Claims
- 1. A process for producing a thixocast semi-molten casting material comprising the steps of preparing a thixocast material including an outer layer portion having dendrites around an outer periphery of a main body portion, subjecting the thixocast material to a heating treatment to thereby produce a semi-molten casting material having solid and liquid phases coexisting therein, said heating treatment comprising primary and secondary induction heating steps, conducting said primary induction heating step at a frequency f.sub.1 for transforming said dendrites into spherical solid phases by preferentially increasing a temperature of said outer layer portion relative to a temperature of said main body portion thereby to bring said outer layer portion into a semi-molten state, and conducting said secondary heating step at a frequency f.sub.2 lower than said frequency f.sub.1 of the primary induction heating step to raise the temperature of said main body portion and bring said main body portion into a semi-molten state during said secondary induction heating step.
- 2. A process for producing a thixocast semi-molten casting material according to claim 1, wherein an average diameter D of said spherical solid phases in the outer layer portion in said semi-molten state is in a range of D.ltoreq.200 .mu.m.
- 3. A process for producing a thixocast semi-molten casting material according to claim 1 or 2, wherein said casting material comprises an aluminum alloy, and wherein the frequency f.sub.1 of said primary induction heating step is set in a range of 0.8 kHz<f.sub.1 .ltoreq.50 kHz, and the frequency f.sub.2 of said secondary induction heating step is set in a range of 0.8 kHz.ltoreq.f.sub.2 .ltoreq.5 kHz.
- 4. A process for producing a thixocast semi-molten casting material according to claim 3, wherein an area rate of .alpha.-Al crystals in said outer layer portion is represented by a%, an area rate of .alpha.-Al crystals in said main body portion is represented by b%, and a difference a%-b% between the area rates is in a range of 5%.ltoreq.a%-b%.ltoreq.15%.
- 5. A process for producing a thixocast semi-molten casting material of an aluminum alloy, comprising:
- preparing a thixocast material including an outer layer portion having dendrites around an outer periphery of a main body portion with an area rate of .alpha.-Al crystals in said outer layer portion being a%, an area rate of .alpha.-Al crystals in said main body portion being b%, and a difference a%-b% between said area rates being in a range of 5%.ltoreq.a%-b%.ltoreq.15%; and
- subjecting said thixocast material to a heating treatment to produce a semi-molten casting material having solid and liquid phases coexisting therein and transforming said dendrites into spherical solid phases by preferentially increasing a temperature of said outer layer portion relative to a temperature of said main body portion and thereby to bring said outer layer portion into a semi-molten state.
- 6. A process for producing a thixocast semi-molten casting materials according to claim 5, wherein the preferential increasing of the temperature of said outer layer portion is achieved by an induction hearing.
- 7. A process for producing a thixocast semi-molten casting material according to claim 5 or 6, wherein an average diameter D of said spherical solid phases in said outer layer portion in the semi-molten state is in a range of D.ltoreq.200 .mu.m.
Priority Claims (1)
Number |
Date |
Country |
Kind |
6-275604 |
Oct 1994 |
JPX |
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Parent Case Info
This is a Divisional Application of Ser. No. 08/543,193, filed Oct. 13, 1995.
US Referenced Citations (17)
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EPX |
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6-328225 |
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Divisions (1)
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Number |
Date |
Country |
Parent |
543193 |
Oct 1995 |
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