Effects of vacuum heating in AISI 410 and AISI 321 stainless steels' surface layer revealed by SIMS/GDMS depth profile analysis

Vacuum annealing of steels is employed for out-gassing elements, surface activation and in different production purposes. Such procedure was applied for chromium-nickel AISI 321 and chromium AISI 410 stainless steels used in aviation technologies. Depth profile analysis of the samples annealed in vacuum for 120 min. in 750 and 950 degrees C was performed by using two methods: SIMS and glow discharge mass spectrometry (GDMS). SIMS data were obtained with a 5 keV Ar+ ion gun. In GDMS analyzer, d.c. glow discharge was induced by 1.5 kV d.c. voltage in 1 mbar Ar pressure. Analyses of AISI 321 samples annealed in 750 degrees C show enrichment of titanium, chromium and manganese in the depth range of 150 nm, and depletion in iron and nickel within this range. The sample treated in 950 degrees C shows mainly Ti enrichment into 300 nm depth. Vacuum heating of AISI 410 steel sample in 750 degrees C causes formation of 150-nm-thick surface layer enriched in Cr and Mn and depleted in Fe. In turn, 950 degrees C treatment results in only some increasing of Mn and Ni concentration within 70 nm distance from the surface. The results obtained by SIMS and GDMS confirm each other. However, higher depth profile resolution was obtained by GDMS due to the lower sputtering energy (1.5 kV glow discharge) and due to the use of multidirectional ion bombardment instead of unidirectional bombardment by ion beam in the SIMS method. Copyright (C) 2010 John Wiley & Sons, Ltd.