Kabushiki Kaisha Kobe Seiko Sho

Takehiko Eto

Manabu Nakai

Mitsuo Hino

Yoshimitsu Miyagi

Masahiro Shimamura

Tetsunari Iida

Kiko Hirose

Yagoro Hirose

A heat treatable 7000 series aluminum alloy has a micro-structure with a crystal grain size of 45 .mu.m or less and an aspect ratio (longitudinal/long transverse ratio of crystal grain) of preferably 4 or less, whereby its corrosion resistance is improved outstandingly by applying a solution heat treatment and hardening and subsequently, applying an aging treatment at 100 to 145.degree. C. for 5 to 50 hr, a reversion treatment at 140 to 195.degree. C. for 0.5 to 30 hr. and a re-aging treatment at 100 to 145.degree. C. for 5 to 50 hr. to thereby make an electroconductivity to 38-40 IACS %, and render the micro-structure so as to have a minimum distance for the .eta. phase on the crystal grain boundary of 20 nm or more and a maximum size for the .eta.' phase in the crystal grain of 20 nm or less.

High strength heat treatable 7000 series aluminum alloy of excellent

There is provided Al alloys which have improved and excellent fracture toughness and fatigue characteristic and improved formability, and which can be suitably used for transportation machines, such as aircraft, railway vehicles, general mechanical parts and the like. The Al alloy contains 1 to 8% (% by weight, the same is true for the following) of Cu, containing one or more selected from a group comprising 0.4 to 0.8% of Mn, 0.15 to 0.3% of Cr, 0.05 to 0.1% of Zr and 0.1 to 2.5% of Mg, Fe and Si each being less than 0.1%, a distance between constituents being more than 85 .mu.m, and having a micro-structure fulfilling at least one of the following (a) to (c):

Heat treatable Al alloys excellent in fracture touchness, fatigue

An aluminium alloy with superior thermal neutron absorptivity contains 0.2-30 wt. % of Gd. An aluminium alloy for an wrought material with high-temperature strength contains 0.2-20 wt. % of Gd and 0.5-6 wt. % of Mg. An aluminium alloy for casting contains 0.2-10 wt. % of Gd and 6-12 wt. % of Si.

Aluminum alloy with superior thermal neutron absorptivity

Sheets of high strength superplastic Al--Zn--Mg alloys or Al--Cu alloys which having a maximum grain size below 30 .mu.m on average are described. These alloy sheets are obtained by a method which is characterized by keeping a homogenized and hot worked ingot of the alloy at two different temperatures for sufficient times whereby a fine grain structure is formed in the alloy to impart superplasticity to the alloy.

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Kobe, Japan

Takehiko Eto