Reasons for warping and loss of interference in liners made of the bimetal steel-antifriction aluminum alloy

Conclusions

• 1. The warping of liners (loss of interference) made by forging from the rolled bimetal steel — antifriction aluminum is due to residual compressive deformation of the aluminum alloy and nonuniform relaxation of the steel backing.

• 2. The comparatively slight warping due to residual deformation in the alloy can be reduced to a minimum by reducing the thickness of the alloy or increasing the thickness of the steel backing.

• 3. Liners must not be made of bimetal which has not been annealed after rolling. It is essential to improve the relaxation strength of the steel backing by annealing bimetal strip at 450–500°, which does not produce a layer of brittle chemical iron-aluminum compound on the interface.

  In recrystallazation annealing (550°) in order to prevent the alloy peeling off, it is essential to attach it to the steel through an underlayer of metal or alloy which does not form a weak chemical compound at this temperature on the interface with the steel.

• 4. To prevent the steel backing warping it is advisable to plate the liner surface with a thin layer (similar to the type used in lead bronze tractor liners) preventing local overheating of the liners, or else to use aluminum-base alloys with high antifriction properties [3].