High-strength high-plasticity stress-corrosion-resistant nano-structure aluminum alloy and preparation method thereof

Abstract

The invention relates to the field of nano-structure metal materials, in particular to a block nano-structure aluminum alloy with high strength, high plasticity and stress corrosion resistance and a preparation method. The nano-structure aluminum alloy comprises the following components in percentage by mass: 4.5-7% of Mg, and the balance of Al and a small amount of impurity elements. According to the block nano-structure aluminum alloy prepared through high-strain-rate high-speed deformation and high-temperature annealing, the microstructure of the block nano-structure aluminum alloy is composed of equiaxed superfine 200-1000 nm crystal grains, and the crystal boundary of the nanocrystalline is mainly composed of low-energy small-angle crystal boundaries. The block nanostructure aluminum alloy prepared through the method has high strength and plasticity matching, the room-temperature tensile strength reaches 350 MPa or above, the uniform ductility ranges from 15% to 20%, the percentage elongation after fracture ranges from 30% to 35%, the very excellent stress corrosion resistance is achieved, the slow strain rate tensile property of a sensitized sample in a 0.6 mol / L NaCl aqueous solution (pH = 3) is equivalent to that of air, and the plasticity loss rate is smaller than or equal to 10%. The method is suitable for preparation of high-strength and high-toughness structural members used in a harsh corrosion environment containing chloride ions.

Description

technical field [0001] The invention relates to the field of nanostructured metal materials, in particular to a bulk nanostructured aluminum alloy with high strength, high plasticity and stress corrosion resistance and a preparation method. Background technique [0002] Al-Mg-based alloys have high strength-to-weight ratio, formability, and good corrosion resistance, and are widely used as structural materials in transportation and marine environments. However, with the development of modern industry, higher requirements are put forward for the strength, plasticity and corrosion resistance of Al-Mg aluminum alloys. The mechanical strength required for the Al-Mg-based alloy can be achieved by solid solution strengthening. However, alloys supersaturated with Mg (i.e. >3 wt% Mg) are generally unstable at moderate or even low temperatures due to the presence of continuous chains of β(Al at the grain boundaries. 3 Mg 2 ) equilibrium phase precipitation. The intergranular β...

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Problems solved by technology

However, when the grain size of the material is refined to the submicron or even nanometer level, the movement of dislocations is greatly restricted, and the plasticity of the material is lost.

Although further high-temperature annealing can obtain better plasticity, the strength drops significantly, so that most of the strength raised by the grains disappears.

Therefore, grain refinement is often at the expense of the plasticity of the material. Using this method, it is often difficult to balance the strength and plasticity of aluminum alloys.

In addition, the high-density grain boundary introduced by plastic deformation has high energy, which tends to accelerate the chain distribution of precipitated phases at the grain boundary, resulting in the deterioration of the corrosion performance of the alloy.

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