Die Steels - Buderus Edelstahl Gmbh

The material concept
The right material for all
application profiles
Optimal use of a die steel is closely linked to understanding its stress
profile (Figure 1). The right die steel for forging-die and press-die
units and secondary tools is selected bearing in mind economic
and qualitative aspects. One major factor is the die’s service life
or estimated tool life quantity (see Tables 1 and on page 8). The
tool life quantity is generally limited by wear, or by cracking in the
case of complicated impressions (see Table 1 on page 8+9).
Die wear is significantly reduced as the alloy content of carbide
formers such as vanadium, molybdenum, tungsten and chromium
is increased, as shown in Figure . One qualitative measure of this
is the alloy coefficient (AC) used to rate steel. Higher-grade steels
produce favourable results when an optimum relationship between
tool life quantity and tool costs is achieved.
The tool life quantity can be further optimized by increasing hardness,
balanced with the necessary toughness characteristics. Key
here is uniform quenching and tempering of the dies throughout
their cross-section. Comparing the hardness distribution of the
standard die steel 2714 ISO-B to the recently developed new die
steel 2714ISO-Bmod. confirms this modified composition improves
hardening and tempering characteristics (see Figure and Table
on page 10).
Figure 1
Die tool stress profile
Mechanical
stress
Thermal
stress
Mechanically induced
state of tension
Mechanical die load
Relative movement
die/forging
Deformation • Cracking • Fracture
Wear • Deformation • Temperature fatigue cracking
Thermally induced
state of tension
Thermal die load
Loss of cohesion
Matched material characteristics
ensure high tool life quantities
This special steel is effective for forging dies with high volumes,
regardless of the die size and impression depth.
Heat resistance and hardness retention are key material indicators
for die steels. Loss of hardness and even transformation of the
microstructure at the impression surface is the most frequent cause
of wear, deformation and cracking.
Figure 2
Effect of alloy content on die wear
Die wear (µm)
µm
350
300
250
200
150
100
50
2713
2714
2744
2714mod.
2766
2343
2606
2365
2344
2367
Temperature 250°C
Alloy coefficient
2Cr + 5W + 10Mo + 40V
0
0 10 20 30 40 50 60 70 80 90 100 110 120
Alloy coefficient