T1
Description
AISI/ASTM T1 tool steel is one of the original tungsten high speed steels, although all tungsten steel grades are used to a limited extent because of the cost and questionable availability of tungsten. Of the T group steels, the general purpose T1 tool steels and the high-vanadium-cobalt T15 are most commonly used. T1 high speed steel is an air or oil hardening tool steel which has good comprehensive performance. HSS T1 tool steel has a high hardness (HRC62~66), strength, toughness and heat resistance, which is an excellent cutting tool material. T-1 tool steel grade is on the whole used for turning, planning & slotting instruments, tapes, twist drill, threading dies, profile slicing instruments, broaching instruments & reamers.
Chemical Composition
| C | Si | Mn | P | Cr | V | W |
|---|---|---|---|---|---|---|
| 0.78 | 0.33 | 0.29 | 0.018 | 3.98 | 1.13 | 18.15 |
Standards
| AISI | JIS | DIN | BOHLER | HITACHI |
|---|---|---|---|---|
| T1 | SKH2 | 1.3355 | S200 | YHX2 |
Applications
Generally, high speed steels are used for machining at high speeds. HSS T1 steel materials are widely used for:
- Broaches
- Drills
- Hobs
- Knurling Tools
- Lathe Tools
- Milling Cutters
- Nut Piercers
- Planer Tools
- Reamers
- Shaving Tools
- Taps
- Thread Cutting Tools
| Properties | Metric | Imperial | |
|---|---|---|---|
| Density | 8.67 g/cm3 | 0.313 lb/in3 |
| Properties | Metric | Imperial |
|---|---|---|
| Hardness, Rockwell C | 63.0 – 65.0 | 63.0 – 65.0 |
| Poisson’s ratio | 0.27-0.30 | 0.27-0.30 |
| Elastic modulus | 190-210 GPa | 27557-30457 ksi |
| Properties | Conditions | ||
|---|---|---|---|
| T (°C) | Treatment | ||
| Thermal expansion | 9.7 x 10-6/ºC | 20-200 more | – |
| Thermal conductivity | 19.9 x W/m-K | 100 more | – |
| Treatment | Temperature Range | Cooling/Quenching | Notes |
|---|---|---|---|
| Forging | 1700-2100° F | Slow. | Cool slowly in dry sand or in other insulating media. |
| Annealing | 1600-1650° F | Cool slowly at a rate of 35° F per hour to 1000° F. | For best results, insulating media is desirable. Hold at temperature for 2 hours. |
| Stress Relieving | 1100-1300° F | Cool slowly | Stress relieve after rough machining |
| Preheating | 1500-1550° F | Preheat time in furnace is ¾ Hr. per inch of thickness. Heating up to temperature as slow as possible. | |
| Hardening | 2325-2375° F (furnace) | Quench in air or warm oil. To minimize quenching strains, quench in salt at 1000° F | For maximum wear resistance, harden at 2375° F. For maximum toughness and high hardness, harden at 2275° F. |
| 2275-2350° F (salt bath) | |||
| Tempering | 1022 ° F-1058 ° F | Temper T1 high-speed steel immediately after quenching. Hold for at least two hours | Double tempering is recommended. The usual tempering time is 2+2 hours. Recommended temperature is 1000-1075° F for cutting tools. 1100-1200° F for shock tools |
Soft Annealing
Heat to 820-8800 C, cool slowly in furnace. This will produce a maximum Brinell hardness of 230-300.
Stress Relieving
Stress relieving to remove machining stresses should be carried out by heating to 6500 C, holding for one hour at heat, followed by air cooling. This operation is performed to reduce distortion during heat treatment.
Hardening
Heat up to 450-6000 C, then preheat to 8500 C and to 10500 C. Harden from a temperature of 1250-12900 C followed by oil, air quenching or warm bath 5500 C. Hardness after quenching is 64-66 HRC.
Transformation temperatures: Ac1=8240 C, Ac3=8580 C.
Tempering
Tempering temperature: 3 x 1 hour at 550-5700 C
Tempering Temperature (0 C) vs. Hardness (HRC)
| 2000 C | 3000 C | 4000 C | 5000 C | 5250 C | 5500 C | 5750 C | 6000 C | 6500 C | 7000 C |
|---|---|---|---|---|---|---|---|---|---|
| 64 | 62 | 62 | 64 | 65 | 65.5 | 54.5 | 63 | 56 | 47 |
Tempering Diagram
