The microstructure and mechanical properties of austenitic stainless steel 316 LVM (Low Vacuum Melting) blasted with either small and rounded ZrO2 particles or larger and angular shaped Al2O3 particles are analysed through magnetic force microscopy, synchrotron radiation diffraction and ultramicroindentation techniques. It is shown that blasting causes a severe plastic deformation that roughens the surface and produces a significant subsurface grain refinement and work hardening. The gradient in the plastic deformation and the volume increase associated with the deformation induced α′-martensite account for the development of compressive residual stresses with a maximum value close to the surface. All these features yield a gradient in hardness with a maximum value beneath the surface. Compared with the Al2O3 particles, the ZrO2 particles cause a higher value of compressive residual stress and a lower increase in hardness. Also, the Al2O3 particles lead to more α′-martensite formation at deeper regions from the surface than the ZrO2 particles. The different results are related with the specific morphology of the particles and their specific role in the blasting process.

The authors wish to express their thanks for the financial support of the Spanish Projects MAT2006-12948-C04-01, MAT2009-14695-C04- 02-04 and the CIBER-BBN of Bioingeniería, Biomateriales y Nanomedicina, supported by the ISCIII. Dra M.M. thanks grants of “Juan de la Cierva” (MICINN) and JAE-DOC (CSIC). The authors thank J.A. Jiménez for the X-ray measurements help and the ICMM-SPM Service for the AFM/MFMmeasurements. Support fromBESSY for the SRDexperiments on EDDI under proposal nº 2008-2-80215 and help fromM. Klaus is also gratefully acknowledge.

Peer reviewed