A413 vs A380 -When Pressure Tightness Justifies the Alloy Switch

A380 is the general-purpose choice: best balance of strength, castability, machinability, and cost. A413 is the pressure-tight specialist: slightly weaker, slightly more expensive, but with significantly better internal soundness. Choose based on whether pressure tightness is a design requirement.

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Comparison

Parameter	A413	A380
Silicon	11.0-13.0% (near-eutectic)	7.5-8.5%
Copper	1.0% max	3.0-4.0%
Tensile strength	290 MPa	317 MPa
Yield strength	145 MPa	159 MPa
Thermal conductivity	121 W/m·K	96 W/m·K
Pressure tightness	Best -near-eutectic microstructure	Good
Porosity level (equivalent process)	Lower -finer solidification	Moderate
Machinability	Good	Excellent
Cost premium	~3-%	Baseline

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Why A413 Has Lower Porosity

At A413's near-eutectic composition (12% Si, eutectic at 12.6%), solidification occurs with minimal dendrite formation -the microstructure is finer, shrinkage is lower, and inter-dendritic porosity channels are smaller and less interconnected. The result: reliably lower porosity per unit volume versus A380 in the same geometry and process conditions.

For a hydraulic manifold, the difference between Class 2 and Class 4 porosity (ASTM E505) can be the difference between passing and failing a 200 bar leak test.

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When to Switch from A380 to A413

Switch to A413 when:

• Rated working pressure exceeds 80-100 bar and impregnation is not acceptable
• Helium leak test is required (<10^-5 mbar·L/s)
• Thermal conductivity is the design driver (121 vs 96 W/m·K -26% better)
• Internal soundness certification to ASTM E505 Class 1- is required

A380 is adequate when:

• No pressure tightness requirement
• Maximum tensile strength needed (A380: 317 vs A413: 290 MPa)
• Extensive CNC machining planned (A380 better machinability)
• General structural or enclosure application

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The Cost Calculation

A413 costs ~3-% more per kg than A380. On a 1 kg casting at $3.00/kg material: $0.09-0.15/part premium. If this switch eliminates:

• Pressure test rework cycles: $1-/part
• VPI impregnation post-process: $1-/part
• Field leakage warranty returns: $20-100/part returned

The alloy switch pays for itself on the first quality event it prevents.

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Hydraulic alloy selection: yaoqingpu1983@gmail.com | +86 138 1403 4409