Hardening / tempering

Hardening consists of heating the parts through to austenitizing temperature, followed by cooling, which must be done quickly enough to obtain the martensite and/or bainite which are characteristic of the hardened structure. The austenitizing temperature and speed of cooling are determined by the composition of the steel, and can be taken from the respective TTT diagrams. A uniform, and if possible, mono-phase microstructural consitution containing mostly dissolved carbon and/or fine precipitated carbides should be aimed for. The hardenability of a steel is clearly defined in the TTT diagrams. Hardening is followed by a further heat treatment, that is to say, tempering. If the tempering is carried out at above 350 °C, the process is no longer referred to as hardening and tempering, but to quenchhardening and tempering.

Salts for austenitizing

Durferrit produces salts for the austenitizing of unalloyed, low and high alloyed steels, and hot and cold work steels within a temperature range of 700 - 1100 °C. R2 and R3 inertors are added to the GS salts to ensure that decarburization does not take place during austenitizing. We supply special high temperature salts for the hardening of high speed steels (HSS) within a temperature of 1100 - 1300 °C. Decarburization does not take place when using these salts.

Non-inert produkts	Working temp.
Durferrit GS 660	750° - 900° C
Durferrit GS 670	750° - 1000° C
Durferrit GS 750	850° - 1100° C
Durferrit GS 960	1000° - 1300° C

Inert products	Working temp.
Durferrit GS 430/R2	700° - 800° C
Durferrit GS 540/R2	700° - 950° C
Durferrit GS 660/R3	750° - 900° C
Durferrit GS 670/R2	750° - 950° C
Durferrit GS 750/R2	900° - 1100° C
Durferrit GS 540/Semperneutral 950	900° - 1150° C

Products containing cyanide	Working temp.
Durferrit Cecontrol 50 H	780° - 950° C
Durferrit Cecontrol 80 B	800° - 950° C
Durferrit GS 540/C3 bzw.Cecontrol	600° - 900° C
Durferrit GS 560/C3 bzw.Cecontrol	580° - 950° C
Durferrit GS 660/C3 bzw.Cecontrol	700° - 1100° C
Durferrit GS 670/C3 bzw. Cecontrol	750° - 1150° C

Products for treating high speed steels	Working temp.
Durferrit Carboneutral	1000° - 1300° C
Durferrit Semperneutral 950	1100° - 1300° C
Durferrit Semperneutral 1100	1200° - 1300° C

There are many and varied possibilities of cooling /quenching heat treated parts. Depending upon the material, parts can be quenched in air, gas, oils/polymers, in water or in a martemper bath. In this connection, the martemper bath is the most flexible in use. Most grades of metal can be cooled in a martemper bath. The term martempering means cooling in a salt melt for the purpose of obtaining temperature equilibrium in the work piece prior to the formation of martensite. Martempering considerably reduces distortion, transfers heat uniformly and creates only a low level of thermal stress.

Products for martempering

Salts	Working temp.
Durferrit AS 140	180° - 550° C
Durferrit AS 220	250° - 550° C
Durferrit AS 235	280° - 550° C
Durferrit AS 300	340° - 550° C

Products for quenching / cooling

Quench water additives	Working temp.
Hydrodur	- 70° C
Hydrodur GF	- 70° C
Hydrodur 20	- 70° C
Hydrodur D	- 70° C

Salts for tempering

The term tempering means the heating through of a hardened work piece to a temperature below Ac1 and keeping it at this temperature, followed by cooling to obtain a certain microstructure.

AS salts are used for tempering within a temperature range of 180 - 550 °C and GS salts are used within a temperature range of 270 - 700 °C.

Products	Working temp.
Durferrit AS 140	180° - 550° C
Durferrit AS 220	250° - 550° C
Durferrit AS 235	280° - 550° C
Durferrit AS 300	340° - 550° C
Durferrit GS 230	270° - 500° C
Durferrit GS 430	500° - 700° C

 
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E-Mail: info@hef-durferrit.com