A CASE STUDY ON FAILURE ANALYSIS OF AA 6063 BILLETS DURING EXTRUSION PROCESS

摘要

Hindalco produces Wagstaff billets of aluminium alloys for downstream processing by different customers. A typical case of frequent failure of AA6063 billets at the customer's end during extrusion process was observed. Failure was due to sagging and breaking of billet after preheating and during extrusion process. To find out the reasons of failure, a systematic comparative study was conducted using as supplied and failed samples. PoDFA analysis and chemistry of the supplied material showed no significant reason for failure. On the other hand, macro and microstructural analysis of the samples revealed interesting observations like rosette formation, grain boundary melting, eutectic and script like structures in the preheated billet samples. These observations indicate that the failure is the result of overheating and liquidation of the metal during preheating process.