T4 and T6 heat treatments are mostly used for the manufacturing of parts for the aerospace and automotive industries. Pyradia, positioned as a major manufacturer of industrial furnaces, is a major player in a geographical area (province of Quebec) recognized for its know-how in the production of raw aluminum from foundries and structural aluminum parts manufactured in specialized factories and workshops.

But what is T4 and T6 heat treatment? To better understand, we must first provide an overview of the intrinsic characteristics of aluminum.

Introduction:

Aluminum is an abundant element in nature. It is a lightweight, relatively rigid and corrosion-resistant material (in neutral PH conditions). This makes it a material of choice that enable its transformation with a variety of finishing processes to make them aesthetic metal parts for many applications.

It is however necessary to increase its mechanical strength before it undergoes permanent deformation. It is obvious that a critical piece of equipment can’t deform during its duty and while in service.

The physical characteristics of aluminum alloys:

The main characteristics of the aluminium and its alloys to be aware of are:

• The melting point of pure aluminum is about 650°C (1200°F).
• The melting point of different aluminum alloys is between 463-671°C (865-1240°F).
• Its oxidation is very slow – there is no need for heat treatment in an inert atmosphere.
• High sensitivity to radiation heating – Indirect air convection heating is the best mean to treat aluminum alloys.
• Stable crystal lattice (face-centered cubic) – From solidification to room temperature.

T4 and T6 heat treatments:

T4 and T6 heat treatment consist essentially of a three-step process:

1. Solution: Dissolution of soluble phases in the solid state. Heating temperatures of 480-550°C (896-1022°F) for several hours (up to 12 hours)

Temperature/time diagram for aluminum solution

2. Quenching: Rapid cooling (with water or glycol) to create a state of supersaturation.

3.  Aging: Tempered at room temperature (T4) or high temperature (typically between 160-190°C (320-375°F)) for a period of 3-5 hours (T6) for hardening the alloy by intermediate-phase precipitation

Natural Aging T4

T6 High Temperature Aging

These heat treatments enable improving the mechanical strength of aerospace parts and the durability of the automotive parts. Improved shaping and corrosion resistance are very useful properties for structural and architectural parts.     

Pyradia furnaces for heat treatment of aluminium type T4 and T6

Indirect gas fired model GDQ (Working basket dimensions: 108in (9ft) W x 132in (11ft) D x 96in (8ft) H

Electric powered model no. EDQ 060072060 (Working basket dimensions: 48in (4ft) W x 60in (6ft) D x 48in (4ft)

Electric powered model no. EDQ 078078148 (Working basket dimensions: 60in (5ft) W x 60in (5ft) D x 120in (10ft)

Electric powered model no. EDQ 060084060 (Working basket dimensions: 48in (4ft) W x 72in (6ft) D x 48in (4ft)

Typical load in drop bottom work basket 48in (4ft) W x 72in (6f) D x 48in (4ft) H

Casted parts on Heat Treating jig

Cladding parts set in Working basket 108in (9ft) W x 132in (11ft) D x 96in (8ft) H