Jul 10 2013
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
Machinability
Forming
Welding
Heat Treatment
Forging
Cold Working
Annealing
Tempering
Applications
Introduction
Chromium hot-work tool steels are classified as group H steels by the AISI classification system. This series of steels start from H1 to H19.
H13 chromium hot-work steel is widely used in hot and cold work tooling applications. Due to its excellent combination of high toughness and fatigue resistance H13 is used more than any other tool steel in tooling applications.
This article will give an overview of H13 chromium hot-work steels.
Chemical Composition
The following table shows the chemical composition of H13 tool steels.
| Element |
Content (%) |
| Chromium, Cr |
4.75-5.50 |
| Molybdenum, Mo |
1.10-1.75 |
| Silicon, Si |
0.80-1.20 |
| Vanadium, V |
0.80-1.20 |
| Carbon, C |
0.32-0.45 |
| Nickel, Ni |
0.3 |
| Copper, Cu |
0.25 |
| Manganese, Mn |
0.20-0.50 |
| Phosphorus, P |
0.03 |
| Sulfur, S |
0.03 |
Physical Properties
The physical properties of H13 tool steels are given in the following table.
| Properties |
Metric |
Imperial |
| Density (@20°C/68°F) |
7.80 g/cm3 |
0.282 lb/in3 |
| Melting point |
1427°C |
2600°F |
Mechanical Properties
The mechanical properties of H13 tool steels are tabulated below.
| Properties |
Metric |
Imperial |
| Tensile strength, ultimate (@20°C/68°F, varies with heat treatment) |
1200 - 1590 MPa |
174000 - 231000 psi |
| Tensile strength, yield (@20°C/68°F, varies with heat treatment) |
1000 - 1380 MPa |
145000 - 200000 psi |
| Reduction of area (@20°C/68°F) |
50.00% |
50.00% |
| Modulus of elasticity (@20°C/68°F) |
215 GPa |
31200 ksi |
| Poisson's ratio |
0.27-0.30 |
0.27-0.30 |
Thermal Properties
The following table shows the thermal properties of H13 tool steels.
| Properties |
Conditions |
| T (ºC) |
Treatment |
| Thermal expansion |
10.4 x 10-6/ºC |
20-100 |
- |
| Thermal conductivity |
28.6 W/mK |
215 |
- |
Other Designations
Other designations that are equivalent to H13 tool steels include:
- AFNOR Z 40 COV 5
- DIN 1.2344
- UNI KU
- JIS SKD61
- SS 2242
- B.S. BH 13
- ASTM A681
- FED QQ-T-570
- SAE J437
- SAE J438
- SAE J467
- UNS T20813
- AMS 6408
Fabrication and Heat Treatment
Machinability
The machinability rate of H13 tool steels is nearly 75% of that of the W group tool steels.
Forming
H13 tool steels are formed by using conventional methods.
Welding
H13 tool steels are readily weldable.
Heat Treatment
H13 tool steels are preheated to 816°C (1500°F). Then the steels are directly heated by increasing the temperature to 1010°C (1850°F) followed by holding for 15 to 40 mins. The steels are then air-quenched.
Forging
H13 tool steels are forged at 1079°C (1975°F). For this type of steels, forging below 898°C (1650°F) is not preferable.
Cold Working
Cold working may be carried out on H13 tool steels using conventional methods.
Annealing
H13 tool steels are annealed at 871°C (1600°F) and slowly cooled at 4°C (40°F) in the furnace.
Tempering
Tempering is carried out in H13 tool steels from 538 to 649°C (1000 to 1200°F) to obtain Rockwell C hardness of 53 to 38. Double tempering can also be performed in these steels for every one hour at the preferred tempering temperature.
Applications
H13 tool steels are suitable for forming extrusion dies.