HEAT TREATMENT

Jai Enterprises is the Leading Designer of Aluminium Alloys in Coimbatore

HEAT TREATMENT OF ALUMINIUM ALLOYS

Most aluminium castings are used in the ‘as cast’ condition, but there are certain applications that require higher mechanical properties or different properties from the as-cast material. 

The heat treatment of aluminium castings is carried out to change the properties of the as-cast alloys by subjecting the casting to a thermal cycle or series of thermal cycles.  For sand castings and gravity die castings all heat treatments are possible, though not all are standardised.  Pressure die castings however, cannot generally be heat treated.

The following are the suffixes used to indicate the heat treatment condition of BS1490 Aluminium Alloys:

M         As cast
TS       Thermally stress relieved, annealed
TB      Solution heat treated and naturally aged to a substantially stable condition
TB7    Solution heat treated and stabilised
TE       Artificially aged
TF       Solution heat treated and artificially aged
TF7     Solution heat treated, artificially aged and stabilised
The following alloys are not fully heat-treated: LM0, LM2, LM5, LM6, LM20, & LM24.

The following alloys may be heat treated, but their properties are not standardised in the heat-treated condition has shown: LM12, LM21, LM27-TF & LM30-TF.

The following alloys are standardised in the heat-treated conditions indicated: LM4-TF, LM9-TE, LM9-TF, LM13-TE, LM 13-TF, LM13- TF7, LM16-TB, LM16-TF, LM22-TB, LM25-TE, LM25-TB7, LM25-TF, LM26-TE, LM28-TE, LM28-TF, LM29-TE, LM29-TF, LM30-TS.

LM31 is a naturally ageing material, which may also be artificially aged.

DESIGN ADVICE

♦ THE CHOICE OF PROCESS
♦ THE CHOICE OF ALLOY
♦ MACHINING CONSIDERATIONS
♦ HEAT TREATMENT
♦ THE CHOICE OF FINISH