Steels of optimal chemical composition combined with intensive quenching

Abstract

Manufacturing steels of optimal chemical composition, combined with intensive quenching, is an important step to save essential energy and make the environment cleaner. Historically, alloy and high alloy steels are hardened in oils or high concentration polymers to prevent crack formation during quenching. However, very slow cooling in oils requires more alloy elements to provide the needed surface hardness and hardenability. To extract expensive alloy elements from the ore one needs additional energy, plus, metallurgical processes are harmful to the environment. In this paper an idea on manufacturing and use steels of optimal chemical composition is discussed. Such steels produce an optimal hardened layer and optimal residual stress distribution in machine components after intensive quenching. Compressive residual stresses and high cooling rate within the martensite range result in additional strengthening of material. Both high compressive residual stresses at the surface of steel parts and additional strengthening (superstrengthening of the material) compensate for the decrease in alloy elements in the steel. Decreasing alloy elements saves essential energy and decreases environment pollution. The intensive quenching increases productivity and service life of steel parts. These important problems are widely discussed in the paper. Appropriate calculations are made and practical examples are provided.

Keywords:

• Optimisation
• Steel
• Compressive residual stress
• Superstrengthening
• Energy
• Environment
• Savings