Comparison of the secondary hardness effect after tempering of the hot-work tool steels

Purpose: of this paper was to examine of the secondary hardness effect after tempering of the developed complex hot-work tool steel 47CrMoWVTiCeZr16-26-8 in relation to standard hot-work tool steel X40CrMoV5-1. Design/methodology/approach: The investigations steels were made using the specimens made from the experimental steel, for which the working 47CrMoW-V-TiCe-Zr16-26-8 denotation was adopted, similar to the ones used in the ISO Standard on using the standard alloy hot-work tool steel X40CrMoV5-1. Both investigated steels were melted in a vacuum electric furnace. Specimens made from the investigated steels were heat treated with austenitizing in salt bath furnaces for 30 minutes in the temperature range of 970-1180 degrees centigrade with gradation of 30 degrees centigrade. Next, the specimens were tempered twice in the temperature range of 450-660 degrees centigrade for 2 hours. Findings: The secondary hardness effect after tempering from temperature of 540 degrees centigrade in the 47CrMoW-V-Ti-CeZr16-26-8 steel and from temperature of 510 degrees centigrade for the X40CrMoV5-1 steel, which is caused by the carbides M4C3 and M7C3 in the 47CrMoWVTiCeZr16-26-8 steel and M7C3 in the X40CrMoV5-1 steel. Practical implications: The developed complex hot-work tool steel 47CrMoWVTiCeZr16-26-8 can be used to the hot work small-size tools which requires higher strength properties at elevated temperature. Originality/value: The obtained results show the influence of the chemical compositions on the secondary hardness effect after tempering in the hot-work tool steel. The secondary hardness effect after tempering determined structure and mechanical properties in this kinds of steels group.