Abstract

Effect of partial heat treatment on the mechanical properties of high carbon tool steel used in manufacturing active parts in cold work tool steel dies was investigated in this work. High carbon alloy steel (X210Cr12) classified as
(QN1.2080) according to (DIN) was used for machining specimens with
dimensions (5×44×20mm).
(18) specimens were insulated from the middle to the end by graphite with (5mm)
thickness and (18) specimens were insulated by ceramic (Al2O3 + Kaolin) with
(5mm) thickness. The distance between the middle to the sharp edge was not
insulated. All these specimen were subjected to heat treatment, They show that can
obtain hardness (65HRC) for the sharp edge at (980oC) after the specimens were
quenched in oil. Stress relive was subjected to all specimens , it has been shown
during heating between (100-200oC) There is no big effect on the hardness and the
strength was increased, also when heating temperature increase up to (600 C ) the
hardness decrease at (30 HRC) .
Rockwell hardness test was employed to all specimens, at four locations
for each specimen. The first location is at distance (10mm) from the sharp edge and
the second at (20mm) from the sharp edge within un insulated part. The third
location is at (30mm) and the forth at (40mm) from the sharp edge within
insulated part.
The best values of hardness for the insulated specimen with graphite are
(65,64HRC) within the un insulated part and (47,48 HRC) within the insulated
part. For the specimen with ceramic insulation the hardness values are (65,64
HRC) within the un insulated part and (51,52 HRC) within the insulated part.
The results of this work was applied on the active parts of some press
working sheet metal dies, produced in central tool room plant/Nasser state
company, it has been shown that the life and fracture strength of these parts (punch,
die and stripper) were increased and improved.