阅读说明：本技术 一种铝锂合金厚板均质细晶的加工成型方法 (Processing and forming method of aluminum-lithium alloy thick plate homogeneous fine grains ) 是由 王海军 张帅 万东海 杨贵生 李向东 代坤义 赵晓光 张明桥 于 2020-04-29 设计创作，主要内容包括：一种铝锂合金厚板均质细晶的加工成型方法,步骤(1)合金铸锭退火(2)定向快锻开坯(3)热轧制成型。本发明通过短时间内的大变形量,完全破碎铸态组织中大量树枝晶和等轴粗晶,获得细小且均匀的晶粒组织并减少气孔、疏松等冶金缺陷；然后采用低温轧制和高温轧制结合的工艺方法进而制备出各方向的组织和晶粒细小均匀的厚板,通过细晶强化方法同时提高材料强度和塑韧性,明显减少铝锂合金各向异性问题,制备出各方向的组织和晶粒细小均匀的厚板,提高材料强韧性,并减小铝锂合金各向异性问题并有效减小铝锂合金各向异性问题,满足制造航天航空用60mm以上大厚规格铝锂合金制件的要求。(A processing and forming method of aluminum-lithium alloy thick plate homogeneous fine grains comprises the steps of (1) alloy ingot casting annealing, (2) directional fast forging and cogging, and (3) hot rolling and forming. According to the invention, a large amount of dendrites and equiaxed coarse crystals in the as-cast structure are completely crushed by a large deformation in a short time, so that a fine and uniform grain structure is obtained, and metallurgical defects such as pores and porosity are reduced; and then, a process method combining low-temperature rolling and high-temperature rolling is adopted to prepare thick plates with fine and uniform tissues and grains in all directions, the strength and the plastic toughness of the material are improved by a fine grain strengthening method, the problem of the anisotropy of the aluminum lithium alloy is obviously reduced, the thick plates with fine and uniform tissues and grains in all directions are prepared, the toughness of the material is improved, the problem of the anisotropy of the aluminum lithium alloy is reduced, the problem of the anisotropy of the aluminum lithium alloy is effectively reduced, and the requirement for manufacturing large-thickness aluminum lithium alloy parts with the thickness of more than 60mm for aerospace is met.)

1. A processing and forming method of aluminum lithium alloy thick plate homogeneous fine grains is characterized in that:

the molding method comprises the following steps:

firstly, alloy ingot casting annealing: heating the ingot blank to 400-430 ℃ at a speed of less than or equal to 120 ℃/h, preserving heat for 3-12 h, then continuously heating to 470-500 ℃, preserving heat for at least 24h, cooling to below 180 ℃ along with the furnace, and then discharging from the furnace for air cooling;

secondly, directional fast forging cogging, namely rapidly directionally upsetting the annealed cast ingot along the axial direction (the casting and solidification direction of the cast ingot), and then performing fast forging, drawing and forming to form a square billet; wherein the initial forging temperature is not lower than 370 ℃, the final forging temperature is not lower than 340 ℃, and the temperature difference between the initial forging and the final forging is not more than 30 ℃; the cogging and upsetting speed is 65-200 mm/s, and the fast forging frequency is 50-80 times per minute; upsetting or drawing forging ratio is 2-4; after forging, air cooling to room temperature and then surface whitening;

thirdly, hot rolling and forming: firstly, rolling the square billet subjected to directional quick forging cogging at low temperature, wherein the cogging temperature is not higher than 320 ℃, and the rolling deformation is not lower than 25%; then high-temperature rolling is carried out, the initial rolling temperature is not lower than 370 ℃, and the rolling deformation is not lower than 40%.

Technical Field

The invention belongs to the field of metal material engineering, and particularly relates to a processing and forming method of aluminum-lithium alloy thick plate homogeneous fine grains.

Technical Field

The aluminum-lithium alloy is an aluminum alloy added with L i as a main alloy element, and has the characteristics of low density and high modulus due to the addition of lithium element, and has huge application prospect in the fields of high-speed rail, ships and the like which pursue light weight as a light-weight alloy material which can replace composite materials, magnesium alloys and 2-series/7-series high-strength aluminum alloys to manufacture light-weight structural members of aerospace aircraft parts.

At present, more than 20 grades of foreign third-generation aluminum-lithium alloys are applied in a large scale, the matched forming and processing technologies such as rolling, extruding, forging and the like are very mature, and a complete system of smelting, casting and forging and processing which is equal to the conventional aluminum alloy is formed. In the field of aerospace, a large amount of mature third-generation aluminum-lithium alloy is adopted abroad to replace the traditional 2-series/7-series high-strength aluminum alloy and high-cost composite materials and magnesium alloy with poor corrosion resistance, and the aluminum-lithium alloy material is applied to the manufacturing of fuselage skins, frames, lower-belly deck boards, floor beams and the like of military aircrafts and civil airliners and lightweight structural members such as fuel tanks and load cabin shells of aerospace aircrafts to obtain better effects of reducing weight and cost and prolonging service life.

