FRACTURE SURFACES OF HIGH Mn STEEL AFTER CHARPY IMPACT TEST
Depending on the ability of material to undergo plastic deformation before the fracture two fracture modes can be defined - ductile or brittle.
• Ductile fracture - most metals
Extensive plastic deformation ahead of crack
Crack is “stable”: resists further extension unless applied stress is increased
· Brittle fracture - ceramics, ice, cold metals:
Relatively little plastic deformation
Crack is “unstable”: propagates rapidly without increase in applied stress
This is fracture surface of high Mn steel sample after rolling which shows a combined brittle and ductile fracture. The features are many ductile dimples ,voids indicating the ductile failure, and cleavage planes (flat planes with small atomic steps indicating brittle fracture.
This is a fracture surface of solution annealed high Mn steel sample shows a complete ductile fracture having small and uniform dimples.