The mechanics of machining selective laser melted super duplex stainless steels

Abstract

Duplex stainless steels come under the difficult-to-machine category, considering the loss of the sensitive balance between the constituent phases due to thermal and mechanical working effects. Selective laser melting is emerging as an additive process for achieving near-net shape manufacturing solutions with these steels. Nevertheless, post-printing machining is essential to varying degrees and the machinability responses of the laser melted duplex stainless steels need sufficient attention. This paper addresses this gap, considering the experimental evaluation of the mechanics of machining with laser melted duplex stainless steels. Specimens printed with the most promising laser melting process conditions are evaluated for machinability, comparing with the wrought counterparts and also ascertaining the differential responses between the as-built and solution annealed states. Cutting forces and thermal measurements confirm better machinability with the laser melted samples which is an interesting finding considering the possibility of laser melting, machining, and post-process heat treatment as the best possible sequence of processing duplex stainless steels to circumvent the difficulties in machining.