At present, the research and development of the aluminum lithium alloy are mainly focused on the units such as southwest aluminum industry, Beijing aviation material research institute, Beijing nonferrous metal research institute and the like at home, and a large amount of basic research on the aluminum lithium alloy is also carried out in various colleges represented by the university of China and south and the university of northwest industry, and relates to multiple aspects such as smelting process, casting and forging process, processing process, heat treatment, laser welding, corrosion resistance and the like. Because the foreign blockade of the aluminum lithium alloy preparation and processing technology and the domestic relatively backward research on the aluminum lithium alloy basic research, a great deal of technical bottlenecks and problems which need to be solved urgently exist in the aspect of the aluminum lithium alloy key preparation and processing technology for high-end equipment in China, and the aluminum lithium alloy has low yield and unstable performance. At present, only southwest aluminum industry Limited liability companies develop and produce a small amount of aluminum-lithium alloy through a production, study and research cooperation mode in China, and the annual output is less than 100 tons, so that the dilemma that aluminum-lithium alloy materials seriously depend on import is caused.

Disclosure of Invention

Aiming at the technical background, the invention provides a processing and forming method of thick homogeneous fine grains of an aluminum lithium alloy material, which improves the toughness of the material and greatly reduces the anisotropy problem of the aluminum lithium alloy at the same time, and meets the requirement of manufacturing large-thickness aluminum lithium alloy with the thickness of more than 60mm for lightweight structural parts in the fields of aerospace and the like.

The invention is realized by the following technical scheme:

a processing and forming method of aluminum lithium alloy thick plate homogeneous fine grains comprises the following steps:

firstly, alloy ingot casting annealing: heating the ingot blank to 400-430 ℃ at a speed of less than or equal to 120 ℃/h, preserving heat for 3-12 h, then continuously heating to 470-500 ℃, preserving heat for at least 24h, cooling to below 180 ℃ along with the furnace, and then discharging from the furnace for air cooling;

secondly, directional fast forging cogging, namely rapidly directionally upsetting the annealed cast ingot along the axial direction (the casting and solidification direction of the cast ingot), and then performing fast forging, drawing and forming to form a square billet; wherein the initial forging temperature is not lower than 370 ℃, the final forging temperature is not lower than 340 ℃, and the temperature difference between the initial forging and the final forging is not more than 30 ℃; the cogging and upsetting speed is 65-200 mm/s, and the fast forging frequency is 50-80 times per minute; upsetting or drawing forging ratio is 2-4; after forging, air cooling to room temperature and then surface whitening;

thirdly, hot rolling and forming: firstly, rolling the square billet subjected to directional quick forging cogging at low temperature, wherein the cogging temperature is not higher than 320 ℃, and the rolling deformation is not lower than 25%; then high-temperature rolling is carried out, the initial rolling temperature is not lower than 370 ℃, and the rolling deformation is not lower than 40%.

Adopt above-mentioned technical scheme's beneficial effect:

after annealing, rapidly orienting, upsetting and cogging along the axial direction of an alloy ingot (the casting and solidification direction of the ingot), rapidly forging and drawing a square billet at high frequency, completely crushing a large amount of dendrites and equiaxed coarse crystals in an as-cast structure by a large deformation amount in a short time to obtain a fine and uniform grain structure and reduce metallurgical defects such as pores, porosity and the like, then adopting a process method combining low-temperature rolling and high-temperature rolling to solve the original grain boundary residue problem during thermal deformation of the aluminum-lithium alloy, refining the grain sizes and the tissue structures in the long direction (L), the transverse direction (L T) and the high direction (L S), further preparing thick plates with fine and uniform tissues and grains in all directions, simultaneously improving the strength and the ductility of the material by a fine grain strengthening method, obviously reducing the anisotropy of the aluminum-lithium alloy, preparing the thick plates with fine and uniform grains in all directions, improving the obdurability of the material, reducing the anisotropy of the aluminum-lithium alloy and effectively reducing the anisotropy of the aluminum-lithium alloy, and meeting the requirement of manufacturing of large-thickness aluminum-lithium alloy with the aerospace specification of more than 60 mm.

Drawings

FIG. 1 is a schematic view of the directional rapid forging of an aluminum lithium alloy ingot blank according to the present invention.

FIG. 2 is a microstructure diagram of aluminum lithium alloy in different directions;

in FIG. 2, (a) the long direction L, (b) the transverse direction L T, and (c) the high direction L S.

Detailed Description

The present invention will be described in further detail with reference to examples.