Claims
- 1. A process for the production of tools from alloy steel or stellites, comprising preparing from alloy steel powder a starting material with 30% by volume of carbidic and/or boridic precipitated phase, hot-working the powder of alloy steel below the transformation temperature with an alpha/gamma phase transformation isothermally or in the austenitic state, or hot-working the stellite powder at 700.degree. to 1000.degree. C., so that an equiaxial structure of the hot-worked starting material is obtained with a matrix grain size of 1 to 3 micrometers and a precipitated phase grain size of 0.2 to 1 micrometers, and subsequently superplastically deforming the hot-worked material.
- 2. A process according to claim 1, wherein powder-metallurgical tool steels and stellites are superplastically formed at temperatures of about 0.5 to 0.7 Tm and then continuously cooled.
- 3. A process according to claim 2, wherein the working temperature during preparing the starting material of alloy steel is from 900.degree. to 650.degree. C.
- 4. A process according to claim 1, wherein the stellitic starting material is hot-formed in the course of continuous cooling from 1000.degree. to 760.degree. C.
- 5. A process according to claim 2, wherein the deformation resulting from superplastically forming is more than 30% and the elongation amounts to some hundreds percent.
- 6. A process according to claim 5, wherein the deformation resulting from superplastically forming is up to 800%.
- 7. A process according to claim 1, wherein grain boundary slip and dynamic recrystallisation at 600.degree. to 700.degree. C. occur during hot-forming.
- 8. A process according to claim 1, wherein the superplastic forming is at a temperature below the secondary recrystallisation and grain growth temperature.
- 9. A process according to claim 1, wherein the alloy steels are superplastically formed at 650.degree. to 780.degree. C.
- 10. A process according to claim 8 wherein the rate of deformation .epsilon.=10.sup.-3 to 10.sup.-1 s.sup.-1.
- 11. A process according to claim 8, wherein the elongation rate exponent m=from 0.4 to 0.5.
- 12. A process according to claim 8, wherein the elongation rate exponent m=from 0.35 to 0.4 for stellites.
- 13. A process according to claim 8, wherein the shaped article is subjected to grain coarsening annealing.
Priority Claims (1)
Number |
Date |
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3544759 |
Dec 1985 |
DEX |
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Parent Case Info
This is a continuation of Ser. No. 07/267,640 filed Nov. 3, 1988, abandoned, which is a continuation of Ser. No. 06/942,542, filed Dec. 16, 1986, abandoned.
US Referenced Citations (3)
Foreign Referenced Citations (2)
Number |
Date |
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2206632 |
Sep 1976 |
DEX |
3346089 |
Jul 1985 |
DEX |
Non-Patent Literature Citations (1)
Entry |
H. Ruhfus, "Warmebehandlung der Einsatzstoffe", 1958, pp. 75 to 78. |
Continuations (2)
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Number |
Date |
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Parent |
267640 |
Nov 1988 |
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Parent |
942542 |
Dec 1986 |
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