S7 Shock Resisting Tool Steel

S7 toolsteel has exceptional impact properties plus the highest hardenability of shock resisting grades of tool steel.It also possesses good softening resistance at high temperatures which gives it hot work capabilities.Because of its unusual combination of properties, S7 is suitable for a wide range of tool and die applications.It is used for hot and cold shock applications, medium hot-work dies and medium-run cold work tools and dies.
Typical Applications
Shear Blades Extrusion Dies Leaf Springs
Bending Dies Gripper Dies Pipe Cutters
Chisels Hot Header Dies Plastic Molds
Die Casting Dies Mandrals Punches
Zinc Die Casting Dies Collets Cold Forming Dies
Colour Code Stocked Sizes
Yellow & Black
(Bar end) 



Rounds 25 mm - 102 mm Dia
250 mm
Related Specifications
Germany W-nr 1.2357
Chemical Composition
Carbon 0.50
Silicon 0.30
Manganese 0.60
Chromium 3.30
Molybdenum 1.40
Vanadium 0.20
Physical Properties
Elastic Modulus
Density 7.83 g/cm³
Thermal Conductivity W/m- °K Cal/cm-s-°C
at 95°C 28.5 0.068
Thermal Properties
Critical Temperature: 800c
CTE, linear 20°C 12.59µm/m- °C
CTE, linear 250°C 13.33µm/m- °C
CTE,linear 500°C 14.27µm/m- °C
Transformation Temperature 785 °C
*Material stocked in annealed condition
Heat Treatment
Heat to 845C,hold for 2hours, slow cool 30C per hour to 540C then air cool.
Or heat to 845C, hold 2hrs., cool to 760C hold 4hrs,then air cool
Annealed Hardness About BHN 187/220
Stress Relief
Annealed Parts: Heat to 650-675°C, hold for 2hours, then cool in still air.
Hardened Parts: Heat to 15-30°C below the original tempering temperature, hold for 2 hours, then cool in still air
Preheat: Heat to 730-760C, equalize
Austenitize: 940-955C, Hold time at temperature 30-45 minutes
Quench: Air, positive pressure quench 2bar minimum or interrupted oil to below 65C
Sections above >75mm may require interrupted oil quench or higher bar pressure.
Oil quench to 540-595C, then air cool to handwarm
Temper: 205-540°C
Temper 2hours minimum or at least 1hour per 25mm of thickness. Double Tempering is recommended.
Cool to room temperature in between tempers.
Size Change: 0.10% when air cooled from 940/955°C and tempered at 205°C
Heat Treat Response
Hardness and Impact Toughness Data
Austenitized 940°C Air Cool
HRC Charpy C-Notch
As Air Quenched 59-61 62
205°C 55-58 171
260° 54-56 169
315° 53-55 156
370° 52-54 142
420° 52-54 138
480° 51-53 163
540° 50-52 203
595° 46-48 257
650° 40-42 ___
705° 33-35 ___
* Note all values are approximate and depend on type of heat treatment and quenching rates.
Flame, Induction Hardening or Nitriding Steel
Very good Flame, Induction Hardening and Nitriding Steel
Welding should be carried out by an experienced Die repair welder.
Choice of weld consumable, consult your supplier. Preheating and retempering of work piece is a must.
S7 has good polishability in the hardened and tempered condition.Normal polishing techniques
should be followed, taking care not to over polish as this will lead to a poor surface finish.
Hard Chrome Plating
After hard chrome plating, tool should be tempered for approximately 4 hours at 180°C so
as to avoid hydrogen embrittlement.
Interlloy believes the information provided is accurate and reliable. However no warranty of accuracy, completeness or reliability is given, nor will any responsibility be taken for errors or omissions.