Authors:
Markus Schneider (1), Dennis Wawoczny (1), Kevin Haffke (1)
1- GKN Powder Metallurgy Engineering GmbH, Radevormwald, Germany
Abstract:
The critical grain depth of cut hcu, crit. is a grinding metric which controls the transition from a ductile grinding regime to a brittle grinding regime and it can be correlated with several material parameters. A ductile grinding regime is preferred because it does not damage the bulk material. Intermetallic compounds, e.g. sintered Nd2Fe14B hard magnets, are very brittle and therefore prone for chipping defects. The fracture toughness KIc is a relevant factor – with a quadratic effect – in the equation of the critical grain depth of cut hcu, crit. and controls the required grinding process parameters. Anyhow, the conventional plane-strain fracture toughness derivation method with chevron notched 3-point bending specimens is very expensive due to the needed electro discharge machining (EDM) procedure to wire erode the chevron-shaped notch. As an alternative the indentation based Palmqvist toughness method was applied with good results. The derived fracture toughness KIc values are very low but in a reasonable range.
DOI:
https://doi.org/10.59499/EP246319981
