AISI T4 high speed tool steel manufacturers and suppliers, supplied in round bar,square bar,flat bar,plate,sheet and wire.AISI T4 Tool Steel is one of tungsten type high speed tool steel according to ASTM/A600 standard. Compared with AISI T1 , the composition is very similar,but T4 has additional 5% Cobalt which improves the high temperature hardness and red hardness.T4 can be hardened with hardness 66-70HRC.
1.Supply Form & Size & Tolerance
| Round bar | ||||
| Diameter | 1-16mm | 10-50mm | 50-180mm | 180-300mm |
| Process | Cold Drawn | Hot Rolled | Hot Forged | Free Forging |
| Flat bar | ||||
| Thickness | 1-2.5mm | 1.5-20mm | 20-300mm | |
| Width | Max 800mm | Max 800mm | Max 800mm | |
| Process | Cold Drawn | Hot Rolled | Hot Forged | |
Remark:Tolerance can be customized as per requests
2.Chemical Composition
| Standard | Grade | C | Mn | P | S | Si | Cr | V | Mo | W | Co |
| ASTM A600 | T4 | 0.70-0.80 | 0.1-0.4 | 0.03 | 0.03 | 0.2-0.4 | 3.75-4.5 | 0.8-1.2 | 0.4-1.0 | 17.5-19.0 | 4.25-5.75 |
| DIN EN ISO 4957 | 1.3255 | 0.75-0.83 | 0.4 | 0.03 | 0.03 | 0.45 | 3.80-4.5 | 0.8-1.2 | 0.5-0.8 | 17.5-18.5 | 4.50-5.50 |
| JIS G4403 | SKH3 | 0.73-0.83 | 0.4 | 0.03 | 0.03 | 0.45 | 3.80-4.5 | 0.8-1.2 | — | 17.0-19.0 | 4.50-5.50 |
3.Physical Property
| Density, g/cm3 | 8.68 |
| Melting point,°C | 1432 |
| Thermal conductivity, W/m.K | 19 |
| Electric resistivity,Ohm mm2/m | 0.65 |
| Specific heat capacity,J/g.K | 0.46 |
| Thermal expansion co-efficient,µm/m°C | 11.9 |
4. Mechanical Property
| Modulus of elasticity | 190-210 GPa |
| Poisson’s ratio | 0.27-0.30 |
5.Forging
Pre heat the AISI T4 with two steps.First,heat slowly and uniformly to 860-900°C with a rate not exceeding 220°C per hour,second,heat more quickly to the forging temperature of 1050-1150°C.Re-heating is necessary when temperature below 900°C. Slow cooling in furnace after forging.
6.Annealing
Annealing must be performed after hot working and before re-hardening.Heat the temperature to 820 to 850°C with a rate not exceeding 220°C per hour.Controlled slow cooling in furnace at 10 to 20°C per hour to approximately 550°C, followed by cooling in still air. Hardness after annealing 265 Brinell, maximum.
7.Stress Relieving
It is recommended to stress relieve after machining and prior to hardening to minimise the possibility of distortion.Heat in a neutral atmosphere to the temperature of 600 to 650°C, and soak for approximately two hours,followed by slow cooling in the furnace.
8.Hardening
Preheat AISI T4 steel slowly to the temperature of 820-870°C,then heat T4 uniformly to the temperature 1260-1290oC ,followed by oil, air quenching or warm bath at 550oC.
9.Tempering
Tempering should be carried out immediately after quenching. Heat slowly and uniformly to the tempering temperature 560-580oC,soak well not less than 2 hours(one hour per 25mm of total thickness).Double tempering is recommended,hardness after tempering is 64-65 HRC.
10.Application
AISI T4 high speed steel is widely used to make various cutting tools of higher temperature.
Typical use include:turning tool,cutter,reamer,forming cutting tools,drilling tools,broaches and cold extrusion punches, planing and milling cutters for roughing work.
