Electroslag Remelted tool steel for cold and hot work applications where high strength and hardness are combined with high toughness
SNAPPER ESR is a special alloyed Cr-Mo-V steel, secondarily hardenable, with very high toughness, good compressive strength, high wear resistance also at high temperatures.
Applications
SNAPPER ESR can be used for hot working applications as hot stamping dies, press hardening dies for direct and indirect methods. SNAPPER ESR is recommended for high demanding applications.
SNAPPER ESR can be used for all cold working applications requiring a combination of high hardness and toughness as in automotive and white goods industries. SNAPPER ESR is recommended for high demanding applications.
SNAPPER ESR can be used for industrial knives and it is especially suitable for use as chipping knives and all industrial knives such as those in the paper and wood industry and also for knives for cutting metals thicker than 5 mm and up to 15 mm.
Main properties
- Excellent wear resistance even at high temperatures
- Excellent toughness
- Good compressive strength
- High hardenability
Chemical composition (typical)
| C | Mn | Si | P | S | Cr | Mo | V |
|---|---|---|---|---|---|---|---|
| 0.47 | 0.50 | 0.30 | ≤ 0.02 | ≤ 0.003 | 7.50 | 1.50 | 1.40 |
Designation
| Werkstoff Nr | ISO | China GB | JIS Japan | UK | AISI USA | Russia Gost | AFNOR | Other / Special |
|---|---|---|---|---|---|---|---|---|
| 1.2360 mod | X48CrMoV8-1-1 mod | Cr8Mo2SiV | – | – | – | – | – | – |
Structure
Because of the moderate carbon content and the medium chromium content the structure of the SNAPPER ESR is fine and homogeneous without precipitation or alignments of carbides.
SNAPPER ESR which is an electroslag remelted steel (ESR) is very high and according to ASTM E 45 – 95 method A it is at most equal to: fine series: A0.5 – B0.5 – C0 – D1.5 / thick: A0.5 – B0.5 – C0 – D1 with B + C + D ≤2.5
Such level of cleanliness leads to an improved fatigue life of the SNAPPER ESR.
Hardness at the time of delivery
Annealed for 250 HB max.
Physical properties
| Temperature | 20°C | 200°C | 400°C |
|---|---|---|---|
| Volumic mass kg/m³ | 7800 | 7750 | 7700 |
| Young Modulus N/mm² | 210000 | 200000 | 188000 |
| Thermal conductivity W/m.K | 26 | 24 | 27 |
| Coefficient of linear expansion 10-6/K | 11.5 | 11.9 | 12.5 |
Heat treatment
Soft annealing
Temperature: 820 – 850°C, duration 1h + 1h for 25 mm thickness. Slow cooling in the furnace (10 to 20°C/h). The atmosphere in the furnace must be reducing to avoid decarburization of the steel.
Stress relieving
After machining, it is recommended to perform stress relieving at 650°C for a minimum of 2 hours, followed by slow cooling in the furnace to 450°C.
Austenitization
In order to avoid any risk of cracking it is recommended to preheat in 2 steps.
- 1st preheating step: temperature: 600°C time: 30 s/mm of thickness
- 2nd preheating step: temperature: 850°C time: 30 s/mm of thickness
Recommended austenitizing temperature: 1030 – 1090°C. The holding time should not be too long to avoid a risk of grain coarsening and a loss of toughness. It is recommended to keep the part at the austenitizing temperature 30 minutes per inch of thickness as soon as the temperature of the surface reach the austenitization temperature.
Sub zero treatment
For parts used in cold work applications that need to have high dimensional stability and to increase wear resistance without reducing toughness, it is recommended to perform a subzero treatment at a temperature between -70°C and -190°C for 1 hour for 25 mm of thickness of the part.
The temperature range from -70°C up to -120°C (named cold treatment of steel) leads to the complete transformation of austenite into martensite and as consequence to better stability associated with improved hardness and better wear resistance and the temperature range from -135°C down to -190°C (named cryotreatment of steel) leads also to the complete transformation of austenite and also the precipitation of ultrafine carbides improving a lot the wear resistance without modification of the toughness.
