Process to improve 6XXX alloys by reducing altered density sites

US6911099B2 · 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: Oct 29, 2002
• Grant date: Jun 28, 2005
• Expiry date: Feb 23, 2023

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 500X and exhibits improved (reduced) fatigue crack growth rate providing an advantage in aerospace applications such as fuselage skin, especially fuselage belly skin.