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





Generally, high speed steels are used for machining at high speeds. HSS T1 steel materials are widely used for:

  1. Broaches
  2. Drills
  3. Hobs
  4. Knurling Tools
  5. Lathe Tools
  6. Milling Cutters
  7. Nut Piercers
  8. Planer Tools
  9. Reamers
  10. Shaving Tools
  11. Taps
  12. Thread Cutting Tools
Density8.67 g/cm30.313 lb/in3
Hardness, Rockwell C63.0 – 65.063.0 – 65.0
Poisson’s ratio0.27-0.300.27-0.30
Elastic modulus190-210 GPa27557-30457 ksi
T (°C)Treatment
Thermal expansion9.7 x 10-6/ºC20-200 more
Thermal conductivity19.9 x W/m-K100 more
TreatmentTemperature RangeCooling/QuenchingNotes
Forging1700-2100° FSlow.Cool slowly in dry sand or in other insulating media.
Annealing1600-1650° FCool 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 Relieving1100-1300° FCool slowlyStress relieve after rough machining
Preheating1500-1550° FPreheat time in furnace is ¾ Hr. per inch of thickness. Heating up to temperature as slow as possible.
Hardening2325-2375° F (furnace)Quench in air or warm oil. To minimize quenching strains, quench in salt at 1000° FFor maximum wear resistance, harden at 2375° F. For maximum toughness and high hardness, harden at 2275° F.
2275-2350° F (salt bath)
Tempering1022 ° F-1058 ° FTemper T1 high-speed steel immediately after quenching. Hold for at least two hoursDouble 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.


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 temperature: 3 x 1 hour at 550-5700 C

Tempering Temperature (0 C) vs. Hardness (HRC)

2000 C3000 C4000 C5000 C5250 C5500 C5750 C6000 C6500 C7000 C

Tempering Diagram