EN AC-48000 T5 vs. T6 | AlSi12CuNiMg T5 vs T6

Property	T5 Condition	T6 Condition	Main Difference
Heat Treatment Condition	Cooled from elevated-temperature shaping process and artificially aged	Solution heat-treated and artificially aged	T6 includes solution treatment → stronger structure
Standard Designation	EN AC-48000 / EN AC-Al Si12CuNiMg	EN AC-48000 / EN AC-Al Si12CuNiMg	Same alloy, different heat treatment
Typical Applications	Wheels, axle housings, differential housings, intake manifolds, fuel pumps	Wheels, axle housings, differential housings, intake manifolds, fuel pumps	Same applications
Density	2.65–2.71 g/cm³	2.65–2.71 g/cm³	Same
Young’s Modulus	70.6–73.4 GPa	70.6–73.4 GPa	Same
Yield Strength	176–194 MPa	234–258 MPa	T6 is significantly higher
Tensile Strength	200–220 MPa	266–294 MPa	T6 is much stronger
Specific Strength	65.5–72.5 kN·m/kg	87.2–96.3 kN·m/kg	T6 better strength-to-weight ratio
Elongation	1–1.2%	1–1.2%	Same
Compressive Strength	176–194 MPa	228–252 MPa	T6 higher
Flexural Strength	185–204 MPa	240–264 MPa	T6 higher
Hardness (Vickers)	100–110 HV	108–119 HV	T6 harder
Fatigue Strength (10⁷ cycles)	100–116 MPa	100–116 MPa	Nearly same
Fracture Toughness	18–20.5 MPa√m	18–20.5 MPa√m	Same
Maximum Service Temperature	170–200°C	170–200°C	Same
Thermal Conductivity	130–165 W/m·°C	130–165 W/m·°C	Same
Thermal Shock Resistance	121–136°C	161–181°C	T6 significantly better
Electrical Conductivity	24.3–45.4 %IACS	24.3–45.4 %IACS	Same
Machining Speed	76.2 m/min	61 m/min	T5 easier to machine
Weldability	Excellent	Excellent	Same
Corrosion Resistance	Good / susceptible to SCC in chloride	Good / susceptible to SCC in chloride	Same
Fresh Water Resistance	Excellent	Excellent	Same
Salt Water Resistance	Acceptable	Acceptable	Same
Strong Alkalis Resistance	Unacceptable	Unacceptable	Same
Embodied Energy	179–197 MJ/kg	179–197 MJ/kg	Same
Recycling CO2 Footprint	2.42–2.68 kg/kg	2.42–2.68 kg/kg	Same
Main Advantage	Better machinability and lower cost processing	Higher strength and hardness	Depends on design priority
Best Use Case	When machining ease and cost matter more	When maximum strength is required	Selection depends on performance target

Quick Selection Guide

If You Need…	Choose
Higher mechanical strength	T6
Better hardness	T6
Better thermal shock resistance	T6
Easier machining	T5
Lower processing cost	T5
Better fatigue performance	Both similar
Better weldability	Both same

T5 is preferred when easier machining and lower production cost are important.
T6 is preferred when higher strength, higher hardness, and better thermal shock resistance are required.

For structural and high-load automotive applications, T6 is generally the stronger and more premium option, while T5 offers better manufacturing efficiency.