strength shows a marked reduction if tempering at about 300°C occurs.
Because of
this,
tempering should not be used at such temperatures. This also
has the effect that the impact strength resulting from slow cooling from a
higher tempering temperature is much lower than that when rapid cooling is
used. This effect is referred to as temper
brittleness.
It can be overcome by
adding a small amount of molybdenum, e.g. 0.3 per cent, to the alloy.
100
Ϊ 80
.5 60
c
O
g 40
3
-a
oi 20
0
1200
- 1000
-£800
c
T3
-Ϊ3 600
JZ
-1400
•c
03
- 200
0
^3
13
— >
1 — ■-
-
150
120
90
60
30
—
0
Impact strength
Rapid cooling
Impac
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