Jul 16 2013
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
Machinability
Forming
Welding
Heat Treatment
Forging
Hot Working
Cold Working
Annealing
Tempering
Applications
Introduction
Water-hardening tool steels are also known as group W steels. This group consists of three types, namely, W1, W2, and W3. The main alloying element found in group W steels is carbon. To increase the wear resistance and hardenability of the W steels, a small amount of chromium can be added. By adding vanadium, the grain size is maintained, which enhances the toughness of the steels. The group W steels have low resistance to softening at high temperatures and are inexpensive.
The W1 steel is one of the most commonly available water hardening tool steel grades and can be easily hardened by heating and quenching in water. However, this alloy does undergo some amount of distortion during quenching. The following datasheet will provide details of W1 water-hardening tool steels.
Chemical Composition
The following table shows the chemical composition of W1 tools steels.
|
Element |
Content (%) |
|
C |
0.70-1.50 |
|
Mn |
0.10-0.40 |
|
Si |
0.10-0.40 |
|
Cr |
0.15 |
|
Ni |
0.2 |
|
Mo |
0.1 |
|
W |
0.15 |
|
V |
0.1 |
|
Cu |
0.2 |
|
P |
0.025 |
|
S |
0.025 |
Physical Properties
The physical properties of W1tool steels are outlined in the following table.
|
Properties |
Metric |
Imperial |
|
Density |
7.83 g/cm3 |
0.283 lb/in3 |
|
Melting point |
1435°C |
2615°F |
Mechanical Properties
The mechanical properties of W1 steels are tabulated below.
|
Properties |
Metric |
Imperial |
|
Tensile strength, ultimate |
1680 MPa |
244000 psi |
|
Tensile strength, yield |
1500 MPa |
218000 psi |
|
Poisson's ratio (25°C) |
0.27-0.30 |
0.27-0.30 |
|
Elongation at break |
3.50% |
3.50% |
|
Bulk modulus |
140 GPa |
20300 ksi |
|
Shear modulus |
80.0 GPa |
11600 ksi |
|
Elastic modulus |
190-210 GPa |
27557-30458 ksi |
|
Charpy impact, unnotched |
86.0 J |
63.4 ft-lb |
|
Hardness, Brinell (converted from Rockwell C Hardness) |
498 |
498 |
|
Hardness, Knoop (converted from Rockwell C Hardness) |
558 |
558 |
|
Hardness, Rockwell C |
50.0-51.0 |
50.0-51.0 |
|
Hardness, Vickers (converted from Rockwell C Hardness) |
531 |
531 |
|
Machinability (based on AISI 1212 steel as 100% machinability) |
40 |
40 |
Thermal Properties
The table below shows the thermal properties of W1 tool steels.
|
Properties |
Conditions |
|
T (ºC) |
Treatment |
|
Thermal expansion |
10.4 x 10-6/ºC |
20-100 |
- |
|
Thermal conductivity |
48.3 x W/mK |
100 |
- |
Other Designations
Other designations that are equivalent to AISI W1 tool steels include:
-
ASTM A686
-
SAE J437 (W108), (W109), (WhO), (W112)
-
SAE J438 (W108), (W109), (W110), (W112)
-
UNS T72301
Fabrication and Heat Treatment
Machinability
The machinability of W1 steels is very good as they are plain carbon steels with 100% rating based on which other tool steels are compared.
Forming
W1 steels can be easily formed using conventional methods.
Welding
W1 steels are weldable using all the standard methods.
Heat Treatment
The treatment depends upon the intricacy of the part or section size. W1 steels with large sections or intricate shapes have to be slowly preheated to 593°C (1100°F) and then the temperature should be slowly increased to 816°C (1500°F). The steels should be maintained at the same temperature for 10 to 30 minutes and finally water or brine quenched.
Forging
Forging of the W1 steels can be performed at 1038°C (1900°F) down to 816°C (1550°F) but not below 843°C (1500°F).
Hot Working
W1 steels can be hot-worked.
Cold Working
W1 steels in the annealed condition have very good ductility and can be easily cold worked using conventional methods.
Annealing
Annealing has to be performed at 760°C (1400°F) followed by slow furnace cooling at 4°C (40°F) per hour or less.
Tempering
Tempering of the W1 steels is performed at 177-343°C (350-650°F) to realize Rockwell C hardness of 64 to 50.
Applications
The W1 steels are mainly used for cold heading, hand-operated metal cutting tools, reamers and embossing taps. It is also used for cutlery.