Introduction of S5:
S5 Shock-Resisting Tool Steel is a silicon-manganese tool steel which exhibits the highest impact toughness among all of the “S” type steels. The high toughness and the ability to be hardened to 62 Rockwell C make S5 an excellent choice for applications that require higher strength than S7 shock-resisting tool steel. The steel is typically hardened using an oil quench, but for simple geometries, the steel may be water quenched.
APPLICATIONS of S5:
Shock-resisting tool steels are designated as group S steels according to the AISI classification system. S1, S2, S5, S6, and S7 are the types of shock-resisting tool 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 addition of silicon, which also forms a microstructure to resist distortion in tempered conditions.
S5 Tool Steel Chemical Composition:
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
S5 Tool Steel Mechanical Properties:
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
AISI S5 Tool Steel Heat Treatment:
HARDENING
Critical Temperature:
Ac1: 1410°F (766°C)
Preheating: Heat at a rate not exceeding 400°F per hour (222°C per hour). For complex and large tools, heat to 1150-1250°F (621-677°C) and equalize. Then heat to 1300-1400°F (704-760°C) and equalize. For simple geometries, use only the second preheating temperature range.
Austenitizing (High Heat): Heat slowly from the preheat. For Oil Quenching: 1600 - 1700°F (871 - 927°C) For Water Quenching: 1550 - 1650°F (842 - 899°C) Soak for 30 minutes for the first inch (25.4 mm) of thickness, plus 15 minutes for each additional inch (25.4 mm) of thickness.
Quenching: Oil or water to 150-125°F (66-51°C).
Tempering: Temper immediately after quenching. Hold at temperature for 1 hour per inch (25.4 mm) of thickness, 2 hours minimum, then air cool to ambient temperature. To minimize internal stresses in cross sections g
