Tool steels that require high dimensional stability should be aged after hardening or returning. As a result of aging, much of the remaining austenite change into mathnosite. After the aging of the steel, the dimensions of the steel remain stable, which means that its dimensions will not change any more.
In the natural aging method, the work piece is kept in storage for several months, and since this method is not economical, the artificial aging is used. Artificial aging is carried out as follows:
Thermal aging is at temperatures of 100-120 ° C in an oil bath or hot air furnace, depending on its dimensions, for 20-60 hours.
– Fluctuating aging at 100 ° C in an oil bath or hot air furnace for 2-4 hours. Cooling in brine at -5 ° C. This process is repeated several times.
Low temperature aging at -80 ° C to -100 ° C. Low temperature cooling operation is carried out in special equipment and reservoirs. For low-temperature cooling, dry ice materials (from -55 ° C to -60 ° C), dry ice-alcohol mixtures (about -80 ° C), liquid air (-191 ° C), liquid oxygen (-183 ° C) Celsius) and liquid nitrogen (-196 degrees Celsius) are used. After all sections of the work piece have cooled down, depending on the defective parameters, it takes about 10 to 20 minutes, the return operation must always be done. For this, it is best to heat the work piece for a short time to 100 degrees Celsius.
Vibration aging. This method takes place at ambient temperature with the help of fluctuations and lasts about 30 minutes.
Aging of orders, measuring components and precision components will result in high stability – dimensional and – form. In molds, it increases hardness and uniform hardness.
Heat treatment of tool steel:
In molding, non-alloy tool steels, cold work steels and hot work steels are more widely used. High-speed steels are rarely used in molding.
Non-alloy tool steels:
In non-alloy steel, its carbon content indicates its properties. The amount of carbon in these steels is 0.45-1.5 degrees Celsius. These steels are often hardened with water. Its hardening depth is about 2-5 mm.
The soft annealing temperature is 680-710 ° C. The return is depending on the application target between 180 ° C and 300 ° C. The hardness and abrasion resistance of these steels will remain stable only up to 250 ° C.
table1: Thermal treatment of non-alloy tools
|Practical examples in molding||Hardness depth mm||Hardness|
|Cooling materials(quench)||Hardness temperature||Hardness after soft annealing|
|Short name according to|
|Cutting molds, Prissy punches||2,0…3,0||65||water||770…800||190||C 105 W1||1.1545|
|Cutting molds||3,5…5,0||58||water||800…830||190||C 45 W||1.1730|
|Hot working mold, stretch punches||3,5…5,0||62||oil||790…820||217||C 75 W||1.1750|
|Deep hole forging molds||2,0…3,5||60||water||790…820||170||C 55 W||1.820|
Cold work steels:
Regarding the cold work steels thermal treatment instructions, it is very helpful to take into consideration the manufacturer’s recommendations (Table 2).
Soft annealing, hardening and return temperature depend heavily on its alloying elements and are therefore very different. The cold work steel with the material number 1.2436 at a return temperature of 100 ° C, hardness of 64 HRC, at a return temperature of 200 ° C, will have a hardness of 83 HRC, and at a temperature of 300 ° C, a hardness of 60 HRC.
The hardness of the high-speed steel with the material number 1.3247 after the return is greater than its hardness after the quenching. In addition, in the case of this steel, first of all, it takes up to 400-600 ° C, then in the initial preheating up to 850 ° C and in the preheat secondary to 1050 ° C, and its hardening at a temperature between 1180 and 1210 ° C The temperatures and maintenance periods should be strictly observed.
Table 2 : Heat treatment of cold work steels
|Hardness after quenching||Quench material||Hardening temperature|
|Hardness after soft annealing|
|Characteristic according to DIN 17006||Material number|
|300…150||65||روغن||830...800||211||720...680||85 Cr 1||1.2004|
|300…150||58||روغن||1050...1020||225||800..750||X 42 Cr 13||1.2083|
|250...180||64||روغن، هوا||980...930||239||830...800||X 210 CrW 12||1.2436|
|350...180||56||روغن||860...830||238||700...660||45 NiCr 6 V||1.2710|
|300...160||59||روغن، هوا||870...840||217||630...610||50 NiCr 13||1.2721|
|250...150||64||روغن||820...760||211||720...690||90 MnCrV B||1.2842
|540...510||67||روغن، هوا||1210...1180||–||820...770||S 2-10-1-8||1.3247|
Hot work steels:
The heat treatment instructions of the hot working steels, especially its alloy types, are particularly useful for keeping the heating time and storage time accurate. The hardness of these steels depends on the temperature of the return. For example, steel mold forging with material number 1.2713 at return temperatures below has different strength values. (Table 1)
Table 1:Relationship between strength and return temperature (for steel, 1.273)
|Hardness with strength after quenching||Quench material||Hardening temperature|
|Hardness after soft annealing|
|Soft annealing temperature|
|Short characteristic according to DIN 17006||Material number|
|500...400||58 HRC||water||820...790||190||710...680||C 45 W||1.1730|
|650...550||2060 N/mm2||oil||1000...950||219||770...740||48 CrMoV 6 7||1.2323|
|650...550||1960 N/mm2||oil، air||1050...1020||235||780...760||X 38 CrMoV 5 1||1.2343|
|670...550||1720 N/mm2||oil، air||1050...1020||230||780...760||X 32 CrMoV 3 3||1.2365|
|650...500||1860 N/mm2||oil||870...840||240||710...680||55 NiCrMoV 6||1.2713|