This treatment is optional for common applications.
Quenching medium
Oil at 80°C, vacuum (pressure > 6 bars), salt bath 500 – 550°C.
To ensure good toughness, treatment with oil or salt bath is preferable.
The hardness after quenching is 54 to 56 HRC.
Tempering
To ensure a minimum residual austenite rate as well as greater tool stability, it is essential to perform a double tempering. Each tempering is followed by a cooling under 100°C.
Each tempering time must be at least equal to 1h + 1h for 25 mm of thickness of the treated part (equivalent thermal thickness).
Surface treatment
Nitriding
SNAPPER ESR is not recommended to be nitrided since the nitriding temperature of the SNAPPER ESR is quite low.
PVD, CVD
SNAPPER ESR is suitable for all kind of PVD and CVD treatment as soon as the treatment temperature is 30°C lower than the last tempering temperature.
Machining
The machining parameters below are given for information only and must be adapted according to the equipment and usual machining conditions.
Turning
| Carbide tool Rough machining |
Carbide tool Finishing |
HSS tool Finishing |
|
|---|---|---|---|
| Cutting speed m/min | 130 – 170 | 170 – 220 | 17 – 22 |
| Feed mm/r | 0.15 – 0.3 | 0.1 – 0.15 | 0.1 – 0.3 |
| Depth of cut mm | 2 – 3 | 0.5 – 1.5 | 0.5 – 2 |
Milling: surfacing
| Milling with carbide tools Rough machining |
Milling with carbide tools ½ Finishing |
Solid tool Finishing |
|
|---|---|---|---|
| Cutting speed m/min | 160 – 180 | 180 – 200 | 210 – 280 |
| Feed mm/r | 0.40 | 0.4 – 0.35 | 0.10 – 0.05 |
| Depth of cut mm | 1 – 2.5 | 1 – 1.5 | 1 – 0.5 |
Drilling: HSS twist drill
| Drill diameter mm | Cutting speed m/min | Feed mm/t |
|---|---|---|
| < 5 | 13 – 15 | 0.05 – 0.15 |
| 5 – 10 | 13 – 15 | 0.15 – 0.20 |
| 10 – 15 | 13 – 15 | 0.20 – 0.25 |
| 15 – 20 | 13 – 15 | 0.25 – 0.30 |
Drilling: carbide drill
| Carbide type | Indexable insert | Solid carbid | Carbide tip |
|---|---|---|---|
| Cutting speed m/min | 160 – 180 | 100 – 130 | 55 – 80 |
| Feed mm/t | 0.05 – 0.10 | 0.10 – 0.25 | 0.15 – 0.25 |
Fine grinding
General indications for grinding wheels to be used on SNAPPER ESR in the heat treated condition
Usually, rather soft vitrified aluminum oxide grinding wheels (grades G for plane grinding to K for cylindrical grinding) are used.
Particular attention will be paid to effective cooling of the surface during grinding to prevent degradation of the material surface.
Electro-discharge machining
SNAPPER ESR is also suitable for EDM machining (wire or electrode). Preferably, the machining will be carried out with a low current density and a high frequency in order to limit the thickness of the white layer as much as possible.
Then it is necessary to carry out a stress relieving at 25°C below the last tempering in order to reduce the level of residual stresses (which could lead to a risk of cracking) and to carry out a polishing to completely remove the white layer formed during the discharge machining process.
Welding
It is not recommended to weld SNAPPER ESR but if this is mandatory it could be welded in the heat treated condition.
- Method: TIG
- Feeder wire: UTP 67 (56 HRC) or UTP 69 (62 HRC)
- Preheating: 250°C. Hold at 200°C during the welding operation with a maximum interpass temperature at 350°C. Slow cooling (max 20°C/h) after welding.
- Post treatment: tempering at 20°C below the last tempering temperature with a tempering time at least equal to 1h + 1h for 25 mm of thickness of the treated part (equivalent thermal thickness).
Download the TGX SNAPPER ESR datasheet (PDF)
More grades: Cold Work Tool Steels. Where to buy: Service Network.
