PACIFIC S7 has exceptional impact properties plus the highest hardenability of the 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.
Heat Analysis - ranges and limits %
Heat to 1950/2050°F, do not forge below 1700°F.
Heat to 1500/1550°F and hold 1 to 4 hours depending on part size. Cool at a maximum rate of 25°F per hour to 950°F (cooling rate below 950°F is not critical). Typical annealed hardness is 187/223 HB.
Heat to 1200/1250°F for 1 hour minimum at temperature and cool in air.
Preheat at 1200/1300°F. Austenitize at 1700/1750°F for 15 to 45 minutes and cool in air to harden (larger sections may have to be oil quenched for maximum hardness). Typical as quenched hardness is 60/61 HRC.
Temper at 400/1150°F to an expected hardness of 45/57 HRC; 400/500°F is typical for cold working applications and 900/1000°F for hot working.
Resistance to fracture by impact at high hardness is often the reason for using S7. Results from Bethlehem, Crucible and Latrobe steel companies using unnotched, C-notched and V-notched Charpy impact tests show the same. There is a toughness peak reached by tempering in the range of 450/600°F with resulting hardnesses 55/57 HRC. Even higher toughness can be achieved by tempering above 1000°F. However, hardness will drop to approximately 50 HRC and lower as tempering temperature increases.
Tempering Temperature °F
Approximate Hardness, HRC
Shapes and Conditions Available
Annealed Rounds through 8" Diameter
SE® Flats & Squares from 1/2" through 3" Thickness