Usinagem
- USI 98 |
Title
: |
Ruling and indentation
tests used for the investigation of the brittle/ductile transition in
brittle materials |
Abstract
: |
The ability to machine brittle materials in a controlled manner is
required to significantly improve productivity and also to reduce the
sub-surface damage thus eliminating the need for lapping and polishing. Much
effort has been made by
researchers to investigate the feasibility of turning/grinding brittle
materials and to identify criteria for ductile mode machining. For brittle
materials of interest, cutting depths are generally in the sub-micron range.
This requirement, among with others, is well beyond the capability of
conventional turning/grinding machines and the research on brittle materials
is limited to polishing, indentation and scratching when super-rigid
machines are not available. Indentation and ruling tests were used to
investigate the effects of elasto/plastic deformation in the micrometre
scale. Material properties which affect the ductile/brittle behaviour have
been identified and characterised. Brittle materials have been quasi-static
indented and ruled with a range of tool conditions and speeds.
A ductile/brittle transition
was observed when these materials were ruled. The role of material removal
mechanisms such as plastic flow, cutting, delamitation and brittle fracture
were observed. In this study delamitation and plastic flow were obtained
more favourable with tools with large negative rake angles and cutting.
Plastic flow and delamitation however can provide lower material removal
rates and worse dimensional control when compared with cutting mechanisms.
|
Autores
: |
Beltrão, Paulo André de Camargo
Corbett, John
|
Trabalho
Completo : |
|
1o.
Cobef | Comissão Organizadora |
Palestras | Sessões Técnicas |
Autor | Revisores |
|