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Shaft Design
Published in Wei Tong, Mechanical Design and Manufacturing of Electric Motors, 2022
Either cold-rolled or hot-rolled carbon steel can be used for making motor shafts. Hot-rolled steel is produced at temperatures above the recrystallization temperature of steel. In contrast, cold-rolled steel is produced under the recrystallization temperature of steel (more regularly, at room temperature). The benefits of cold-rolled steel over hot-rolled steel are as follows: (a) The strength of cold-rolled steel can increase by 15%–30% due to the strain-hardening mechanism. (b) Cold-rolled steel has a smooth surface finish compared to hot-rolled steel. (c) Cold-rolled steel products have tight dimensional tolerances. However, the cold rolling process can generate residual stresses remaining in the rolled steel. Furthermore, the cost of the cold rolling process is usually higher than that of hot rolling.
Effects of HAZ softening on the strength and elongation of resistance spot-welded joints in high-strength steel sheet in an in-plane tensile test
Published in Welding International, 2018
Fujimoto Hiroki, Hamada Kouichi, Okada Toru, Fujii Hidetoshi
There has been increased use of high-strength steel sheet in motor vehicle bodies to achieve both improvements in motor vehicle impact safety and improvements in fuel consumption due to reduction in body weight. Examples of the use of cold-rolled steel sheet with a tensile strength of 1180 MPa have been reported [1], and steel sheet with a tensile strength of 1500 MPa after quenching has been manufactured by the hot stamping method (also known as the hot press method and die-quenching method), in which the steel sheets are heated, hot press formed and simultaneously quenched, and this has found a range of applications. More recently, examples of the use of 1800 MPa hot-stamped steel sheet have been reported [2]. There are many cases in which the tensile strength of this kind of high-strength steel is maintained through the use of martensitic transformation, but when spot welding is carried out, a phenomenon occurs in which the heat-affected zone (HAZ) becomes softer than the base metal due to tempering [3–5]. There have been reports that, in automotive steel sheet, HAZ softening has been observed in spot welds from the point at which the tensile strength exceeds 780 MPa [5].
Life Cycle and Cost Assessment of a Marine Scrubber Installation
Published in Journal of International Maritime Safety, Environmental Affairs, and Shipping, 2020
Klara Andersson, Byongug Jeong, Hayoung Jang
The large amounts of black steel accounted for leads to the notion that auxiliary components such as sludge and holding tanks could be included in the LCA inputs. Since the steel in cold-rolled steel coils are usually too thin to construct ship tanks, it is assumed that steel plates for tank construction needs to be added to the case ship LCA inputs (Nippon Steel Corporation 2020).