AISI A7 is a wear resistant tool steel. It is a chromium modified, air hardening tool steel that exhibits exceptional wear resistance. The High carbon and vanadium contents result in numerous, hard vanadium carbide particles in the steel.
» ASTM A681 (A-7)
» UNS T30107
CHEMICAL COMPOSITION
| C | Cr | SI | Mn | Mo | V | Ni | Cu | P | S | |
| Min | 2.00 | 5.00 | 0.15 | 0.20 | 0.90 | 3.90 | -- | 0.50 | -- | -- |
| Typical | 2.40 | 5.35 | 0.45 | 0.50 | 1.15 | 4.50 | 1.00 | -- | -- | |
| Max | 2.85 | 5.75 | 0.60 | 0.80 | 1.40 | 5.15 | 0.30 | 1.50 | 0.035 | 0.035 |
APPLICATIONS
- » Brick mould liners
- » sand slinger liners
- » extrusion tools for ceramics
- » Shot blasting equipment liners
- » powder compaction tooling
FORM SUPPLIED
- » Round bar
- » Plates
- » Flat Bar
Available surface conditions : hot rolled, ground, peeled, turned, drawn, cold rolled
HEAT TREATMENT
- Hardening: critical temperature 1340°F(727°C)
- Pre-Heating: heat at a rate not exceeding 400°F per hour to 1200-1300°F and equalize.
- Austenitizing: heat rapidly from preheat. Furnace or Salt:1700-1800°F. For maximum toughness use 1700°F, for maximum wear resistance use 1800°F. Soak at temperature for 15 minutes per inch of thickness at 30 minutes.
- Quenching: Air or pressurized gas, for air cooling, cool in still air to 150-125°F
- Tempering: temper immediately after quenching. Typical temperature is 300°F for maximum wear resistance.Hold at temperature for 4 hours then air
cool to ambient temperature. For maximum toughness, double temper, 2 hours plus 2 hours,at temperature above 900°F. - Annealing: Must be performed after hot working and before re-hardening. Heat at a rate not exceeding 400°F per hour to 1500-1550°F and hold at temperature for 1 hour per inch of thickness for minimum 2 hours.
Then cool slowly with the furnace at a rate not exceeding 50°F per hour to 1000°F. Continue cooling to ambient temperature in the furnace or in air.
| Tool | Hardening | Tempering |
| single edge cutting tools | 1220 ºC | 550-570 ºC |
| multi edge cutting tools | 1180-1220 ºC | 550-570 ºC |
| cold work tools | 1050-1150 ºC | 550-570 ºC |
PROCESSING
S1 can be worked as follows :
- Machining( grinding, turning, milling)
- Polishing
- Hot forming
- Electrical discharge machining
- Welding(special procedure incl. pre-heating & filler
materials of base material composition)
GRINDING
During Grinding, local heating of the surface, which can alter the temper, must be avoided. Grinding wheel manufacturers can provide advise on the choice of grinding wheels
SURFACE TREATMENT
The Steel Grade is a perfect substrate material for PVD coating. If nitriding is requested, a small diffusion zone is recommended but avoid compound and oxidized layers.
DELIVERY HARDNESS
» Typical soft annealed hardness is 255 HBW
» Cold drawn and cold rolled material is
typically 10-40 HB harder
