FSW as a repair technique for surface cracks in stainless steel

TWI Industrial Member Report Summary 880/2007

By W J Kyffin

Background

Advances in friction stir welding (FSW) tool materials have led to a growing interest in using FSW to join high temperature materials, such as steel. One important application of this technology is the repair of cracked and/or damaged stainless steel components. The long term and extensive use of austenitic stainless steel, covering a wide range of industry sectors, means that performing an in-situ repair is often more economically desirable than replacing the component. This report presents the results of an initial feasibility study investigating FSW as a technique for repairing stainless steel components.

Objectives

The objectives of this work were to:

• Determine effective welding parameters for the production of good quality friction stir welds in 304L stainless steel.
• Demonstrate that surface breaking defects in 304L stainless steel can be sealed by FSW.
• Determine the downforce required, for a number of tool geometries, to generate good quality friction stir welds when processed in force-control.