A Laser Shock Strengthening Method for Small Hole Welds of Aircraft Engine Fan Casing

Abstract

The invention relates to the technical field of aero-engines, in particular to a laser shock strengthening method for small hole welds in an aero-engine fan casing, including detection of welds before strengthening, double-sided sequential strengthening of thin-walled weld structures, and flaw detection hole structure Next to the partition strengthening process, the laser shock path of different blocks and the laser energy gradient distribution process and the design of the casing fixture. In the present invention, a special fixture that can realize three-stage casing clamping is designed, and double-sided laser shock strengthening is carried out on the small hole weld zone and heat affected zone according to the process of partition variable parameter strengthening, so as to eliminate the residual stress of small hole chamfer welding, And the residual compressive stress is prefabricated to effectively improve the fatigue resistance and stress corrosion resistance of the welded parts.

Description

technical field [0001] The invention relates to the technical field of aero-engines, in particular to a laser shock strengthening method for small hole welds in an aero-engine fan casing. Background technique [0002] The aero-engine fan casing is equipped with a flaw detection hole, and the hole structure is connected with the casing by argon arc welding. Due to the chamfers in the weld area of ​​the flaw detection hole, the structure is relatively complex, and the aero-engine has high requirements on the surface integrity of the components. There are certain difficulties in using traditional welding stress relief methods such as heat treatment, overload treatment, and hammering. According to statistics, during the use of a certain type of engine, many crack failures occurred in the weld seam of the flaw detection hole of the fan case, which seriously affected the flight safety. [0003] Laser shock strengthening is an important technical means to improve the high-cycle f...

AI Technical Summary

Problems solved by technology

Due to the chamfers in the weld area of ​​the flaw detection hole, the structure is relatively complex, and the aero-engine has high requirements on the surface integrity of the components

There are certain difficulties in using traditional welding stress relief methods such as heat treatment, overload treatment, and hammering

According to statistics, during the use of a certain type of engine, many faults occurred in the welding seam cracks of the fan case flaw detection hole, which seriously affected flight safety.

[0003] Laser shock strengthening is an important technical means to improve the high-cycle fatigue performance of aero-engine components. It has been used to strengthen aero-engine blades, ducts, engine disks, fastening holes and other important engine components and parts. The basic principle is to use short pulse width ( ns level), high power (>1GW / cm2) laser-induced plasma shock wave (>1GPa) mechanical effect, causing plastic deformation of metal materials with ultra-high strain rate (>106 / s), significantly refining grains, forming residual The compressive stress layer and high-density dislocation structure can improve the fatigue performance of the material. The material performance of the argon arc welding seam is good, and there is basically no internal stress, but there are hundreds of MPa residual tensile stress in the heat-affected zone, which can be eliminated after vacuum heat treatment. After internal stress, the grains in the heat-affected zone remain coarse, and the fatigue performance is poor

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