Views: 0 Author: Site Editor Publish Time: 2025-10-30 Origin: Site
As a high-strength pearlite-based gray cast iron, HT250 has become the preferred material for heavy-duty fields due to its excellent compressive strength, wear resistance, and shock absorption. Its key characteristics include:
Mechanical properties: Room temperature tensile strength ≥250 MPa (high-quality products can reach over 369 MPa), Brinell hardness around 200-240 HB, suitable for continuous high-load working conditions.
Thermal stability: Low coefficient of thermal expansion (10–13.6×10⁻⁶/°C) and good microstructural stability at high temperatures. However, its strength will drop to 169 MPa at 600°C, requiring alloying (e.g., adding chromium, copper) to improve high-temperature performance.
Economy: Material cost is about 5000 yuan/ton, with mature casting processes suitable for mass production.
Cast iron cylinder block
A380 is an aluminum-silicon-copper die-casting alloy focusing on lightweight and high thermal conductivity, but its strength disadvantage needs to be compensated through strengthening processes (e.g., forging, cylinder liner inlay):
Mechanical properties: Tensile strength of 310-324 MPa, comparable to HT250, but elongation is only 1-2% and Brinell hardness around 100 HB, with poor toughness.
Thermophysical properties: High coefficient of thermal expansion (21–23.5×10⁻⁶/°C), but thermal conductivity (96-120 W/m·K) is about twice that of cast iron, which can significantly reduce engine thermal load.
Wear resistance defect: Inherent poor wear resistance, requiring surface treatment (e.g., plasma spraying) or inlaying cast iron cylinder liners to solve.
Aluminium alloy cylinder block
Performance Indicator | Gray Cast Iron HT250 | Aluminum Alloy A380 | Advantage/Disadvantage Analysis |
Density (g/cm³) | 7.2–7.3 | 2.7 | Aluminum alloy has significant lightweight advantage |
Tensile Strength (MPa) | ≥250 | 310–324 | Comparable, but aluminum alloy requires strengthening processes |
Hardness (HB) | 200–240 | ~100 | Cast iron has better wear resistance |
Coefficient of Thermal Expansion (10⁻⁶/°C) | 10–13.6 | 21–23.5 | Cast iron has better thermal stability |
Thermal Conductivity (W/m·K) | 45–55 | 96–120 | Aluminum alloy leads in heat dissipation efficiency |
Wear Resistance | Good | Poor, requires special treatment | Cast iron is more suitable for high-wear environments |
Cost | Low (about 5000 yuan/ton) | Higher (material + processing) | Cast iron has economic advantages |
Core advantages: Extremely high compressive strength, deformation resistance, and wear resistance, suitable for continuous high-load environments such as mining machinery, heavy-duty trucks, and generator sets.Typical scenarios:
Diesel engine cylinder blocks (e.g., construction machinery, marine power)
Machine tool beds, gearboxes, and other components requiring high shock absorptionProcurement keywords: "Heavy-duty diesel engine cast iron cylinder block", "high-toughness frost-crack-resistant cast iron cylinder head" (for extremely cold environments).
Cast iron engine block for heavy-duty truck
Core advantages: About 30% lighter than cast iron, and thermal conductivity improves fuel economy, suitable for passenger cars, high-performance sedans, and light commercial vehicles.Strengthening requirements: Forging process or cast iron cylinder liner installation is required to ensure strength; corrosion-resistant coating models should be selected for coastal/high-corrosion areas.Procurement keywords: "High-temperature resistant forged aluminum alloy cylinder head", "lightweight cylinder block (with cylinder liner)".
Aluminium alloy cylinder block
High-temperature/corrosion environments: Cast iron needs to add alloying elements such as chromium and nickel to improve heat resistance; aluminum alloy requires anodizing or composite coatings (e.g., ceramic coatings).Extremely cold environments: Cast iron needs to control phosphorus content to prevent low-temperature brittle fracture; aluminum alloy needs to optimize silicon content to avoid cold brittleness.
Cast iron repair: Welding requires preheating to above 500°C to prevent cracks, and nickel-based welding materials should be used to ensure bonding strength.Aluminum alloy treatment: T6 heat treatment (solution treatment + aging) can increase strength to over 300 MPa, but temperature must be strictly controlled to prevent overheating.
Cylinder head bolt torque: Must follow manufacturer's specifications (e.g., Volkswagen EA888 adopts the "40 Nm + 90° + 90°" torque-angle method) to avoid seal failure.Sealing materials: High-temperature resistant sealant (e.g., Three Bond 1282B) should be used for cast iron joint surfaces, and elastic gaskets should be matched with aluminum alloy to adapt to thermal expansion.
Consideration Dimension | Scenarios for Prioritizing Cast Iron HT250 | Scenarios for Prioritizing Aluminum Alloy A380 |
Load Intensity | Continuous heavy load (＞10-year service life) | Intermittent medium-low load (pursuing fuel economy) |
Weight Sensitivity | Low | High (needing weight reduction of more than 30%) |
Heat Dissipation Demand | Conventional cooling system can meet | High-efficiency heat dissipation required (e.g., turbocharged models) |
Cost Control | Limited initial budget, low maintenance cost | Willing to pay a premium for lightweight |
Environmental Adaptability | Extremely cold/high-corrosion environments (after special treatment) | Mild environments or with protective coatings |
The selection of cast iron HT250 and aluminum alloy A380 is essentially a balance of strength, weight, cost, and heat dissipation:
HT250 focuses on strength and durability, suitable for long-term high-load scenarios such as heavy industry and transportation;
A380 has advantages in lightweight and thermal management, dominating passenger cars and energy-saving priority fields, but needs to compensate for its mechanical performance shortcomings through processes.
In extreme environments, both need to achieve adaptive upgrades through alloy design or surface treatment, and maintenance processes must strictly follow material characteristics and manufacturer specifications.
