Inclusions Generated during Ingot Casting of Tool Steel

Ragnarsson, L.-Å.; Sichen, Du

doi:10.1002/srin.200900064

Cited by 19 publications

(18 citation statements)

References 17 publications

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“…[2] In particular, the generation of non-metallic inclusions during casting process through deoxidization in ladle and mold even as interaction between refractory and steel was investigated. [13,21,22] The present paper focusses on the effect of different carbonbonded crucible materials for ingot casting on size and distribution of non-metallic inclusions and their influence on the mechanical behavior of a case-hardening steel 18CrNiMo7-6 (AISI 4317). Thus, the quasi-static, dynamic fracture toughness, and fatigue behavior were investigated.…”

Section: Introductionmentioning

confidence: 99%

Effect of Crucible Material for Ingot Casting on Detrimental Non‐Metallic Inclusions and the Resulting Mechanical Properties of 18CrNiMo7‐6 Steel

et al. 2017

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The steel 18CrNiMo7-6 (AISI 4317) is treated in three different crucibles based on carbon-bonded alumina. Non-metallic inclusions in the steel are characterized by means of optical microscopy and scanning electron microscopy. Strength, ductility, and dynamic fracture toughness of the steel are evaluated at different temperatures. Furthermore, fatigue lifetimes in the very high cycle regime are determined. The treatment in a carbon-bonded alumina (A-C) crucible resulted in a relatively high inclusion content involving a high number of duplex inclusions consisting of MnS and Si-Al-O. In contrast, less but large pure MnS inclusions are observed when the steel is treated in carbon-bonded alumina-zirconia-titania crucibleswith or without a coating of carbon nanotubes (AZT-C-n and AZT-C). The steel treated in the A-C crucible exhibits the highest strength and fatigue lifetime, but the lowest energy dissipation. The relatively low inclusion content in the AZT-C treated steel results in high energy dissipation during tensile deformation. However, large MnS inclusions in the AZT-C and AZT-C-n treated steels act as crack initiation sites and reduce the fatigue lifetime. The dynamic fracture toughness is not affected by the different melt treatments. This result is explained by cell-like structures within the material that are characterized by a lower strength and an increased concentration of MnS inclusions.

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Section: Introductionmentioning

confidence: 99%

Effect of Crucible Material for Ingot Casting on Detrimental Non‐Metallic Inclusions and the Resulting Mechanical Properties of 18CrNiMo7‐6 Steel

et al. 2017

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“…The increased oxygen content would result in undesired reoxidation. In a previous study, 5 reoxidation during ingot casting is evidently observed. Alumina is formed on the surface of casting power forming micro-inclusions in the ingot.…”

Section: Introductionmentioning

confidence: 64%

“…The decreased contents of oxygen and nitrogen in the final products are strong evidence of improvement. 5,6 Despite of argon protection, entrainment of oxygen into the liquid steel is still noticed. The increased oxygen content would result in undesired reoxidation.…”

Section: Introductionmentioning

confidence: 99%

Physical and mathematical modelling of argon shroud for protection of steel stream during casting

Ragnarsson¹,

Song²,

L.³

et al. 2010

International Journal of Cast Metals Research

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Physical modelling of argon shroud was carried out using a two-dimensional 1 : 1 scaled model in order to gain a basic understanding of air entrainment during casting. The flow pattern of protective gas was determined with particle image velocimetry technique. Computational fluid dynamics calculations were also conducted. The results of the particle image velocimetry measurements and computational fluid dynamics modelling showed mutual agreement. The main findings of the present study are the following. First, the use of vertical gas inlet outside the collar on the top of the vertical runner should be avoided. Second, the distance between the ladle and the collar should be minimised to reduce the oxygen entrainment by convection and diffusion. Third, a modest flowrate of argon gas should be used. Further increase in the gas flow does not seem to improve the protection.

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“…This can well explain the fact that only the casting powder in the range of 10-30 mm is found in the ingot. 5 Eriksson et al have carried out CFD calculation for ingot filling. 15 Based on the fact that the surface deformation is almost flat at a filling height and the average surface velocity, the authors suggest 25u as the best inlet angle.…”

Section: Discussionmentioning

confidence: 99%

“…A previous study of the present research group shows that two new types of inclusions are introduced during ingot casting. 5 While the inclusions of the first new type, macro in size, are formed due to reoxidation, the inclusions of second type are generated by entrainment of casting powder. Findings of inclusions originating from the casting powder are also reported by other researchers.…”

Section: Introductionmentioning

confidence: 99%

Flow pattern in ingot during mould filling and its impact on inclusion removal

Ragnarsson

Eliasson

et al. 2010

Ironmaking & Steelmaking

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A two-dimensional non-steady state computational fluid dynamic model was employed to gain a basic understanding of the flow in the ingot during casting. The surface velocity was found to be affected by the inlet angle and was found to vary with the casting level. The information of surface velocity was related to the probability of the inclusion removal. Water model experiments were also conducted to help the understanding. The model calculation revealed the same trends as the results of water model experiments. Both computational fluid dynamic data and the physical modelling showed that the inlet angle of 5u currently used in the industry was a good alternative regarding inclusion removal. The present work suggests strongly that the melting shop should try to obtain a liquid or semiliquid film at as early stage as possible in ingot casting.

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Inclusions Generated during Ingot Casting of Tool Steel

Cited by 19 publications

References 17 publications

Effect of Crucible Material for Ingot Casting on Detrimental Non‐Metallic Inclusions and the Resulting Mechanical Properties of 18CrNiMo7‐6 Steel

Effect of Crucible Material for Ingot Casting on Detrimental Non‐Metallic Inclusions and the Resulting Mechanical Properties of 18CrNiMo7‐6 Steel

Physical and mathematical modelling of argon shroud for protection of steel stream during casting

Flow pattern in ingot during mould filling and its impact on inclusion removal

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