Stress Distribution and Crack Formation on Sliding Gate

Transcription

1 Future Work 011 UIUC, August 1, 010 Stress Distribution and Crack Formation on Sliding Gate Hyoung-Jun Lee, Seong-Mook Cho, Seon-Hyo Kim Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang, Kyungbuk , South Korea Brian G. Thomas Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 106 W.Green St., Urbana, IL, USA, Sang-Woo Han, Tae-In Jung, Joo Choi POSCO Technical Research Laboratories, POSCO, Pohang, Kyungbuk , South Korea University of Illinois at Urbana-Champaign Pohang University of Science and Technology Metals Processing Materials Simulation Science Lab and Engineering Lance Hyoung-jun C. Hibbeler Lee 1 1

2 Patterns of Cracks Formed on Sliding Gate Refractory Service life of sliding gate plate acts as a limiting factor to achieve the expected SEN performance on continuous caster Sliding gate refractory Steel bend Longitudinal cracks [Schematic of casting equipment] New Generation Ladle Slide Gate System for Performance Improvement, J. Chaudhuri, 007 Outside cracks Types of crack Outside cracks Longitudinal cracks Transversal cracks Transversal cracks Caused by Thermal expansion Thermal expansion Plate support load [Rectangular-rounded plate with cracks] [Schematic of sliding gate plate] Steel and Refractory Chemical Interactions and Mechanical Behavior of Plates for Sliding Gate during Steel Continuous Casting, V. Munteanu, 008 Pohang University of Science and Technology Materials Science and Engineering Hyoung-jun Lee

3 Why Cracks are Formed in Sliding Gate Thermal stress induced by temperature distribution of sliding plate with pre-heating and molten steel temperature High surface pressure from cassette supporting 3 sliding gate plates Ferro-static pressure due to height difference between tundish free surface and sliding gate location Friction force caused by mechanical movements for stabilizing the mold meniscus level Pohang University of Science and Technology Materials Science and Engineering Hyoung-jun Lee 3

4 Components of Sliding Gate upper cassette upper plate middle plate steel bend jig bolt lower plate steel bend lower cassette [Schematic of sliding gate parts drawing by Abaqus] Pohang University of Science and Technology Materials Science and Engineering Hyoung-jun Lee 4

5 Plate Contacting Geometry with Cassette Upper plate Screw Forced clamp Steel bend Fixed clamp on upper cassette Jig Cylinder Middle plate steel bend Screw Fixed clamp on jig Forced clamp Lower plate Screw Forced clamp steel bend Fixed clamp on lower cassette [Schematic of sliding gate plates contacting geometry (top view)] Cylinder is connected to middle plate via jig Each plate enclosed by steel bend is fixed by forced clamp Pohang University of Science and Technology Materials Science and Engineering Hyoung-jun Lee 5

6 Parameters Considered for Computational Modeling Temperature Tundish Tundish Free Surface - Pre-heating temp. : Sliding gate is heated from room temp. to pre-determined temp. steel bend Sliding gate plate Temp. Input h UTN - Molten steel temp. : Pre-heated Molten steel flows through sliding gate hole, during continuous casting Temp. Input Pohang University of Science and Technology Materials Science and Engineering Hyoung-jun Lee 6

7 Parameters Considered for Computational Modeling Load imposed on sliding plate Tundish Cassette is loaded by 3.5 ton weight through 4 screws bolted from bottom to top Tundish Free Surface bolt load 3500 : kg screws m/s N h UTN Ferro-static pressure P h SG P atm Ferro-static Pressure 3 SpecificWeight (kn/m ) h gh P atm Pa h ; Molten Steel Depth (m) kg/m 9.81 m/s 1.8 m 3 ; Density (kg/m ) g ; Gravitational Acceleration (m/s ) kg/m s kg m/s N/m m P SG Pa Pa Pa Pa Pohang University of Science and Technology Materials Science and Engineering Hyoung-jun Lee 7

8 Parameters Considered for Computational Modeling Mechanical movement (Friction force) Cylinder is working back and forth to stabilize the mold meniscus level with velocity of approx m/s Steel bend Jig Cylinder Sliding gate plate Pohang University of Science and Technology Materials Science and Engineering Hyoung-jun Lee 8

9 Future Plan Stress distribution will be investigated considering 5 different parameters on sliding gate plates with different opening ratio Crack Initiation and propagation will be investigated How stresses are affected on plates depending on different pre-heating temperature will be considered Pohang University of Science and Technology Materials Science and Engineering Hyoung-jun Lee 9

10 Acknowledgements Continuous Casting Consortium Members (ABB, Arcelor-Mittal, Baosteel, Corus, LWB Refractories, Nucor Steel, Nippon Steel, Postech, Posco, ANSYS-Fluent) POSCO : Jong-Tae Ahn, Duck-hee Lee POSTECH : Soo-Hyun Joo Pohang University of Science and Technology Materials Science and Engineering Hyoung-jun Lee 10