Aug 20 2012
Topics Covered
IntroductionChemical
CompositionPhysical PropertiesMechanical PropertiesThermal PropertiesOther Designations
Introduction
Shock-resisting tool steels are designated as group S steels according to the
AISI classification system. S1, S2, S5, S6, and S7 are the members of
group S shock-resisting steels. The hardenability of group S steels can be controlled by
varying their composition instead of adjusting the melting procedures and grain
size. These steels can obtain optimum hardness at higher austenitizing
temperatures. The tempering resistance of group S steels can be enhanced by the
addition of silicon, which also forms a microstructure to resist distortion in
tempered conditions.
This article will give an overview of S5 shock-resisting tool steel.
Chemical Composition
The following table shows the chemical composition of S5 tool steels.
Element |
Content
(%) |
Iron, Fe |
95.0 |
Carbon, C |
0.50-0.65 |
Manganese, Mn |
0.60-1.00 |
Silicon, Si |
1.75-2.25 |
Chromium, Cr |
≤0.35 |
Molybdenum, Mo |
0.20-1.35 |
Vanadium, V |
≤0.35 |
Copper, Cu |
0.25 |
Phosphorus, P |
≤0.03 |
Sulfur, S |
≤0.03 |
Physical Properties
The physical properties of S5 tool steels are given in the following
table.
| Properties |
Metric |
Imperial |
| Density |
7.75 g/cc |
0.280 lb/in3 |
Mechanical Properties
The mechanical properties of S5 tool steels are tabulated below.
| Properties |
Metric |
Imperial |
| Hardness, Rockwell C (oil quenched from 816°C, 30 mins) |
50 |
50 |
| Hardness, Rockwell C (water quenched from 816°C, 30 mins) |
52 |
52 |
| Hardness, Rockwell C (oil quenched from 871°C, 30 mins) |
57 |
57 |
| Hardness, Rockwell C (water quenched from 871°C, 30 mins) |
59 |
59 |
| Hardness, Rockwell C (oil quenched from 954°C, 30 mins) |
61 |
61 |
| Hardness, Rockwell C (water quenched from 954°C, 30 mins) |
62 |
62 |
| Modulus of elasticity |
207 GPa |
30000 ksi |
| Charpy impact (V-notch; oil quenched from 927°C; 200°C temper
temperature) |
10.8 J |
8.00 ft-lb |
| Charpy impact (V-notch; oil quenched from 927°C; 600°C temper
temperature) |
20.3 J |
15.0 ft-lb |
| Machinability (1% carbon steel) |
65.0 - 70.0% |
65.0 - 70.0% |
| Poisson's ratio |
0.27-0.30 |
0.27-0.30 |
Thermal Properties
The following table shows the thermal properties of S5 tool steels.
| Properties |
Conditions |
| T
(°C) |
Treatment |
| Thermal expansion |
12.6 x 10-6/ºC |
20-425 |
- |
Other Designations
Other designations that are equivalent to S5 tool steels include:
- ASTM A681
- FED QQ-T-570
- SAE J437
- SAE J438
- UNS T41905