Tempering of the holding time after different temperature of clad steel plate for saw blade steel has been carried out

the hardness of cladding plate and hase plate and the microstructure evolution are measured and observed. The results show that the lath martensite in substrate steel Q345 coarsens gradually during tempering

but the characteristics of lath can be retained after tempering at higher temperatures. However

the acicular martensite in cladding plate steel 45Mn2V degrades faster than that in substrate steel

so the characteristics of acicular could not be observed after tempering at 400℃ .

which results in the decreasing of hardness of cladding plate steel 45Mn2V after tempering is larger than that of substrate steel Q345. Therefore

the tempering temperature of the clad plate should not exceed 400℃. On the other hand

because of the high carbon content

the precipitation of carbides in steel 45Mn2V cladding plate is faster and more during tempering

so high hardness can still be maintained after tempering for 8 hours

while the Q345 substrate plate has obviously softened. Therefore

the optimum performace of steel can be got by oil quenching at 860 ℃ for 5 min and tempering at 360 ~ 390℃  for 6 h.