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Case Study

Case Study. What die materials and fabricated structures could be investigated to allow for semi-solid steel forming? . Ceramic die materials. Characteristics required Mechanical – Strength, Wear, Fatigue Thermal shock Thermal fatigue Corrosion Oxidation.

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Case Study

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  1. Case Study • What die materials and fabricated structures could be investigated to allow for semi-solid steel forming?

  2. Ceramic die materials Characteristics required • Mechanical – Strength, Wear, Fatigue • Thermal shock • Thermal fatigue • Corrosion • Oxidation • 1. She, J., and Ohji, T., Thermal shock behavior of porous silicon carbide ceramics, J. Am. Ceram. Soc., 85, 8, 2002 • 2. Meyer-Rau, S. and Telle, R., Testing strategies for corrosive interaction of ceramics with semi-solid and molten metal alloys, J. of European Ceramic Society, 25, 2005 • 3. Evans, H., and Taylor, M., Oxidation of high temperature coatings, J. Aerospace Engineering, IMechE, 220, Part G, 2006 • 4. Velay, V., et al., A continuum damage model applied to high temperature fatigue lifetime prediction of a martensitic tool steel, Fatigue Fract Engng Struct, 28, 2005.

  3. Ceramic die materials • Partially stabilised zirconia – US4279655 (’81) and by Mg, Ca or Y additions CA1053709 (’79) • Cermet casting mould – FR1258926 (Renault) • alumina in Fe, Cr, Al mix; pressed between 7000 and 70,000 psi and sintered between 2190 and 2640 deg F; TBC / lubricants applied: alumina, silica, silico-aluminate, graphite, lamp or acetylene black

  4. Metal die materials • H13 tool steel • reduce heat checking by substituting with material with higher elevated mechanical properties • reduce magnitude of thermal stress, for example, by increasing the bulk metal die temperature • Ni based super alloys • e.g. INCONEL, Cr-Ni-Mo • Electroslag cast steel • good ductility and toughness as well as high tensile strength at elevated temperatures - important for high thermal shock resistance • Sakhuja, A., and Brevick, J., Prediction of thermal fatigue life in tooling for die-casting copper via finite element analysis, Am. Inst. Phys., 2005. • Fang, J., et al., The characteristics of fatigue under isothermal and thermo-mechanical load in Cr-Ni-Mo cast hot die steel, Fatigue FractEngngStruct, 25, 2005. • 3. Moon, Y., Kim, J., and Tyne, C., Thermal shock resistance of electroslag cast steel for hot working tools, J. Mat. Proc. Tech., 115-156, 2004.

  5. Die fabtrication methods • Machining from bulk feedstock – conventional • Sintering – metal and ceramic feedstock • Cladding by shrink fitting – GKN Patent US3664411 (’73) • Multiple layer ceramic – similar to LOM principle – EP1042803 (2000) • glass & alumina powder sintered into 0.2 mm thick sheets; applicable to metal carbides: B4C, SiC, & TiC and metal nitrates: Si3N4, BN, & TiN • Sialon ceramic with metal coating – JP1011046 (’89) •  and  sialon with metal compound coating film e.g. super hardened Ti, Si, … film, by ion planting • Clamped ceramic columns of polygon cross section – JP63171239 (’88) • applicable with metal oxide or metal nitride (e.g. Si3N4 and ZrO2) • Mould insert used as cladding – WO2006004713 (’06) • from developer of melt away core process

  6. Fabricated die structure • Bulk metal • Bulk ceramic • Cermet • Layered structure / Hybrid structure • Channels for heating/cooling cartridges / heat transfer fluid • Inserts / shapes that reduce heat build up

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