What are the material requirements for electromagnetic multi-way valves?

The material selection for an electromagnetic multi-way valve directly affects its pressure resistance, wear resistance, corrosion resistance, and service life. It requires comprehensive consideration of factors such as operating pressure, media characteristics, and environmental conditions.

The following are key material selection requirements and typical application solutions:

I. Core Component Material Requirements

1. Valve Body Material

Material Type | Characteristics | Applicable Scenarios

Ductile Cast Iron (QT500-7) | High strength (tensile strength ≥500MPa), good vibration damping, low cost | Medium and low pressure systems (≤35MPa), engineering machinery

Forged Steel (42CrMo) | Ultra-high strength (tensile strength ≥1000MPa), fatigue resistant, heat-treated and tempered | High pressure systems (42MPa+), metallurgical equipment

Aluminum Alloy (6061-T6) | Lightweight (density 2.7g/cm³), corrosion resistant, but lower pressure resistance (≤21MPa) | Aviation, mobile equipment

Stainless Steel (316L) | Resistant to acid and alkali/seawater corrosion, but high cost | Chemical industry, offshore platforms

Special Treatment:

Inner wall finishing: Ra≤0.4μm, reducing flow resistance.

Coating reinforcement: The valve body cavity is coated with a WC-Co coating (hardness HV1200+), resistant to particle erosion.

2. Valve Core and Sleeve

Material Combination | Advantages | Technical Parameters

20CrMnTi Carburized and Quenched + Hard Chrome Plating | Surface Hardness HRC60-62, Wear Resistance | Plating Thickness ≥0.03mm, Lifespan ≥1 million cycles

Stainless Steel (440C) + PTFE Coating | Corrosion Resistant and Low Coefficient of Friction (μ≤0.05) | Suitable for water-glycol media

Ceramic (Al₂O₃/ZrO₂) | Ultra-wear Resistant, Anti-adhesion, but Brittle | Used for high-pressure (≥60MPa) extreme working conditions

Precision Fit:

Valve Core and Valve Orifice Gap Control:

Ordinary Valve: 0.01~0.03mm

High-Precision Valve: ≤0.005mm (Requires temperature-controlled assembly)

3. Seals

Material | Temperature Range | Media Resistance | Lifespan

Nitrile Rubber (NBR) | -30℃~100℃ Mineral oil, water-oil emulsion: 500,000 cycles

Fluororubber (FKM): -20℃~200℃, acids and alkalis, synthetic ester oils: 1 million cycles

Polyurethane (PU): -40℃~80℃, high wear resistance, but not hydrolysis resistant: 300,000 cycles

PTFE + metal skeleton: -100℃~260℃, all hydraulic oils, highly corrosive media: 2 million cycles

II. Material Selection Strategy Based on Working Conditions

1. High-Pressure, Heavy-Duty Working Conditions (e.g., tunnel boring machines)

Valve Body: 42CrMo forged steel (quenched and tempered HB280-320)

Valve Core: 20CrMnTi carburized and quenched + laser-clad Stellite alloy

Seal: FKM + PTFE composite seal

2. 3. Corrosive Environments (e.g., Chemical Equipment)

Valve Body: 316L Stainless Steel (Passivated)

Valve Core: 17-4PH Precipitation Hardened Stainless Steel

Sealing: PTFE Full-Encapsulation Structure

4. Low-Temperature Environments (e.g., Ground Machinery)

Valve Body: QT400-18L (Low-Temperature Ductile Iron, -60℃ Impact Energy ≥12J)

Sealing: Silicone Rubber (MVQ) or Hydrogenated Nitrile Butadiene Rubber (HNBR)

5. Food/Pharmaceutical Equipment

Valve Body: 304 Stainless Steel (Electropolished Ra≤0.2μm)

Sealing: FDA-Certified EPDM Rubber

III. Application of Special Functional Materials

Antistatic Requirements:

Valve core with added carbon fiber (volume resistivity ≤10⁶Ω·cm) to prevent sparks from igniting dust.

Weight Reduction Design:

Titanium alloy (TC4) valve body, with the same strength as steel but 40% lighter.

Ultra-long lifespan:

The valve core uses a diamond-like carbon (DLC) coating, with a friction coefficient <0.02.

IV. Common Material Failures and Countermeasures

Failure Mode | Cause | Solution

Valve core scoring | Hard particles intruding into the gap | Replace with WC-Co coated valve sleeve + online filter

Seal swelling | Oil and material incompatibility | Replace with FKM or PTFE material

Valve body cracking | Casting defects or pressure shock | Use forged steel valve body + finite element stress optimization design

V. Future Material Trends

Smart materials: Shape memory alloy valve core, temperature-adaptive flow regulation.

Nanocomposite materials: Graphene-reinforced valve body, strength increased by 50%.

3D printing: Topology-optimized structure + gradient materials (e.g., copper-steel composite cooling channels).

Selection recommendation: A comprehensive evaluation is required, considering factors such as cost (materials account for 30%~50% of the total valve body cost), operating conditions, and maintenance cycle. Prioritize material options that are certified to ISO 4400/DIN 24340.