fe ni si cu mg______________________________________505318 79 2 2 6 15 7 1 2 1 0 2505319 79 7 2 9 15 2 1 3 8 0______________________________________ fig2 and 3 are for castings in the t5 temper 8 hours at 450 u00b0 f holding the alloy at elevated temperature e g 1000 hours at 700 u00b0 f operates to make the microstructure less acicular as compared to fig2 and 3 table i lists the mechanical properties of the alloys at room temperature and at temperature after 1000 hours exposure to such temperature fig1 shows the yield strength as a function of temperature these data indicated that the trend for high temperature stability continues up to 700 u00b0 f yield strengths between 8 and 10 ksi were achieved with mg containing alloy still maintaining an approximate 2 ksi advantage over the mg free alloy for comparison wrought alloy 2219 long recognized as a superior elevated temperature alloy displays a yield strength of 3 5 ksi at 700 u00b0 f also casting alloys 242 332 and 336 the most commonly used elevated temperature casting alloys all have yield strengths of about 3 5 ksi at 700 u00b0 f table i__________________________________________________________________________mechanical properties of experimental casting alloys room temperature 1000 hrs at 500 u00b0 f 1000 hrs at 600 u00b0 f 1000 hrs at 650 u00b0 f 1000 hrs at 700 u00b0 f t s y s t s y s t s y s t s y s t s y s ksi ksi el ksi ksi el ksi ksi el ksi ksi el ksi ksi __________________________________________________________________________ el.