Last modified: 2014-11-25
Abstract
Designers of austenitic stainless steel parts do not always specify in detail in what state the work material should be delivered, e.g. annealed or annealed with subsequent cold forming. When a final cold forming step is added there will be an increase in hardness and strength while ductility at the same time is reduced. The mechanical properties of austenitic steels can thus vary significantly and cause unplesant surprises in the machining processes if the delivery state is not clearly specified. The aim of his study is to investigate delivery state effects on two selected machinability criteria; cutting forces and chip breakability. Two different insert grades with the same chip breaker geometry are used, one with a thin physical vapor deposition (PVD) coating and the other one with a thicker chemical vapor deposition (CVD) coating. Both the annealed and the cold drawn delivery states are investigated, and it is shown that cold drawn material gives lower cutting forces for both tool types as well as better chip breakability when combined with the PVD coated tool.