โ Scribed by T.C Lindley
No coin nor oath required. For personal study only.
Low temperature tensile tests have been used to evaluate the effect of pre-strain and strain-ageing 0x1 the brittle fracture characteristics of a high manganese steel.
In contrast to the behaviour of iron and low-manganese steels, a pre-strain at 20ยฐC does not reduce the elongation to fracture on immediately retesting in the ductile cleavage temperature region. A strong strain-ageing treatment causes a marked reduction in elongation to fracture at -196"C, while a re-strain at 29ยฐC of fully strain-aged materiel restores the ductility rtt -196ยฐC. The pre-strain and ageing experiments indicate that the presence of locked dislocations, the occurrence of mechanical twinning and the increased applied stress level due to strain-ageing, all play a role in the strain-ageing embrittlement of the m&e&l.
Me~llo~r&pbic observations on deformed and fractured test-pieces suggest that the critical event for complete fracture is the formation of a single-grain microcrack rather than its subsequent propagation through grain boundaries.
๐ SIMILAR VOLUMES
A study has been made of the effect of dynamic strain-ageing on the initiation and propagation of ductile fracture in mild steel. Grain boundary carbide cracking has been found to contribute to void formation in the tempereture range 77ยฐK to 573ยฐK. Using scenning electron microscopy it hes been show