Papers by Keyword: Levitation Melting

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Authors: Noriki Fujita, Takayuki Narushima, Yasutaka Iguchi, Chiaki Ouchi
Authors: S. Hotta, Taichi Murakami, Takayuki Narushima, Yasutaka Iguchi, Chiaki Ouchi
Abstract: Currently new continuous casting processes such as thin slab caster or strip casting are industrialized or under developing in the world steel makers. In these casting processes, cooling rate after solidification becomes much faster compared with thick slab caster, and hot rolling mill connected directly with casting machine tends to be installed. The present study was conducted to investigate variations of austenitic grain size and micro segregation with cooling rate after solidification and also direct hot deformation conditions in austenite immediately after solidification in HSLA steels. HSLA steels were 0.15%C-0.25%Si-1.50%Mn, 0.028%Nb and 0.028%Nb-0.015%Ti with the same basic compositions. A hot working simulator of THERMECMASTER-Z was used, and the center part of tensile specimen set up in this machine was partially or fully levitation-melted by induction heating under argon gas atmosphere. After melting, specimens were cooled at cooling rate from 0.4K/s to 40K/s, and this range covered cooling rates after solidification in heavy thick slab caster and strip casting. Direct hot tensile straining in austenite after solidification was conducted at strain rates from 1.4×10-3s-1 to 2.6s-1, corresponding to an extracting speed in a respective caster. The increase of cooling rate refined continuously as cast austenitic grain size, and it was enhanced in micro alloyed steels. Micro segregation such as Mn was improved by faster cooling. Direct straining after solidification markedly refined austenitic grain size through dynamic or static recrystallization occurring depending on strain rate.
Authors: Sergejs Spitans, Egbert Baake, Andris Jakovics
Abstract: In this paper a new drip-and leakage-free method for the electromagnetic levitation melting of metallic samples with greater weights, stabilized position and free surface shape is presented. The method can be used in a melting furnace, as well as for the coreless induction valves applied for the flow rate control, e.g. in the continuous casting of molten metals.The applicability of the method was examined numerically and experimentally proved by tests conducted with different types of laboratory setups.
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