Heat Treating of Aluminum Alloys. HEAT TREATING in its broadest sense, refers to any of the heating and cooling operations that are performed for the pur-. A:Let's first describe what is happening when you heat treat 2XXX, 6XXX, or 7XXX alloys. All of these alloys are heat treated by precipitation. The application of the term heat treatable to aluminium alloys, both wrought and cast, is restricted to the specific operations employed to increase strength and hardness by precipitation hardening thus the term heat treatable serves to distinguish the heat treatable alloys from those alloys in which no significant.


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How does the type of material, heat-treated or non-heat-treated, affect the completed strength of the heat treatment aluminium alloys In short, the difference in transverse tensile strength of the completed groove weld is governed by the reaction of the base material to the heating and cooling cycles during the welding operation.

Generally speaking, the non-heat-treatable alloys are annealed in the heat-affected zone adjacent to the weld. This is unavoidable when arc welding, as we will reach the annealing temperature, and extended time at these temperatures is not required in order to anneal the base material.

Aluminum Workshop: Achieving T6 designation for - The Fabricator

The heat-treatable alloys are usually not fully annealed during the welding operation but are subjected to a partial anneal and overaging process. These alloys are very susceptible to time at temperature; the higher the temperature and the longer at temperature, the more significant the loss of strength in the base material adjacent to the weld.

For this heat treatment aluminium alloys, it is important to control the overall heat input, preheating, and interpass temperatures when welding the heat-treatable alloys.

Typically, the common heat-treatable base alloys, such as T6, lose a substantial proportion of their mechanical strength after welding. Accompanying the structural reversion are changes in the various properties affected by cold working. These heat treatment aluminium alloys occur in several stages, according to temperature or time, and have led to the concept of different annealing mechanisms or processes.

The reduction in the number of dislocations is greatest at the center of the grain fragments, producing a subgrain structure with networks or groups of dislocations at the subgrain boundaries.

Heat treating of aluminum and aluminum alloys

With increasing time and heat treatment aluminium alloys of heating, polygonization becomes more nearly perfect and the subgrain size gradually increases. In this stage, many of the subgrains appear to have boundaries that are free of dislocation tangles and concentrations.

Recovery annealing is also accompanied by changes in other properties of cold worked aluminum. Complete recovery from the effects of cold working is obtained only with recrystallization.


Recrystallization is characterized by the gradual formation and appearance of a microscopically resolvable grain structure. The new structure is largely strain-free-there are few if any dislocations within the grains and no concentrations at the grain boundaries. Grain Growth After Recrystallization.

Heating after recrystallization may produce heat treatment aluminium alloys coarsening.

  • The Differences Between Heat-Treatable and Non-Heat-Treatable Aluminum Alloys

This can take one of several forms. The heat treatable alloys contain amounts of soluble alloying elements that exceed the equilibrium solid solubility limit at room and moderately higher temperatures.

Heat treating of aluminum and aluminum alloys

The amount present may be less or more than the maximum that is soluble at the eutectic temperature. Nature of Precipitates and Sources of Hardening.

Intensive research during the past forty years has resulted in a progressive accumulation of knowledge concerning the atomic and crystallographic structural changes that occur in supersaturated solid solutions during precipitation and the mechanisms through which the structures form and alter alloy properties.

In most precipitation-hardenable systems, a complex heat treatment aluminium alloys of time-dependent and temperature-dependent changes is involved. Kinetics heat treatment aluminium alloys Solution and Precipitation.

The relative rates at which solution and precipitation reactions occur with different solutes depend upon the respective diffusion rates, in addition to solubilities and alloy contents.

The Differences Between Heat-Treatable and Non-Heat-Treatable Aluminum Alloys

Can you tell me the heat treatment steps necessary to produce T6? I have heard that heat treating it after welding will increase its mechanical properties. Heat treatment aluminium alloys of these alloys are heat treated by precipitation hardening.

This involves two steps—solution heat treating and aging.