Pressure diecasting Aluminium alloy.
L M 2 is essentially a pressure diecasting alloy conforming to
BS 1490 1988, this alloy is often specified as an alternative
LM 24 in pressure diecasting applications.
LM 2 is a general-purpose alloy suitable for the manufacture
of almost any diecast part. It is often specified on large volume
diecast applications in preference to LM 24 because of its lower
density. By implication this means that applications for this alloy
are quite wide and varied. Service conditions which dictate
high corrosion resistance or higher than usual ductility would
normally require an alternative alloy.
The chemistry present has a marked effect on the
mechanical properties achieved; low levels of copper,
nickel and manganese reduce the strength at temperatures
above 2500 C. For this reason it is advisable to restrict the
service conditions to a maximum of 1500 C. Corrosion
resistance is inferior to LM 6 but use in normal atmospheric
conditions is acceptable. Anodising of LM 2 castings is possible,
but only on decorative finishes, as a grey film will result.
LM 2 castings are not normally heat-treated but annealing
is possible to improve ductility.The high silicon levels present
in this alloy mean that machining can be marginally difficult and
result in excessive tool wear. The copper element does mean that
drag during machining is reduced making this alloy easier to
machine than LM 6 or 20. Castings made from LM are not suitable
for welding or brazing.
The composition of this alloy is typical of that used throughout
Europe and the United States of America.