in the range from room temperature to 900°C. Arsenic, copper, tin and molybdenum were added singly or simultaneously to a base composition of 0.04% carbon, 0.2% silicon and 0.4% manganese. Ferrite and austenite grain sizes, hardness and microscopic structures of the specimens were also examined. The results obtained are as follows:
1) Copper less than 0.35% or tin less than 0.1% has no effect on impact property of dcad soft steel when either of these is added to the steel.
2) When copper and tin are added together to a steel, the temperatures in which the impact value becomes maxiinum and minimum respectively move to higher temperature range.
3) When arsenic, copper and tin are added together to a steel, transition temperature of the steel is increased as the content of arsenic increases. Whcn a steel contains less than O.25% arsenic, 0.35% copper and O.1% tin, any serious effect is not observed on impact properties at room temperature and these values may be the maximum limit of the allowable content.
4) Molybdenum has the tendency to lower impact value at room temperature, inhibits the decrease of minimum impact value in blue shortness range and also inhibits the temperature of maximum impact value to move to higher temperature range.
5) Ferrite and austenite grains are fine and neary similar in all specimens, but ferrite grains of the specimens which showed brittle fractures at room temperature are somewhat larger than the others.
6) Hardness of annealed specimens increases as the content of arsenic, copper, tin and molybdenum increases.
7) From the results obtained above, the maximum allowable content of arsenic, copper and tin are estimated for the deformability of dead soft steel. The form of ingots, heating temperature and its time etc. must also be considered for the determination of the allowable limit.