Hot tearing in the AA1050 alloy was investigated in real time and in situ using acoustic emission (AE) and cooling curve analysis techniques and a ring mold. Activities involving AE have been detected in three zones of the solidification curve. The characteristic signals for hot tearing were an AE energy of over 600 e.u. and an average frequency of approx125 + - 15 kHz in zone II. For hot cracking, the AE energy was over 650 e.u. and the average frequency was -128 + - 17 kHz in zone III. The hot-tear start temperature ranged from 636 deg C to 653 deg C; the nonequilibrium solidus T_s, from 556 deg C to 614 deg C; the fraction solid at hot-tear onset from 0.71 to 0.99; and the Clyne-Davis hot-tear susceptibility coefficient (HSC) from 0.25 to 0.81. The HSC correlated inversely with a total energy of solidification cracking (E_(total)) HSC approx 167(E_(total))~(-0.8). A hot-tear susceptibility factor (HSF) = (pct Fe) centre dot (cooling rate (CR))~2 was related to the HSC and T_s as HSC = 0.002 HSF + 0.3 and T_s = -0.3 HSF + 617.
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