Grade M48 Tool Steel (UNS T11348)

Topics Covered

Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Fabrication and Heat treatment
     Machinability
     Forming
     Heat Treatment
     Forging
     Cold Working
     Annealing
     Tempering
Applications

Introduction

Tools steels are mainly used for manufacturing tools used in machining plastics, metals and woods. However, tool steels must be fabricated into the desired shape before they are able to be used. They have good toughness, wear resistance, machinability and resistance to decarburization.

AISI T4 tool steel is a high speed, tungsten type tool steel. It is a deep hardening alloy capable of Rockwell C 64 hardness.

The following datasheet will provide an overview of grade T4 tool steels.

Chemical Composition

The chemical composition of T4 tool steels is outlined in the following table.

Element Content (%)
Tungsten, W 17.5 - 19
Cobalt, Co 4.25 - 5.75
Chromium, Cr 3.75 - 4.5
Vanadium, V 0.8 - 1.2
Carbon, C 0.7 - 0.8
Molybdenum, Mo 0.4 - 1
Silicon, Si 0.2 - 0.4
Manganese, Mn 0.1 - 0.4
Phosphorus, P 0.03 max
Sulfur, S 0.03 max
Iron, Fe Balance

Physical Properties

The following table shows the physical properties of T4 tool steels.

Properties Metric Imperial
Density 8.68 g/cm3 0.313 lb/in3
Melting point 1432°C 2610°F

Mechanical Properties

The mechanical properties of T4 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

Thermal Properties

The thermal properties of T4 tool steels are given in the following table

Properties Metric Imperial
Thermal expansion co-efficient 11.9 µm/m°C 6.6 µin/in°F

Fabrication and Heat treatment

Machinability

The machinability of T4 tool steel is 55%.

Forming

T4 tool steel has good ductility in annealed condition and can be formed by conventional methods.

Heat Treatment

T4 tool steel is pre-heated to 843°C (1550°F) and rapidly heated to 1274°C (2325°F). It is then quenched in oil, air or salt bath.

Forging

Forging of T4 tool steel can be carried out from 968 to 1149°C (1775 to 2100°F).

Cold Working

T4 tool steel can be cold worked in the annealed condition using conventional method.

Annealing

Annealing of T4 steel is performed at 885°C (1625°F) followed by slow cooling.

Tempering

T4 tool steel is tempered at 538 to 593°C (1000 to 1100°F) to obtain Rockwell C hardness of 66 to 62.

Applications

The following are the list of applications of T4 tool steels:

  • Cutting tools
  • Cold extrusion punches
  • Broaches

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