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Compound strengthening method of small hole in ultrahigh strength steel part

A technology for ultra-high-strength steel and parts, which is applied in the improvement field of surface strengthening methods, which can solve problems such as insufficient strengthening effect, high roughness, and scratches on the hole wall, and achieve the depth of the orifice extrusion strengthening layer and the feasibility of process implementation Good, the effect of improving fatigue resistance

Active Publication Date: 2011-02-02
AVIC BEIJING INST OF AERONAUTICAL MATERIALS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These two methods have their own advantages and disadvantages. Among them, the strengthening layer of small hole extrusion strengthening is deep and the strengthening effect is excellent, but extrusion is easy to cause scratches on the hole wall, and for parts with super large size and complex shape, the hole wall Squeeze is difficult, if not impossible
For example, the holes on the front of a certain type of aircraft frame and the main landing gear parts need to be strengthened. Due to two reasons, the conventional hole mandrel extrusion process cannot be implemented.
One of the reasons is: due to the large size and complex shape of the parts, it is difficult to apply the hole extrusion strengthening method in actual production; the second reason is: because the material strength is too high (σb> 1800MPa), the mandrel is subject to excessive restraint during the extrusion process, resulting in problems such as mandrel breakage, hole size out-of-tolerance and high roughness during the strengthening process
The small hole shot peening technology has strong engineering applicability, high efficiency, easy implementation, and less damage to the spray surface, but its strengthening effect is not as good as that of the extrusion strengthening method.

Method used

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  • Compound strengthening method of small hole in ultrahigh strength steel part
  • Compound strengthening method of small hole in ultrahigh strength steel part
  • Compound strengthening method of small hole in ultrahigh strength steel part

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] Example 1: Composite strengthening of Φ14mm holes

[0018] 1. Hole rounding

[0019] The orifice is manually rounded with a reamer, and the rounding radius is 1.0mm.

[0020] 2. Hole shot peening

[0021] Process selection:

[0022] (1) projectile

[0023] Projectile type: cast steel shot

[0024] Projectile size: φ0.4mm

[0025] (2) Shot peening method: Spray the hole wall directly by using the hair gun rotation and feeding method

[0026] (3) Shot peening intensity: 0.25A

[0027] (4) Shot peening coverage: 100%

[0028] (5) Spray angle (the angle between the nozzle and the tangent of the sprayed surface): 85°

[0029] 3. Orifice extrusion

[0030] Use a hydraulic press and a self-made orifice extrusion head to extrude and strengthen the orifice, and the extrusion load is 21MPa.

[0031] After using the above-mentioned process steps to strengthen the small hole on the tensile-tension fatigue sample with the middle opening of A-100 steel, the strengthening ef...

Embodiment 2

[0036] Example 2: Composite strengthening of Φ12mm holes

[0037] 1. Hole rounding

[0038] The orifice is manually rounded with a reamer, and the rounding radius is 1.0 mm.

[0039] 2. Hole shot peening

[0040] Process selection:

[0041] (1) projectile

[0042] Projectile type: cast steel shot

[0043] Projectile size: φ0.4mm

[0044] (2) Shot peening method: Spray the hole wall directly by using the hair gun rotation and feeding method

[0045] (3) Shot peening intensity: 0.20A

[0046] (4) Shot peening coverage: 100%

[0047] (5) Spray angle (the angle between the nozzle and the tangent of the sprayed surface): 85°

[0048] 3. Orifice extrusion

[0049] Use a hydraulic press and a self-made orifice extrusion head to extrude and strengthen the orifice, and the extrusion load is 21MPa.

[0050] After using the above-mentioned process steps to strengthen the small hole on the tensile-tension fatigue sample with the middle opening of A-100 steel, the strengthening e...

Embodiment 3

[0055] Example 3: Composite strengthening of Φ10mm holes

[0056] 1. Hole rounding

[0057] The orifice is manually rounded with a reamer, and the rounding radius is 1.0 mm.

[0058] 2. Hole shot peening

[0059] Process selection:

[0060] (1) projectile

[0061] Projectile type: cast steel shot

[0062] Projectile size: φ0.2mm

[0063] (2) Shot peening method: Spray the hole wall directly by using the hair gun rotation and feeding method

[0064] (3) Shot peening intensity: 0.20A

[0065] (4) Shot peening coverage: 100%

[0066] (5) Spray angle (the angle between the nozzle and the tangent of the sprayed surface): 85°

[0067] 3. Orifice extrusion

[0068]Using a hydraulic press, a self-made orifice extrusion head is used to extrude and strengthen the orifice, and the extrusion load is 16MPa.

[0069] After using the above-mentioned process steps to strengthen the small hole on the tensile-tension fatigue sample with the middle opening of A-100 steel, the strengthe...

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Abstract

The invention relates to the improvement of a surface strengthening method of a small hole in an ultrahigh strength steel part, belonging to surface strengthening technologies. The improved surface strengthening method is characterized by respectively conducting shot peening strengthening on a hole wall and extrusion strengthening on a hole mouth. The strengthening process comprises the following steps of: rounding the hole mouth; shot-peening the hole wall; and extruding the hole mouth. The invention combines the advantages of high surface quality reliability and good process implementation feasibility of the shot peening strengthening and the advantages of deep strengthening layer and good strengthening effect of the hole mouth extrusion, and the fatigue resistance of the small hole in the ultrahigh strength steel part is improved.

Description

technical field [0001] The invention belongs to the surface strengthening technology and relates to the improvement of the surface strengthening method of small holes on ultra-high-strength steel parts. Background technique [0002] Since aircraft landing gears often fail in the form of fatigue, the requirements for fatigue performance are relatively high. The strength of high-strength steel is very high, but it is highly sensitive to stress concentration, and its fatigue strength increases with K t The increase in value drops dramatically. And the fatigue cracks of the parts are mostly initiated in the stress concentration parts. Holes on parts are structural discontinuities, and are also typical stress concentration locations. How to improve the fatigue performance of parts with holes is a major practical problem in engineering applications. For the surface strengthening of small holes on parts, there are mainly two methods used in engineering, one is the extrusion stre...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D7/06
Inventor 高玉魁陆峰王强郭峰宋颖刚王欣
Owner AVIC BEIJING INST OF AERONAUTICAL MATERIALS
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