CN-121972780-A - Rolling auxiliary method for reducing residual stress of arc additive aluminum alloy

CN121972780ACN 121972780 ACN121972780 ACN 121972780ACN-121972780-A

Abstract

The invention discloses a rolling auxiliary method for reducing residual stress of an arc additive manufactured aluminum alloy component, and belongs to the technical field of metal additive manufacturing. The method is carried out online in the arc layer-by-layer deposition process, and comprises the steps of monitoring the temperature of an aluminum alloy cladding layer which is just deposited in real time, immediately utilizing a rolling device to apply mechanical pressure to the top surface of the cladding layer to roll when the temperature of the cladding layer is reduced to a preset rolling temperature window of 50-250 ℃, then continuing to deposit the next layer, utilizing a subsequent thermal cycle to induce the recrystallization of a rolling area of the previous layer, and repeating the process until the component is completed. According to the invention, the specific warm window is selected for rolling, so that the problems of high-temperature sticking roller and low-temperature cracking are avoided, the thermally induced tensile stress is directly counteracted by utilizing mechanical pressure, the crystal grains are refined by combining with subsequent thermal circulation, and the effective control of residual stress and deformation, the equiaxial conversion of coarse columnar crystal tissues and the improvement of internal compactness are synchronously realized.

Inventors

YUAN HAOMING
LIU XU
HE JUN
LIU BOXIAO
LI BOWEN

Assignees

河北工业大学

Dates

Publication Date: 20260505
Application Date: 20260209

Claims (9)

1. A rolling assist method for reducing residual stress in arc additive manufacturing aluminum alloy components, comprising the steps of: S1, forming an aluminum alloy cladding layer on a substrate or a deposited layer through arc cladding; S2, monitoring the temperature of the cladding layer in real time, and judging whether the temperature of the cladding layer is reduced to a preset rolling temperature window, wherein the rolling temperature window is 50-250 ℃; S3, when the temperature of the cladding layer is within the rolling temperature window, using a rolling device to apply mechanical pressure to the top surface of the cladding layer for rolling; S4, repeating the steps S1 to S3, depositing and rolling layer by layer, wherein the N layer is subjected to rolling treatment, then the N+1th layer is deposited, and heat input generated during the deposition of the N+1th layer acts on the N layer to induce the recrystallization of the rolling area of the N layer.
2. The rolling assistance method according to claim 1, wherein in step S1, the material of the aluminum alloy cladding layer is an al—cu-based, al—mg-based or al—si-based aluminum alloy.
3. The method according to claim 1, wherein in step S2, the temperature of the cladding layer is monitored in real time by an infrared thermometer or a thermocouple.
4. The method according to claim 1, wherein in step S3, the mechanical pressure is controlled by a rolling pressure or rolling depression amount, and the rolling pressure is 10 kN to 45 kN.
5. The method according to claim 1, wherein in step S3, the rolling reduction is 5% to 20% of the current cladding layer height.
6. The method according to claim 1, wherein in step S3, the rolling device includes a roller, a force applying mechanism for driving the roller, and a temperature monitoring assembly.
7. The method of claim 6, wherein the roller has cooling channels integrated therein.
8. The rolling assistance method according to claim 7, wherein the cooling channel is a water cooling channel or a liquid nitrogen cooling channel.
9. The method according to claim 6, wherein the roller has a flat bottom micro-convex profile.

Description

Rolling auxiliary method for reducing residual stress of arc additive aluminum alloy Technical Field The invention belongs to the technical field of additive manufacturing of metal materials, and particularly relates to a rolling auxiliary method for reducing residual stress of an arc additive aluminum alloy. Background Arc Additive Manufacturing (WAAM) technology has great potential in manufacturing complex structural members of aluminum alloy in the fields of aerospace, transportation and the like because of the advantages of high efficiency, low cost and suitability for manufacturing large-size members. However, the inherent high thermal conductivity, large coefficient of thermal expansion, etc. of aluminum alloy materials makes them very challenging during the repeated thermal cycles of WAAM cladding and rapid cooling, mainly in the following aspects: 1) The deposited layer is constrained by the rigidity of the solidified layer or substrate when it is cooled to shrink, resulting in a large non-uniform tensile residual stress, which can be as high as 60% to 100% of the yield strength of the material. The stress is easy to cause serious warping and cracking of the component and even peeling from the substrate, and is one of the core barriers for limiting WAAM technical popularization and application. 2) And WAAM in the process, the molten pool is quickly solidified along the heat radiation direction, so that coarse columnar crystals penetrating through a plurality of deposition layers are extremely easy to form. The mechanical properties such as strength and plasticity of the component in the deposition direction (Z direction) are obviously inferior to those in the scanning direction (X/Y direction), and the component has strong anisotropism, so that the requirement of complex stress working conditions is difficult to meet. 3) The aluminum alloy is easy to absorb hydrogen in the smelting and processing processes, and air holes are easy to form if the hydrogen is not enough to escape in the WAAM solidification process, so that the density, fatigue performance and mechanical reliability of the component are reduced. To cope with the above problems, the conventional method mainly adopts post-welding integral heat treatment or mechanical shape correction. Although the whole heat treatment can effectively reduce residual stress, the whole heat treatment cannot correct the macroscopic deformation, has high energy consumption and long period, and can possibly cause excessive growth or softening of crystal grains. The off-line mechanical hammering method has low efficiency, poor controllability and high noise, is difficult to realize automatic integration, and has negative influence on the surface quality of the component. Therefore, developing a process method capable of synchronously realizing stress control, tissue optimization and defect inhibition by online and real-time control WAAM process becomes a key technical problem to be solved in the field. Disclosure of Invention The invention aims to overcome the defects in the prior art, and provides a rolling auxiliary method for reducing residual stress of an arc additive aluminum alloy, which is used for obtaining an aluminum alloy component with low stress, high compactness and congruent axial crystals by introducing a specific rolling process, utilizing mechanical force to induce plastic deformation to counteract thermally induced tensile stress, crushing coarse grains and pressing air holes. Accordingly, it is an object of the present invention to provide a crush assist method for reducing residual stress in arc additive manufacturing aluminum alloy components, comprising the steps of: S1, forming an aluminum alloy cladding layer on a substrate or a deposited layer through arc cladding; S2, monitoring the temperature of the cladding layer in real time, and judging whether the temperature of the cladding layer is reduced to a preset rolling temperature window, wherein the rolling temperature window is 50-250 ℃; S3, when the temperature of the cladding layer is within the rolling temperature window, using a rolling device to apply mechanical pressure to the top surface of the cladding layer for rolling; S4, repeating the steps S1 to S3, depositing and rolling layer by layer, wherein the N layer is subjected to rolling treatment, then the N+1th layer is deposited, and heat input generated during the deposition of the N+1th layer acts on the N layer to induce the recrystallization of the rolling area of the N layer. In step S1, the material of the aluminum alloy cladding layer is an al—cu-based, al—mg-based or al—si-based aluminum alloy. Further, in step S2, the temperature of the cladding layer is monitored in real time by an infrared thermometer or a thermocouple. Further, in step S3, the mechanical pressure is controlled by the rolling force or the rolling depression amount, and the rolling force is 10 kN to 45 kN. Further, in step S3, the rolling pressing a