Comparison of Semi-Solid Magnesium Alloy Processing and Conventional Magnesium Alloy Processing

There are six points about Comparison of Semi-Solid Magnesium Alloy Processing and Conventional Magnesium Alloy Processing.

I. Comparison of Forming Processes

  1. Process Flow
    o Conventional magnesium alloy die casting: Direct die casting of liquid metal
    o Semi-solid magnesium alloy forming: Thixoforming/rheoforming of metal slurry (solid-liquid two-phase)
  2. Melt Temperature
    o Conventional magnesium alloy die casting: 650–680°C (fully liquid)
    o Semi-solid magnesium alloy forming: 580–620°C (solid fraction: 40–60%)
  3. Injection Speed
    o Conventional magnesium alloy die casting: 30–60 m/s (high-speed filling)
    o Semi-solid magnesium alloy forming: 0.5–5 m/s (low-speed laminar filling)
  4. Die Temperature
    o Conventional magnesium alloy die casting: 200–250°C
    o Semi-solid magnesium alloy forming: 150–200°C
  5. Forming Pressure
    o Conventional magnesium alloy die casting: 40–100 MPa
    o Semi-solid magnesium alloy forming: 10–50 MPa
  6. Key Equipment
    o Conventional magnesium alloy die casting: Standard die casting machine
    o Semi-solid magnesium alloy forming: Specialized semi-solid forming machine (equipped with slurry preparation system)
  7. Process Advantages
    o Semi-solid process: Reduced gas entrapment defects (porosity <1% vs. 3–5% for conventional); 30% longer die life
    o Conventional die casting: Shorter production cycle (20 seconds/part vs. 30–50 seconds/part for semi-solid)

Please also review the below HPDC (high pressure die casting) video and get more information you will need :

More video of Semii-Solid Thixomolding :

II. Comparison of Material Properties

  1. Tensile Strength
    o Conventional magnesium alloy (AZ91D): 230–250 MPa
    o Semi-solid magnesium alloy (AZ91D-SS): 260–300 MPa
  2. Elongation
    o Conventional magnesium alloy (AZ91D): 3–5%
    o Semi-solid magnesium alloy (AZ91D-SS): 8–12%
  3. Fatigue Strength (10⁷ cycles)
    o Conventional magnesium alloy (AZ91D): 80–90 MPa
    o Semi-solid magnesium alloy (AZ91D-SS): 110–130 MPa
  4. Corrosion Resistance (Salt Spray Test)
    o Conventional magnesium alloy (AZ91D): Corrosion appears after 48 hours
    o Semi-solid magnesium alloy (AZ91D-SS): No significant corrosion after 120 hours
  5. High-Temperature Strength (150°C)
    o Conventional magnesium alloy (AZ91D): 35% reduction
    o Semi-solid magnesium alloy (AZ91D-SS): 15% reduction
  6. Surface Roughness (Ra)
    o Conventional magnesium alloy (AZ91D): 1.6–3.2 μm
    o Semi-solid magnesium alloy (AZ91D-SS): 0.8–1.6 μm
  7. Mechanism of Property Improvement
    o Semi-solid forming utilizes a non-dendritic microstructure (globular grains) to achieve grain refinement, reduce porosity, and control oxide inclusions.

III. Production Cost Comparison

  1. Raw Material Costs
    o Traditional Die Casting: Low (direct melting)
    o Semi-solid Forming: High (requires slurry preparation equipment; 15% higher energy consumption)
  2. Equipment Investment
    o Traditional Die Casting: 5–8 million RMB (3,000-ton die-casting machine)
    o Semi-solid Forming: 12–20 million RMB (specialized semi-solid system)
  3. Mold Wear/Lifespan
    o Traditional Die Casting: 80,000–100,000 cycles
    o Semi-solid Forming: 120,000–150,000 cycles
  4. Yield Rate
    o Traditional Die Casting: 85–90%
    o Semi-solid Forming: 95–98%
  5. Post-processing Costs
    o Traditional Die Casting: High (requires deburring, repair welding)
    o Semi-solid Forming: Low (near-net-shape forming)
  6. Economic Break-even Point
    o Traditional Process: Suitable for high-volume, simple parts (>100,000 units/year)
    o Semi-solid Forming: High-value-added precision parts (aerospace, medical devices)

IV. Differences in Typical Applications

  1. Automotive Sector
    o Traditional magnesium alloy applications: Structural bracket components
    o Semi-solid magnesium alloy applications: Engine mounting brackets, turbocharger housings
  2. 3C Electronics Sector
    o Traditional magnesium alloy applications: Standard casings
    o Semi-solid magnesium alloy applications: Ultra-thin foldable screen hinges (0.3 mm thickness)
  3. Aerospace Sector
    o Traditional magnesium alloy applications: Non-load-bearing components
    o Semi-solid magnesium alloy applications: Landing gear doors, precision housings for flight control systems
  4. Medical Device Sector
    o Traditional magnesium alloy applications: Equipment casings
    o Semi-solid magnesium alloy applications: Orthopedic implants, minimally invasive surgical instruments

V. Comparison of Technical Bottlenecks

  1. Material Limitations
    o Conventional Die Casting: Poor high-temperature performance; prone to corrosion
    o Semi-solid Forming: Difficulty in controlling raw material slurry stability (requirement of ±2°C)
  2. Process Control
    o Conventional Die Casting: Defects such as gas entrapment and shrinkage porosity
    o Semi-solid Forming: Insufficient precision in real-time monitoring of solid fraction
  3. Environmental Issues
    o Conventional Die Casting: Use of SF6 greenhouse gas
    o Semi-solid Forming: High cost of nitrogen shielding during the slurry preparation process
  4. Standardization
    o Conventional Die Casting: Mature (comprehensive ASTM/GB standards)
    o Semi-solid Forming: Lack of unified process specifications

VI. Future Development Trends

  1. Hybrid Process Innovation
    o Semi-solid + Squeeze Casting: Enhances performance of thick-walled parts (wall thickness >15mm)
    o Semi-solid + 3D Printing: Enables forming of functionally graded materials
  2. Low-Cost Slurry Preparation Technology
    o Mechanical stirring replacing electromagnetic stirring (40% cost reduction)
    o Development of novel thixotropic agents (reducing slurry preparation time to under 5 minutes)
  3. Intelligent Control
    o Machine vision-based online solid fraction monitoring
    o Digital twin-based process optimization systems
    Summary and Recommendations
    • Prioritize semi-solid processing for: High-precision complex parts, fatigue-resistant critical components, and thin-walled precision parts
    • Retain traditional processes for: Low-cost mass production and structural components with moderate performance requirements
    • As the localization of semi-solid processing equipment accelerates, costs are decreasing at an average annual rate of 7%; large-scale replacement of traditional processes in the automotive sector is projected by 2030.