Positron Annihilation Study of Defects Induced by Various Cutting Methods in Stainless Steel Grade 304

Abstract

We report in this article the comparison of the subsurface zones (SZs) in austenitic stainless steel 304 samples created by three cutting techniques, i.e., the laser cutting (LC), abrasive water jet (AWJ), and traditional milling cutting (MC). The crystal lattice defects distribution in this zone were investigated using the positron annihilation method. It was shown that the MC creates the great number mainly edge dislocations decorated by vacancies. Their concentration decreases with the increase of the depth from the cut surface. The total depth of the SZ is extended up to 150 lm from the cut surface. Similar dependency was observed for the AWJ machining but the total depth is much lower, i.e., 40 lm. The laser cut machining generates the zone with the lowest concentration of defects which does not vary with the depth. However, LC affects the sample up to the depth of about 500 lm. The degree of the surface roughness is similar for laser cut and AWJ, but for the MC it is five times smaller.

Positron Annihilation and Complementary Studies of Stainless Steel Exposed to Sandblasting at Different Angles

“…The value for the RF sample is equal to 106 ± 1 ps; similar value can be found in the literature as a bulk value in iron [4]. The component related to the sandblasted sample can be regarded as mean positron lifetime.…”

“…Also the exponential distribution was observed in sandblasted Mg [26]. In case of cutting, a clear character of the decay function was hard to evaluate [4]. In Fig.…”

“…Open-volume defects such as vacancies and their clusters are relatively simple to be observed using positron annihilation spectroscopy (PAS) [3]. Our previous studies have shown successful application of PAS in SZ's studies [4].…”

The Positron Probe Microanalyser Studies of Defect Distribution Induced by Machining of Copper, Iron and Titanium

“…The positron annihilation studies performed by Horodek et al [11] indicated that concentration of defects generated by milling decreased with the increase in the depth from the machined surface. Figure 3 presents similar dependencies of the S-parameter on the depth beneath the machined surface for three well-annealed foils of Cu, Ti and Fe and for four different cutting speeds obtained using the PPMA.…”

“…Surface damage created by diamond saw cutting was studied for single crystal wafers of Cd 1-x Zn x Te [9] and GaAs [10]. Horodek et al [11] applied positron annihilation methods to compare the defect profiles beneath the surface of austenitic steel AISI 304 machined using different techniques, i.e., abrasive water jet cutting, laser cutting and milling. The obtained defect profiles differed essentially from each other.…”