Gradient Nanostructure Surface Layering for High-Melting-Point Metals

Solution Overview

Problem

Nanostructured materials exhibit increased strength and hardness but compromised plasticity and toughness, limiting their application in extreme service environments, and existing surface engineering techniques struggle to achieve optimal gradient nanostructures in metal workpieces with high melting points.

Innovation Solution

A combined method involving laser shock peening (LSP) to induce deep plastic deformation followed by surface mechanical attrition treatment (SMAT) for nanocrystallization, optimizing the gradient nanostructure in the surface layer of metal workpieces, specifically using LSP with an aluminum absorption layer and SMAT with controlled vibration frequency and ball diameter to achieve desirable layer thickness and microstructure distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If laser shock peening is used to induce deep plastic deformation, then the depth of residual stress layer is increased, but gradient nanostructure cannot be achieved in high melting point metals

Engineering Contradiction:

Improvedepth of residual stress layerVSAvoidgradient nanostructure formation

Core Design Contradiction:

Length of stationary objectVSManufacturing precision

Solution Approach 1:

The patent combines laser shock peening (LSP) and surface mechanical attrition treatment (SMAT) into a sequential two-step process. LSP first creates deep plastic deformation and residual stress layer, then SMAT follows to refine the microstructure into gradient nanostructure. This merging of two techniques resolves the contradiction by achieving both deep treatment depth and precise nanostructure control in high melting point metals.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Laser shock peening is performed first as a preliminary action to create deep plastic deformation and prepare the substrate. This preliminary deformation layer then serves as the foundation for subsequent SMAT processing, enabling SMAT to efficiently form gradient nanostructure. The preliminary action of LSP extends the effective depth before the final nanostructure formation.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If surface mechanical attrition treatment is used for nanocrystallization, then gradient nanostructure is achieved, but treatment depth is limited

Engineering Contradiction:

Improvegradient nanostructureVSAvoidtreatment depth

Core Design Contradiction:

Manufacturing precisionVSLength of stationary object

Solution Approach 1:

Laser shock peening is performed first as a preliminary action to create deep plastic deformation and prepare the substrate. This preliminary deformation layer then serves as the foundation for subsequent SMAT processing, enabling SMAT to efficiently form gradient nanostructure. The preliminary action of LSP extends the effective depth before the final nanostructure formation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent combines laser shock peening (LSP) and surface mechanical attrition treatment (SMAT) into a sequential two-step process. LSP first creates deep plastic deformation and residual stress layer, then SMAT follows to refine the microstructure into gradient nanostructure. This merging of two techniques resolves the contradiction by achieving both deep treatment depth and precise nanostructure control in high melting point metals.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of manufacture

If conventional homogeneous materials are used, then manufacturing simplicity is maintained, but performance requirements in extreme service environments cannot be met

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidperformance in extreme service environments

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies local quality by creating a gradient nanostructure only in the surface layer of the metal workpiece, while the bulk material maintains its original homogeneous structure. This localized treatment provides enhanced performance (strength, hardness, wear resistance) where it is most needed in extreme service environments, while maintaining manufacturing simplicity for the bulk material.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies partial action by treating only the surface layer of the metal workpiece with the combined LSP-SMAT process, rather than treating the entire material. This partial treatment achieves the necessary performance enhancement for extreme service environments while avoiding the complexity and cost of treating the entire bulk material.

Inventive Principle:

Principle #16Partial or excessive action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The method effectively enhances the overall mechanical properties of metal workpieces by achieving a balance between strength and plasticity, improving fatigue life and wear resistance, and optimizing surface roughness and quality, while reducing post-treatment costs.

Implementation Method 1

the laser beam is absorbed by an absorption layer after it passes through a confinement layer

Methodology Applied

Scientific EffectLaser absorption: Absorption (EM radiation)

Implementation Method 2

the absorption layer obtains energy and undergoes explosive gasification and evaporation, and produces high-temperature and high-pressure plasma

Methodology Applied

Scientific EffectLaser-induced plasma: Plasma

Implementation Method 3

Laser shock peening (LSP) is a new surface strengthening technique, which mainly employs laser irradiation with high-peak power density (>10^9 W/cm^2) in the form of short pulses

Methodology Applied

Scientific EffectLaser shock peening: Laser Peening

Implementation Method 4

under a confinement effect of the outer confinement layer, the plasma forms a high-pressure shock wave, which is propagated into the material

Methodology Applied

Scientific EffectShock wave: Shock Wave

Implementation Method 5

the surface layer of the material has plastic deformation under a force effect of the shock wave

Methodology Applied

Scientific EffectPlastic deformation: Plasticity

Implementation Method 6

the relative micro-friction between the balls and the metal material generates heat and causes increased temperature of the surface layer of the metal

Methodology Applied

Scientific EffectFriction heating: Friction

Implementation Method 7

Surface mechanical attrition treatment (SMAT) is the most effective process for forming gradient nanostructure in the surface layer of a metal

Methodology Applied

Scientific EffectSurface mechanical attrition treatment:

Implementation Method 8

Gradient nanostructured materials exhibit excellent overall strength-plasticity performance. Gradient nanostructured magnesium alloys formed on the basis of plastic deformation incorporate the properties of nanograins and the properties of coarse grains

Methodology Applied

Scientific EffectGradient nanostructure formation:

Data Source

PatentUS11447837B2Combined fabricating method for gradient nanostructure in surface layer of metal workpiece

Publication Date: 2022.09.20 JIANGSU UNIV

AI summary

Provided is a combined fabricating method for gradient nanostructure in the surface layer of a metal workpiece. A plastic deformation layer in great depth is induced by laser shock peening, then the surface of the metal workpiece is nanocrystallized by surface mechanical attrition treatment, and finally a gradient nanostructure is obtained in the surface layer of the metal workpiece with desirable layer thickness and optimized micro-structure distribution.