Internal friction investigation on thermal-stability of martensitic hot work tool steel

Kinetics of thermal aging of two martenistic hot work tool steels were investigated by JMA equation and measurements of elastic modulus and internal friction.The results indicate that the recovery of martensite phase leads to the softening in 4Cr2Mo2W2MnV steel during the initial stage of high temperature aging.Desolution of W and V atoms from the matrix and precipitation of carbides result in the sharp decrease of mechanical properties of 3Cr2W8V steel aged at 620 ℃.The 4Cr2Mo2W2MnV steel has better thermal stability compared with 3Cr2W8V steel.Mn element and(Mo,V)C carbides in the matrix is responsible for the better thermal stability of 4Cr2Mo2W2MnV steel.