AISI D7 Tool Steel

D7 tool steel is a high-carbon, high-chromium air-hardening tool steel that exhibits exceptional wear resistance. The high carbon and vanadium contents result in numerous, hard vanadium carbide particles in the steel. These carbides exhibit a hardness that is equivalent to approximately 80 to 85 Rockwell C.

The following are the list of applications of D7 tool steels:

l Brick mold liners

l Powder compaction tooling

l Shot blasting equipment liners

l Flattening rolls

l Powder compaction tooling

l Tools for ceramic extrusion and molding.

Designations:

ASTM A681-US
FED QQ-T-570-US
SAE J437-US
SAE J438-US
UNS T30407-US
AISI D7 Tool Steel-US

Chemical composition(mass fraction)(wt.%) of the D7

MECHANICAL PROPERTIES

Forging/Rolling:

Preheat to 1500° F and soak thoroughly.  Then raise to 2050° F - 2125° F.  Do not forge or roll below 1800° F, cool slowly from the forging or rolling temperature.  Do not normalize.

Annealing:

Heat slowly to 1600° F - 1650° F, and hold for uniformity, furnace cool at a rate of 20° F per hour to 1000° F then air cool.  Expect Brinell hardness 235 - 262.

Hardening:

Preheat to 1500° F and soak until uniformly heated and either transfer or raise furnace temperature to 1850° F - 1950° F, and hold 1 hour per inch of greatest thickness.  Cool in still air.

Tempering:

Temper immediately after quenching, before part has cooled to below 150° F.  Parts should be held a minimum of 2 hours per inch of greatest thickness.  Double tempering is recommended.   For maximum wear resistance temper at 300° F.  The above tempering table may be used as a guide.  However, since 1/2" dia. specimens were used for this test, it may be found that heavier sections are several points lower.