In early practice of autofrettage of a gun barrel, the barrel was pressurized hydraulically. In modern practice, a slightly oversized die is pushed slowly through the barrel by a hydraulically driven ram. The amount of initial underbore and oversize of the die are calculated to strain the material around the bore past its elastic limit into plastic deformation. A residual compressive stress remains on the barrel's inner surface, even after final honing and rifling.
The technique has been applied to the expansion of tubular components down hole in oil and gas wells. The method has been patented by the Norwegian oil service company, Meta, which uses it to connect concentric tubular components with sealing and strength properties outlined above.
The term autofrettage is also used to describe a step in manufacturing of composite overwrapped pressure vessel (COPV) where the liner is expanded (by plastic deformation), inside the composite overwrap.[2]
In early practice of autofrettage of a gun barrel, the barrel was pressurized hydraulically. In modern practice, a slightly oversized die is pushed slowly through the barrel by a hydraulically driven ram. The amount of initial underbore and oversize of the die are calculated to strain the material around the bore past its elastic limit into plastic deformation. A residual compressive stress remains on the barrel's inner surface, even after final honing and rifling.The technique has been applied to the expansion of tubular components down hole in oil and gas wells. The method has been patented by the Norwegian oil service company, Meta, which uses it to connect concentric tubular components with sealing and strength properties outlined above.The term autofrettage is also used to describe a step in manufacturing of composite overwrapped pressure vessel (COPV) where the liner is expanded (by plastic deformation), inside the composite overwrap.[2]
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