Abstract
This paper presents non-destructive testing (NDT) results for the detection of bond defects in aluminium-tin (Al-Sn) alloy/steel bimetal strips. Among all types of bimetal strip that are used in the automotive industry for plain journal engine bearings, Al-Sn alloys cold roll bonded (CRB) onto steel backing is the most common type. The difficulty to evaluate the metallurgical bond between the two dissimilar metals is a major industrial concern, which comprises the risk that bearings fail in the field. Considering the harsh performance requirements, 100% online non-destructive testing would be desirable to significantly reduce the business risk. Nowadays bimetal strip manufacturers still rely on destructive testing through different peel-off tests. This work offers the results from four independent NDT studies, using active thermography, shearography, ultrasound and guided wave electromagnetic acoustic transducers (EMATs) and samples with different artificially implanted defects, to explore the feasibility to qualitatively indicate the occurrence of bond defects. A destructive peel off test was used to correlate the NDT results with known bond quality. The studies were done under laboratory conditions, and in case of ultrasound also online under production conditions. During the ultrasound online test, the requirements that a NDT technique has to fulfil for online inspection of Al-Sn alloy/steel bimetal strip were established. For active thermography, shearography and guided wave EMAT techniques, it was theoretically analysed, if the laboratory test results could be transferred to testing under production conditions. As a result, guided waves using EMATs, among the four tested methods, are best suited for online inspection of Al-Sn alloy/steel bimetal strip. This research was carried out in collaboration with MAHLE Engine Systems UK Ltd., an Al-Sn alloy/steel bimetal strip manufacturer for the automotive industry.
Highlights
Al-Sn alloy/steel bimetal strips are used for engine bearings in the automotive industry due to the ideal hybrid properties of Al-Sn alloy and steel [1]
A case study of thermography, shearography, ultrasound and guided wave electromagnetic acoustic transducers (EMATs) testing of the bond integrity of Al-Sn alloy/steel bimetal strips is given in this paper
It was demonstrated that each non-destructive testing (NDT) technique is capable to detect delamination between clad Al and steel layers under laboratory conditions, but has specific advantages and limitations
Summary
Al-Sn alloy/steel bimetal strips are used for engine bearings in the automotive industry due to the ideal hybrid properties of Al-Sn alloy and steel [1]. The aluminium alloy that is in sliding contact between the surfaces has embedability, conformability and compatibility properties, which are achieved by adding tin as an alloying element [3]. This is required to resist welding between the sliding surfaces, allow clearance under the heat, pressure and foreign particles that are present in an engine. Clad aluminium-steel products are either manufactured by roll bonding, explosion welding or fusing [4]. This work is based on bimetal strips for which the clad Al is cold roll bonded (CRB) to steel. In CRB the solid state weld is achieved by a substantial and simultaneous plastic deformation of the
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
