Casting material for thixocasting, method for preparing partially solidified casting material for thixocasting, thixo-casting method, iron-base cast, and method for heat-treating iron-base cast
AssigneeHonda Giken Kogyo Kabushiki Kaisha
InventorsTakeshi Sugawara, Haruo Shiina, Masayuki Tsuchiya, Kazuo Kikawa, Isamu Takagi
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Abstract
A thixocast casting material is formed of an Fe--C--Si based alloy in which an angle endothermic section due to the melting of a eutectic crystal exists in a latent heat distribution curve and has a eutectic crystal amount Ec in a range of 10% by weight <Ec<50% by weight. This composition comprises 1.8% by weight .ltoreq.C.ltoreq.2.5% by weight of carbon, 1.4% by weight .ltoreq.Si.ltoreq.3% by weight of silicon and a balance of Fe including inevitable impurities.
Claims10
A thixocast casting material which is formed of an Fe--C--Si based alloy in which an angled endothermic section due to the melting of a eutectic crystal exists in a latent heat distribution curve, and a eutectic crystal amount Ec is in a range of 10% by weight .ltoreq.Ec.ltoreq.50% by weight.
A process for preparing a thixocast semi-molten casting material, comprising the steps of selecting a casting material in which a difference g-h between maximum and minimum solid-solution amounts g and h of an alloy component solubilized to a base metal component is in a range of g-h.gtoreq.3.6 atom %, said casting material having dendrite phases comprised of the base metal component as a main component;
- and heating the casting material into a semi-molten state with solid and liquid phases coexisting therein, wherein a heating rate Rh (.degree. C./min) of said casting material between a temperature providing said minimum solid-solution amount h and a temperature providing said maximum solid-solution amount g is set in a range of Rh.gtoreq.63-0.8D+0.013D.sup.2, when a mean secondary dendrite arm spacing of the dendrite phases is D (.mu.m).
An Fe-based cast product, which is produced using an Fe--C--Si based alloy as a casting material by utilizing a thixocasting process, followed by a finely spheroidizing thermal treatment of carbide, wherein an area rate A.sub.1 of graphite phases existing in a metal texture of said cast product is set in a range of A.sub.1 <5%.
A thixocasting process comprising a first step of filling a semi-molten casting material of an Fe--C--Si based alloy having a eutectic crystal amount Ec lower than 50% by weight into a casting mold;
- a second step of solidifying said casting material to provide an Fe-based cast product;
- a third step of cooling said Fe-based cast product, a mean solidifying rate Rs of said casting material at said second step being set in a range of Rs.gtoreq.500.degree. C./min, and a mean cooling rate Rc for cooling to a temperature range on completion of the eutectoid transformation of said Fe-based cast product at said third step being set in a range of Rc.gtoreq.900.degree. C./min.
Dependencies are inferred from the claim text.