COLOURING METHOD FOR WROUGHT ALUMINIUM ALLOY WELDED JOINT COLOUR METALLOGRAPHY

摘要

A colouring method for wrought aluminium alloy welded joint colour metallography, comprising pre-etching and colouring, wherein the pre-etching comprises an acid etching processing step. The acid etching processing is as follows: an acid etching solution is heated to 55ºC-65ºC, dripped onto a test piece surface for 50 s-60 s, then flushed with a large amount of deionized water and dried with hot air. The acid etching solution is an aqueous solution comprising 0.3-0.5 mol/L of Cl －, 1.4-1.8 mol/L of H ＋ and 0.3-0.5 mol/L of PO43-. The colouring is as follows: the test piece subjected to the pre-etching processing is completely immersed in a Weck reagent, shaken slightly for 5-10 s, flushed with a large amount of deionized water after surface colouring and dried with hot air. With the method, the success rate for test piece preparation is high, the repeatability is high, and the cost is low; the colour metallography of the wrought aluminium alloy welded joint processed using the method has the advantages of high contrast display, clear grain boundaries and high test result accuracy.