Surface composition and near-surface hardness studies on high dose boron-implanted 304 stainless steel

Abstract

The modification of boron-implanted near surface of 304 stainless steel having strained and strain-free surfaces was studied. The energy of the boron ion was 130 keV at a dose of 2.5 x 1017 ions cm-z. Ion-implantation is known to modify the tribological properties of metals, however, it is not well-understood as to how such a shallow implanted layer can affect the microhardening. A full understanding of the process involved is yet to emerge. In the present work the ion implanted layer was characterized for boron depth profiles using AES and XPS. The implanted layer is observed to contain B/t3, Fe2B, FeB and CrBz compounds with small fractions of chromium and iron oxides. The strain-free surface of 304 SS shows an increase in microhardness by ~ 8070 after boron ion implantation at 2 gf and the strained surface by ~ 30~ at the same load. The annealing effects on microhardness for mechanically polished and implanted samples were also investigated in the temperature range 100 to 400°C. The possible correlation of near-surface microhardness increase with boride formation is discussed.

Laser Boronizing of Additively Manufactured 18Ni-300 Maraging Steel Part Surface

“…When the laser speed was increased to 750 mm/min, and the boron concentration to ~4.1 wt.%, the intensity ratio of these two peaks changed in favor of the peak at a higher BE that corresponds to borides. With a further increase in laser speed and boron concentration, the peak at ~187 eV disappeared and only a single peak at ~188 eV was observed, which in works dealing with steel processing is associated mainly with Fe 2 B borides [41,42]. The B1s peaks between ~191 eV and ~194 eV are mainly associated with boron oxides [39,40,42,43].…”

“…With a further increase in laser speed and boron concentration, the peak at ~187 eV disappeared and only a single peak at ~188 eV was observed, which in works dealing with steel processing is associated mainly with Fe 2 B borides [41,42]. The B1s peaks between ~191 eV and ~194 eV are mainly associated with boron oxides [39,40,42,43]. In [43], a broad B1s peak between ~190 eV and ~194 eV was considered to be due to the formation of non-stoichiometric oxides; three equally spaced subpeaks were attributed to B-O (lowest BE), O-B-O and B 2 O 3 (highest BE).…”