Ultrahigh-intensity, low-quenching sensitivity and weldable aluminum alloy, production technology and section bar processing method

Abstract

The invention discloses an ultrahigh-intensity, low-quenching sensitivity and weldable aluminum alloy, a production technology and a section bar processing method, wherein the aluminum alloy contains the following elements by weight: 0.15-0.22% of Ce, 0.9-1.4% of Mg, 2.5-3.0% of Zn, 0.35-0.8% of Cu, 0.8-1.2% of Si, 0.15-0.30% of Mn, 0.13-0.20% of Zr, 0.08-0.12% of Ti, and the balance being Al, wherein a sum of contents of Ti and Zr is not less than 0.25%, and a content of Fe is not more than 0.5%. Ce rare earth element introduced in order to optimize casting crystallization structure of the alloy, and generates a CeCu compound with Cu in order to supercool and refining an alloy crystallisation process and enhance crystal boundary, thereby preventing increase of welding crack sensitivity of aluminum because of Cu in a solid solution. Because of containing Si and Cu elements and optimization combination of a plurality of strengthening phase, the tensile strength of the alloy can reach more than 400MPa, and because of low Cu and Mn content and no Cr, the alloy quenching sensitivity is low, thereby making sure small dimension tolerance deformation of the section bar after extruding and quenching.

Description

technical field [0001] The invention relates to the technical field of aluminum alloy materials, in particular to a weldable aluminum alloy with ultra-high strength, low quenching sensitivity, a production process and a profile processing method. Background technique [0002] At present, aluminum alloy profiles used for structural components at home and abroad, such as trucks, trailers, cargo boxes, mine cars, skeletons, crossbars, corner columns, side columns and reinforcement bars, are required to have high strength and high fracture toughness, and can be welded . Most of them are 7 series, Al-Mg-Zn alloy and Al-Mg-Zn-Cu alloy, and 6066 alloy in 6 series are the main aluminum alloy materials. The former is represented by 7005 alloy, which has low quenching sensitivity and deformation resistance. Moderate, within the extrusion coefficient range, easy to extrude, high production efficiency, etc., but due to MgZn 2 and Al 2 Mg 3 Zn 3 As a limitation of the strengthening ...

AI Technical Summary

Problems solved by technology

[0004] However, there are only two types of weldable alloys with a tensile strength close to 400MPa that have been registered at home and abroad and are easy to extrude. One type: 6 series of Al-Mg-Si alloys, represented by 6066, whose composition is ( Weight percent) Si: 09-1.8; Mg: 08-1.4, Cu: 0.7-1.2; Mn: 0.6-1.1, its T6 state, the tensile strength at room temperature ≧ 395MPa, fracture toughness δ ≧ 12%, because it contains The amount of Cu is high, and the welding and corrosion resistance of the alloy are poor

In order to improve the performance, a large amount of Mn element is also added to the alloy as a grain refiner and structure improver, but the addition of Mn greatly improves the quenching sensitivity of the alloy, and the rapid quenching and cooling makes the alloy only extrude the cross section For simple and symmetrical profiles, when extruding asymmetric profiles, rapid quenching will cause rapid cooling and deformation of the profiles, and it is difficult to ensure that the dimensional tolerances are within the required range, resulting in low production efficiency, high production costs, and difficulty in popularization and use

[0005] The second category: Al-Mg-Zn alloy, representing 7005 alloy, its composition is (weight percent) Si: ≤0.35; Mg: 1-1.5; Zn: 4.0-5.0; Cr: 0.06-0.2; Ti: 0.01- 0.06; Zr: 0.08-0.20, this alloy is easy to extrude, and the quenching sensitivity is not high, but the tensile strength of the T6 state is ≧370MPa, and the fracture toughness δ≧10% cannot reach the strength above 400Mpa