L6 - Low Alloy Special Purpose Tool Steels

Topics Covered

Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Other Designations
Fabrication and Heat Treatment
     Tempering
     Annealing
     Cold Working
     Welding
     Forging
     Forming
     Machinability
     Heat Treatment
Applications

Introduction

Low alloy special purpose steels or group L steels contain small quantities of chromium, nickel, vanadium, and molybdenum. L2 and L6 form the group L steels.

The L6 tool steels contain 0.70% carbon with a quenched hardness of about 64 HRC. The alloying elements in these tools steels are chromium and molybdenum, and 1.50% nickel to increase toughness. These tool steels can maintain hardness above 60 HRC for sections of 75 mm (3 in.) thickness.

The sections below provide an overview of L6 tool steels.

Chemical Composition

The chemical composition of L6 tool steels is outlined in the following table.

Element Content (%)
Carbon, C 0.65-0.75
Manganese, Mn 0.25-0.80
Silicon, Si 0.50
Cromium, Cr 0.60-1.20
Nickel, Ni 1.25-2.00
Molybdenum, Mo 0.50
Vanadium, V 0.20-0.30(a)
Copper, Cu 0.25
Phosphorus, P 0.03
Sulpher, S 0.03
Iron, Fe Balance

Physical Properties

The following table shows the physical properties of L6 tool steels.

Properties Metric Imperial
Melting point 2590°F 1421°C
Density 7.86 g/cc 0.284 lb/in3

Mechanical Properties

The mechanical properties of L6 tool steels are displayed in the following table.

Properties Metric Imperial
Poisson's ratio 0.27-0.30 0.27-0.30
Elastic modulus 190-210 GPa 27557-30457 ksi

Other Designations

Analyze Your Metals | Request a Quote

Equivalent materials to L6 tool steels are:

  • UNS T61206
  • ASTM A681
  • DIN 1.2713
  • SAE J437
  • SAE J438

Fabrication and Heat Treatment

Tempering

L6 tool steels are tempered between 177 to 538°C (350 to 1000°F) for Rockwell C 62 to 45 range.

Annealing

L6 tool steels are annealed at 788°C (1450°F) and cooled slowly at a maximum of 4°C (40°F) per hour.

Cold Working

Conventional methods are used for cold working of L6 tool steels.

Welding

L6 tool steels are generally weldable in nature.

Forging

L6 tool steels are forged at 1079°C (1975°F) down to 871°C (1600°F). These steels should not be forged below 843°C (1550°F).

Forming

Conventional methods are used for forming of L6 tool steels.

Machinability

L6 tool steels have extremely good machinability that is rated at 90% in comparison with the machinability of W group water hardening low alloy steels that are rated 100% as a baseline.

Heat Treatment

L6 tool steels are heated slowly to 816°C (1500°F) and then held for 10 to 30 minutes. This is followed by water or oil quenching.

Applications

L6 tool steels are used in springs, bearings, chuck parts or rollers.

Tell Us What You Think

Do you have a review, update or anything you would like to add to this article?

Leave your feedback
Submit