Aluminium Casting Alloy LM25
This alloy conforms to BS 1490:1988 LM25. Castings are standardised in the cast (M) condition, the precipitation treated (TE) condition, the solution treated and stabilised (TB7) condition and the fully heat treated (TF) condition.Mechanical Properties LM25-M LM25-TE LM25-TB7 LM25-TF 0.2% Proof Stress (N/mm2) 80-100 80-100 120-150 130-200 80-110 90-110 200-250 220-260 Tensile Strength (N/mm2) 130-150 160-200 150-180 190-250 160 230 230-280 280-320 Elongation (%) 2 3 1 2 2.5 5 - 2 Impact resistance Izod (Nm) - - - - - - - - Brinell Hardness 55-65 55-65 70-75 75-95 65-75 65-75 90-110 90-110 Modulus of Elasticity (x103 N/mm2) 71 71 71 71 71 71 71 71 Shear Strength (N/mm2) - - 140 - - - 180 250
Strength at elevated temperatures
The tensile properties of LM25 alloy at elevated temperatures are influenced by the condition (heat treatment) of the castings and the duration at the elevated temperature. On short term testing e.g. 30 minutes at temperature, the properties fall only slowly and uniformly up to about 200 deg C, at which temperature the strength of LM25-TF is reduced by about 20%. Very prolonged heating, e.g. 10,000 hours, results in a sharp loss of strength at about 135 deg c. At 200 deg C the strength of LM25-TF is less than half of that at room temperature. There is therefore no advantage to be gained by heat treatment, if the component is to be used at temperatures above about 130 deg C, for extended periods of time.
Physical Properties
Coefficient of Thermal Expansion (per °C @ 20-100°C) 0.000022 Thermal conductivity (cal/cm2/cm/