抄録
According to the industrial progress, it is evident that the demand is going up to get large steel mass having the great stiffness and toughness. This problem will be solved by using some alloy steels in spite of plain carbon steel. To have good alloy steel it is necessary that the large mass is thoroughly uniform.
Some special properties of alloy steels are investigated and described here.
1) Mass effect;: -Steels used are plain C-steel, Ni-steel, Cr-steel, Ni-Cr-steel, Ni-Cr-mo steel, long rods of various diameters are forged from ingots, Annealed and quenched in water and in oil from hardening temperature. Hardeness change through the sectional area is measured, Theoretical interpretation is made on the phenomene of mass effect, concerning to the chemical composition, cooling velocity and the mass,
2) Residual stresss due to heat treatment;: -Several methods to measure the internal stress are described, Some experiments are made to research the residual stress due to heat treatment in using large mass of alloy steels, Some methods to eliminate the residual stress are discussed,
3) Temper-brittleness;: -The phenomene of temper-brittleness is described, To ascertain the relation between the temper-brittleness and tempering temperature, some experiments are made,
Conclusion;: -To have good alloy steels of large mass, it is necessary to select the steel without or least mass effect. To avoid the effect of residual stress due to tempering, it must be reheated to a high temperature for some hours, but the temperature must be selected that no temper-brittleness well occur.
