Process to improve 6XXX alloys by reducing altered density sites

US6613167B2 · kind B2 · utility

Assignee

• ALCOA INC. · US

Inventors

• Paul E. Magnusen · Pittsburgh, US
• Dhruba J. Chakrabarti · Export, US
• Anne E. Zemo · Riverdale, US
• Robert W. Westerlund · Bettendorf, US
• Anthony Morales · Bettendorf, US
• Daniel T. Moulton · Bettendorf, US

Key dates

• Filing date: Jun 1, 2001
• Grant date: Sep 2, 2003
• Expiry date: Jun 22, 2021

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/12764
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A process for improving 6XXX alloys, such as 6013, preferably includes heating, hot rolling, inter-rolling thermal treatment at a very high temperature such as 1020° F. or more, again hot rolling (with or without subsequent continuous hot rolling or cold rolling or both), solution heat treating and artificial aging. The initial heating, inter-rolling, thermal treatment and solution treatment, especially the latter two, are carried out at very high temperatures such as 1030° F. Each aforesaid hot rolling stage produces substantial metal thickness reduction. The improved sheet or plate product has a substantially reduced occurrence of reduced density features revealed in scanning electron microscope examination at 500× and exhibits improved (reduced) fatigue crack growth rate providing an advantage in aerospace applications such as fuselage skin, especially fuselage belly skin.