APPROACHING BOLT LOAD RETENTION BEHAVIOUR OF AS41 THROUGH COMPLIANCE AND CREEP DEFORMATION

Bolt load retention (BLR) test is a practical way to quantify the degree of fastener clamp load retained at bolted joint in an engineering assembly. This is especially important for automotive power train applications working at elevated temperatures above 100 degrees C. BLR behaviour, creep and microstructure are important to achieve more heat resistant Mg-alloys for automotive power train application. In this study, these methods of investigation were used to analyse the elevated temperature properties of permanent mould cast AS41. Investigations were carried out at temperatures between 100 degrees C and 175 degrees C and stresses of 40-90 MPa. Stress exponent values of similar to 2 at low stress regions of 40 and 55 MPa, and between 4-6 at high stress regions of 70 and 90 MPa suggest grain boundary sliding and dislocation climb as deformation mechanism during creep. The prediction of the BLR behaviour and experimental results are in good agreement.