Shot Peening Boosts Metal Durability in Surface Treatment Breakthrough

In modern industrial applications, the importance of surface engineering technology has become increasingly prominent. The performance, lifespan, and appearance of products largely depend on their surface characteristics. Various surface treatment methods have emerged to improve material properties such as wear resistance, corrosion resistance, fatigue strength, and adhesion. Shot peening, as a mature and efficient surface engineering technology, has found extensive applications across multiple industries.

Shot peening, also known as shot blasting, is a cold working process that bombards a workpiece surface with high-velocity abrasive particles (media) to induce plastic deformation, thereby altering the surface's physical and mechanical properties. Unlike sandblasting, which primarily focuses on cleaning and removing surface contaminants, shot peening aims to strengthen surfaces, improving fatigue strength and stress corrosion resistance.

The core principle involves high-speed media particles impacting the surface to create plastic deformation. Each impact forms a microscopic indentation, generating compressive stress around the indentation and tensile stress at its base. When impact force is sufficient, surface material undergoes plastic deformation, forming a residual compressive stress layer.

This residual compressive stress layer is crucial for enhancing component performance. It counteracts tensile stresses during service, delaying crack initiation and propagation, thereby improving fatigue strength and stress corrosion resistance. Additionally, shot peening enhances surface hardness, wear resistance, and corrosion resistance.

Shot peening effectiveness depends on multiple parameters:

• Media type and size: Material, hardness, shape, and size affect impact energy and deformation. Common media include steel shot, ceramic beads, glass beads, and cast iron shot.
• Velocity: Determines kinetic energy, influencing impact force and plastic deformation.
• Impact angle: Affects force direction and distribution, typically near-perpendicular.
• Duration/coverage: Determines impact frequency and area coverage percentage.
• Intensity: Measured using Almen strips to quantify plastic deformation.

This advanced surface engineering technique offers significant benefits:

• Enhances fatigue strength by inhibiting crack initiation/propagation
• Improves stress corrosion resistance
• Increases surface hardness and wear resistance
• Modifies surface roughness for better coating adhesion
• Mitigates residual tensile stresses from welding/heat treatment
• Applicable to metals and non-metals (steel, aluminum, titanium, ceramics, plastics)
• Adjustable parameters for material-specific requirements
• Automation-compatible for consistent results
• Environmentally friendly dry process

Shot peening serves diverse industries requiring enhanced surface properties:

• Aerospace: Critical components like turbine blades, landing gear, and airframe structures
• Automotive: Engine components (connecting rods, crankshafts), suspension springs
• Manufacturing: Gears, shafts, springs, dies
• Marine: Hull structures, propellers, shaft systems
• Medical: Implants (joint replacements, dental fixtures)

Standard shot peening involves:

1. Surface preparation (cleaning)
2. Equipment/media selection
3. Parameter optimization
4. Treatment execution
5. Quality inspection (roughness, hardness, residual stress)
6. Post-processing (cleaning, coating)

Equipment types include:

• Wheel blast machines (high-volume production)
• Air blast systems (flexible for small batches)
• Wet blast units (reduced dust, improved finish)
• CNC-controlled machines (precision automation)

Media options range from steel shot (general use) to ceramic beads (specialized applications) and organic media (environmentally sensitive applications).

Effective quality control monitors media condition, equipment parameters, and surface outcomes. Emerging developments include:

• Smart automation with computerized controls
• Digital process modeling
• Eco-friendly media/equipment
• Hybrid processes combining multiple techniques
• Micro-scale applications for precision components

Selecting appropriate shot peening solutions requires evaluating:

• Material compatibility
• Performance requirements
• Production volume
• Cost-effectiveness
• Environmental compliance