MX2017005153A - Ultra high strength 6xxx forged aluminium alloys. - Google Patents

Abstract

An aluminium alloy forged product obtained by following steps: a) casting a billet from a 6xxx aluminium alloy comprising: Si: 0.7-1.3 wt. %; Fe : = 0.5 wt. %; Cu: 0.1-1.5 wt. %; Mn: 0.4-1.0 wt. %; Mg: 0.6-1.2 wt. %; Cr: 0.05-0.25 wt.%; Zr: 0.05-0.2 wt. %; Zn: = 0.2 wt.%; Ti: = 0.2 wt.%, the rest being aluminium and inevitable impurities; b) homogenising the cast billet at a temperature TH, which is 5°C to 80°C lower than solidus temperature Ts, in the range of typically 500-560°C, for a duration between 2 and 10 hours; c) quenching said billet down to room temperature by using water quench system; d) heating the homogenised billet to a temperature between (Ts - 5°C) and (Ts - 125°C); e) extruding said billet through a die to produce a solid section with an exit temperature (typically 530°C) lower than Ts (typically 550°C), and with an extruding ratio of at least 8; f) quenching the extruded product down to room temperature by using water quench system; g) stretching the extruded product to obtain a plastic deformation typically between 0.5% and 10%; h) heating cut-to-length extruded rod to forging temperature, typically between 400 and 520°C; i) forging in heated mould between 150 and 350°C; )) separate solutionising at a temperature between 530 and 560°C for durations between 2 min. and 1 hour; k) water quenching the forged and solutionised material down to room temperature; 1) room temperature ageing for a duration between 6 hours and 30 days; m) ageing to T6 temper by a one-or multiple-step heat treatment at temperatures ranging from 150 to 200°C for holding times ranging from 2 to 20 hours, and its ultimate tensile strength is higher than 400 MPa.