Abstract
The authors have treated hardenability in this paper in welding of medium and high carbon machine structural steels without and with Cr, Mo and Ni low alloy elements using Gleeble machine.
Then a new equation for estimating HAZ hardness is introduced, using the concept of Δt8/3 parameter and carbon equivalent. Moreover, the new equation has been confirmed for the reliability by many data measured. Therefore, the estimation for HAZ hardness is possible for the steels whose carbon content is more than 0.3%.