AISI S7 Shock Resistant Tool Steel

• (Machine finish) T & B WITH SAW-CUT EDGES
• (Machine finish) FOUR SIDES

DESCRIPTION

Shock steel with exceptional impact properties. Since it hardens in air, it is safe and stable in heat treatment. Most remarkable characteristic is its versatility. Used widely for medium-run cold-work tools and dies, for plastic-molding dies, for shear blades, for medium hot-work dies, for master hobs, and for component parts of many products.

ADVANTAGES

• Good machinability
• Maximum shock resistance
• Air hardening
• Cold & medium hot-work characteristics

TYPICAL ANALYSIS

CARBON ………………..0.50 SILICON …………………0.25

MANGANESE ………….0.70 CHROMIUM ……………3.25

MOLYBDENUM ……….1.40

HEAT TREATMENT

FORGING ………………………………..Preheat 1200°F to 1300°F; forge at 2000°F to 2050°F, stop at

1700°F and cool slowly

NORMALIZING ………………………...Do not normalize

ANNEALING ……………………………1500°F to 1550°F, cool slowly to 1000°F, air-cool, Brinell 197 max

PREHEATING ……………………………1200°F to 1300°F, prior to hardening

HARDENING …………………………….1725 °F. Quench in air if cross-section is 2-1/2 in. or smaller;

sections 2-1/2 in. to 6 in. should be oil-quenched to black

(1000°F) followed by air-cooling to 150°F; larger cross-sections

should be oil-quenched to 150°F.

TEMPERING ……………………………...400° F minimum. Double tempered is recommended.

MACHINABILITY

Rated at 95 annealed to Brinell 197 max., as compared to a rating of 100 for a one percent carbon tool steel.

DIMENSIONAL STABILITY

Can be expected to expand no more than 0.001 in./in. of cross-section when quenched in air from the proper hardening temperature.

IMPACT PROPERTIES

To determine impact properties, unnotched Charpy impact specimens were selected. They were machined over-size, heat-treated, and finish-ground to 0.250 in x 0.375 in x 2.165in. The heat treatment consisted of preheating at 1300F, and tempering at increasing temperatures.

*Maximum impact value obtained on impact testing machine.