The Effect of Quench Aging and Cyclic-Strain Aging on Low Carbon Steel

The present paper is an extension of a previous investigation, and considers the effects of various quench aging treatments on SAE 1010 and 1111 subjected to cyclic strain at aging temperatures. For both of these steels prior quench aging leads to much greater cyclic strain hardening at 250 deg C than was observed from the annealed condition. The strain aging effect was found to be sensitive to the severity of the quench and to strain rate. Cyclic-strain softening was observed when the temperature was restored to room temperature. Of considerable interest is the effect of these general cyclic-aging treatments on subsequent mechanical properties. The fracture ductility of annealed and quenched aged, cyclic-strain aged SAE 1111 was investigated as a function of temperature for uniaxial tension. It was found that the temperature for low ductility, cleavage-type fracture varied considerably depending on the pretreatment. In particular, quench aging and cyclic straining at 250 deg C raised this temperature to slightly below room temperature. The significance of these observations to the behavior of welded joints is discussed. The response of these metals to low-cycle fatigue is also examined.