Identification of Thermal and Microstructural Properties of Hot Rolling Scale

Abstract

<p class="AMSmaintext2">A significant amount of scale is produced during casting of ingots and processing of hot-rolled products. In manufacturing steel, during the various rolling operations, the amount of scale produced is approximately 0.1% of the annual production of the rolling mills. The quality of the thin sheet during rolling is affected by the behavior of the iron oxide layers formed on their surfaces. For this reason, acids and oils are used for the descaling of slabs and billets by means of pressurized water. The calamine, contaminated by these various acids and used oils, is rejected and stored involuntarily on important areas and pollutes soil and groundwater. Micrographic observations as well as X-ray diffraction analysis have shown that calamine consists mainly of iron oxides. Hematite and magnetite become the main components for oxidation times greater than 1 hour. Characterization tests have shown that calamine is dense (ρ = 4.8 g/cm<sup>3</sup>), its particle size is variable depending on the degree of oxidation (from 0.5 to 10 mm). Simultaneous thermal analysis showed that an increase in mass of the calamine sample with a release of heat. Studies are underway for the physico-chemical characterization of the soils of the storage areas.</p>

Case Study of the Tensile Fracture Investigation of Additive Manufactured Austenitic Stainless Steels Treated at Cryogenic Conditions

“…AM shows the potential to substitute conventional metal manufacturing processes, such as casting and forging [3,4], mainly in the aerospace and biomedical fields. Thanks to improved reliability and reproducibility of the processes, AM competes with other progressive processes such as severe plastic deformation (SPD) [3][4][5][6][7] with substantial advantages such as the absence of constraints in the manufacturing design, shape freedom, high complexity of the components, combination of multiple parts into one part, production of functionally graded materials, reduced tooling requirements, and the possibility of production on demand [8][9][10].…”

“…The laser powder bed fusion process (LPBF), also known as selective laser melting (SLM), directly produces homogenous metal objects, layer by layer, from 3D Computer Assisted Drawing (CAD) data, by selectively melting fine layers of metal powder with a laser beam [1][2][3][4][5][6][7][8]. A considerable amount of material can be saved by designing properly for additive manufacturing with no loss in terms of mechanical properties [11][12][13].…”

“…Especially, in AM products, cryogenic treatment is still very rare. The austenitic 316L grade is a popular steel for cryogenics as demonstrated by the vast literature, with special applications in the field of liquid gas confinement and storage [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. Mechanisms governing tensile properties at cryogenic temperatures for wrought materials have been extensively and deeply investigated [ 25 ].…”