Grade D7 Tool Steel (UNS T30407)

Topics Covered

Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Fabrication and Heat treatment
     Forging
     Annealing
Stress Relieving
     Hardening
Tempering
Applications

Introduction

The AISI grades of tool steels are the most common scale used to identify various grades of tool steel. The higher carbon grade tool steels are typically used for applications such as stamping dies, metal cutting tools, etc.

AISI D7 tool steel is a high-carbon, high-chromium air-hardening tool steel that exhibits exceptional wear resistance, with added carbon and vanadium.

The data below will provide an overview of grade D7 tool steels.

Chemical Composition

The chemical composition of D7 tool steels is outlined in the following table.

Element Content (%)
Iron, Fe 79.3
Chromium, Cr 12.5
Vanadium, V 4
Carbon, C 2.3
Molybdenum, Mo 1.1
Silicon, Si 0.4
Manganese, Mn 0.4

Physical Properties

The following table shows the physical properties of D7 tool steels.

Properties Metric Imperial
Density 7.7-8.03 g/cm3 0.278 – 0.290 lb/in3

Mechanical Properties

The mechanical properties of D7 tool steels are displayed in the following table.

Properties Metric Imperial
Modulus of elasticity 190-210 GPa 27557-30458 ksi
Poisson’s ratio 0.27-0.30 0.27-0.30
Hardness, Rockwell C 62.5 62.5
Izod impact unnotched 21.7 J 16 ft.lb

Fabrication and Heat treatment

Forging

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D7 tool steel is slowly heated at 1093 - 1149°C (2050 - 2100°F). The forgings are then cooled slowly in dry sand or in other insulating media.

Annealing

D7 tool steel is heated at 871 - 899°C (1600 -1650°F) for 2 hours and cooled to 538°C (1000°F).

Stress Relieving

To relieve machining stresses, A11 tool steels are heated to a temperature of 621 - 677°C (1150 - 1300°F) and then slowly cooled in still air.

Hardening

D7 tool steel is hardened at (1900-2000°F) and slowly cooled in air.

Tempering

Tempering of D7 tool steel is carried out at (400-1000°F) for 1 h.

Applications

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

  • Brick mold liners
  • Powder compaction tooling
  • Shot blasting equipment liners
  • Flattening rolls
  • Powder compaction tooling
  • Tools for ceramic extrusion and molding.

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