Optimum Carbon Content for Tempered Martensitic Steels

Notch-tensile tests were conducted on four quenched and tempered steels to study the effect of carbon content on notch toughness. The toughness was found to decrease when the carbon content was either above or below an optimum value of about 0.35 to 0.40 percent. The general engineering concept which prefers a low-carbon steel to a high-carbon steel for better toughness is briefly discussed in view of the present and previous experimental results.