Functional Layers of Aluminium Alloy on Steel Made by Alternative Friction Processes, for Elements of Metal Structures

摘要

Coating of steel with aluminium alloy is needed for the execution of a functional layerfor corrosion protection. Some experiments have been performed on square-section tubes (50 mm x50 mm) of S235 steel, according to EN 10 025, to be coated with 1 mm thick sheets of EN AW5754 aluminium alloy that have been previously bended as U shaped profiles.A new experimental model of specialized equipment has been used for certain experiments to makethese functional layers of aluminium alloy on steel.Firstly, friction drilling and threading by form tapping, followed by screws-mounting without nutshave been used to make such joints.Several holes have been executed by a 04.3 friction drilling tool, then an M5 form tap was used forthreading. For friction drilling, tools with 90% tungsten carbide content and 1 micron grain sizewere applied. By threading, TiN coated form taps have been used.Secondly, overlap friction stir welding (FSW) has been applied, to make a functional layer ofaluminium alloy on a 50 mm x 50 mm S235 steel tube. The wings of the U profiles wereoverlapped. A quenched FSW tool, own-made of C 45 grade steel, EN 10083, has been used forthese joining tests.