Annealing
Products | Solution annealing | Diffusion ann./homogenizing | Coarse grain annealing | Recrystallization annealing | Normalizing | Soft annealing | Stress relief annealing
Soft annealing
Soft annealing is carried out to
create pearlite, a soft microstructure which gives the best properties
for working metals without cutting, and for machining. It is done over
several hours directly below the Ac1 temperature. While the soft
annealing temperature for unalloyed steels can be taken directly from
the iron-carbon diagram, it is determined for alloyed steels according
to the following formula:
T W(°C) = 705 + 20 (% Si - % Mn + % Cr - % Mo - % Ni - % W) + 100 * % V
A special kind of soft annealing is spheroidizing (GKZ annealing)
during which a microstructure consisting of cementite grains in a
ferritic matrix is aimed at, and which gives the best working
properties.
The following Durferrit salts are very popular for soft annealing. GS 430 or GS 430/R2 for the temperature range of 700 - 800 °C, Durferrit GS 540 or GS 540/R2 for the temperature range of 700 - 950 °C, and Durferrit GS 660 or GS 660/R3, which do not contain barium, for the temperature range of 750 - 900 °C.
BG annealing
(annealing to obtain a certain microstructure for better processing)
consists of austenitizing, followed by rapid cooling, and isothermal
transformation in the temperature range of 650 - 690 °C. This
temperature is maintained until a complete transformation of the
microstructure has taken place. A microstructure, consisting of
lamellar pearlite and ferrite (steels with low and medium carbon
contents, and a low alloying content) is hereby produced in accordance
with the chemical composition of the steel, its transformational
behaviour, and the kind of cutting which follows. For higher alloyed
steels, and those with a higher carbon content, a microstructure with
granular cementite is aimed at. The isothermal transformation is
carried out after austenitizing in a separate salt bath.
Products used for
isothermal transformation
|
Woking temp. |
| Durferrit GS 430 |
500° - 700° C
|
| Durferrit GS 430/R2 |
700° - 800° C
|
| Durferrit GS 540 |
600° - 950° C
|
| Durferrit GS 540/R2 |
700° - 950° C |
(Please see product overview for details of products for austenitizing)
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Tel.: +49 (0) 621 32224-0, Fax: +49 (0) 621 32224-809
E-Mail: info@hef-durferrit.com
