Issue 13

A. Finelli et alii, Frattura ed Integrità Strutturale, 13 (2010) 24-30; DOI: 10.3221/IGF-ESIS.13.03 25 I NVESTIGATED MATERIALS nvestigated steel are largely used in petrochemical industry (e.g., pipes manufacturing). The first investigated steel is a duplex stainless steel (chemical composition in Tab 1) . This tubular shaped material, sized 115x9 mm, has been subjected to the following processing cycle: - Hot extrusion. - Water cooling. - Annealing at 1050° C. - Water cooling. In order to obtain the final pipe dimensions (88.9x6.5 mm), a cold rolling treatment was performed. Mat. C Mn Si S P Ni Cr Mo Cu V Al N A1 0.038 1.37 0.40 0.001 0.013 5.54 21.93 3.00 0.035 0.040 0.045 0.140 A1L 0.038 1.37 0.40 0 .001 0.013 5.54 21. 93 3.00 0.035 0.040 0.045 0.140 5 0.018 1.81 1.01 0.002 0.017 32.60 26.47 3.55 1.01 - - 0.098 4L 0.021 1.28 0.47 0.003 0.018 31.15 26.80 3.34 1.28 0.086 0.047 0.058 Table 1 : Investigated steels chemical compositions. Fig 1 and 2 show duplex stainless steel microstructure, considering longitudinal, transversal and radial sections, respectively before and after the cold rolling treatment (respectively named as “A1” and “A1L”). Figure 1a : “A1” steel microstructure - Longitudinal section (x 200) Figure 1b : “A1” steel microstructure – Transversal section (x 200) Figure 1c : “A1” steel microstructure – Radial section (x 200) Figure 2a : “A1L” steel microstructure - Longitudinal section (x 200). Figure 2b : “A1L” steel microstructure - Transversal section (x 200). Figure 2c : “A1L” steel microstructure – Radial section (x 200). The second investigated steel is a super-austenitic stainless steel (chemical composition in Tab 1) . This tubular-shaped material, sized 121x8.25 mm, has been subjected to the following processing cycle: - Hot extrusion. - Water cooling. A stainless steel with a similar chemical composition was also investigated after a cold rolling treatment, obtaining a tubular-shaped material sized 88.9x6.5 mm). I