The Effect of Forging Reduction on the Properties of a Die Steel

Abstract

The literature dealing with the effect of forging reduction
upon mechanical properties and service performance, with particular
reference to hot work steels, has been reviewed. The effect
of forging reduction on mechanical properties and the service
performance of BSS.224 No. 5. nickel-chromium-molybdenum hot
work die steel has been studied by processing a 34=ton electrically
melted ingot, forged in three stages, with forging reductions of
2.92, 9.0 and 18.5/1 respectively. From each bloom six die
inserts were manufactured to a hardness range of 363/388 B.H.N.
The life of the die inserts was compared with routine production
data. The effect of forging reduction on mechanical properties,
measured in three mutually perpendicular testing directions, was
investigated at room temperature.

The variation of properties is related to the distribution
and form of non-metallic inclusions, and not to heterogeneity
which, although apparently present on metallographic examination,
was not confirmed by chemical and micro-probe analyses. Even so
the micro hardness varied in a random manner. Increasing forging
reductions did not affect mechanical properties measured in the
longitudinal direction. Transverse and depth properties were
impaired by heavier amounts of forging, but not to the same extent that other workers have previously reported. Forging had no
influence upon die life except that heavy reduction minimised
scatter. Room temperature mechanical properties do not appear to
have a bearing on die life.

The published conversion tables of hardness and tensile
strength were found to be inapplicable to the range of hardness
studied.

Date of Award	1967
Original language	English