Surface integrity of bored super duplex stainless steel SAF 2507

Abstract

This investigation explores the effect of some input cutting variables of boring process—cutting speed, feed rate, tool nose radius and coolant pressure—on the surface integrity of super duplex stainless steel grade SAF 2507. The surface integrity was evaluated by means of 3D surface roughness, residual stresses determined by X-ray diffraction, and work hardening using Vickers hardness. The most significant variable was the feed rate, which affected both the roughness parameters and the residual stresses. For the low level of feed rate and the higher nose radius tested the machined surfaces could be identified as Gaussian in terms of surface heights distribution with an insignificant work hardening due to the machining. In this fashion, a best combination of boring conditions could be indicated to reach the lowest roughness values with Gaussian surfaces and compressive residual stresses with a low level of work hardening.