CONSTANT-AMPLITUDE FATIGUE BEHAVIOR OF FIVE CARBON OR LOW-ALLOY CAST STEELS AT ROOM TEMPERATURE AND minus 45 degree C.

Five common carbon or low-alloy cast steels - SAE 0030, SAE 0050A, C-Mn, Mn-Mo and AISI 8630 - were subjected to constant-amplitude fatigue tests at room temperature and at the common low climatic temperature of minus 45 degree C ( minus 50 degree F). Tests included smooth specimen axial low and high cycle fatigue and compact type (CT) specimen crack growth behavior from 10** minus **5 m/cycle (4 multiplied by 10** minus **4 in. /cycle) to threshold values at 10** minus **1**0 m/cycle (4 multiplied by 10** minus **9 in. /cycle). All five cast steels showed equivalent or better fatigue resistance at the low temperature, except for some very short life low-cycle fatigue tests and for some very high fatigue crack growth rates where fracture was imminent. Scanning electron fractographic analysis indicated that ductile type fatigue crack growth mechanisms occurred for all steels at both test temperatures