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A core crush resistant prepreg for use in making a fiber reinforced composite panel structure is provided. The prepreg comprises a woven fabric consisting essentially of carbon fiber tow strands impregnated with a hardenable polymeric resin composition. Typically the fabric has an areal weight of fr

A core crush resistant prepreg for use in making a fiber reinforced composite panel structure is provided. The prepreg comprises a woven fabric consisting essentially of carbon fiber tow strands impregnated with a hardenable polymeric resin composition. Typically the fabric has an areal weight of from about 180 to about 205 grams per square meter. The prepreg has an average fiber tow aspect ratio of less than about 15.4, a prepreg thickness of at least about 0.245 mm, and a prepreg openness of at least about 1.2 percent but less than about 6.0 percent. Preferably, the resin composition is predominantly viscous in nature and has a tan δ value of between 0.9 and 2.0 at an elevated temperature between 70° C. and 140° C., and an average epoxy functionality of greater than 2.0. A method for evaluating core crush resistance properties of a prepreg is also provided. The method includes determining a fiber tow average aspect ratio of the prepreg, determining a prepreg thickness, and comparing said average fiber tow aspect ratio and prepreg thickness to a set of predetermined values.

대표청구항 ▼

A core crush resistant prepreg for use in making a fiber reinforced composite panel structure is provided. The prepreg comprises a woven fabric consisting essentially of carbon fiber tow strands impregnated with a hardenable polymeric resin composition. Typically the fabric has an areal weight of fr

A core crush resistant prepreg for use in making a fiber reinforced composite panel structure is provided. The prepreg comprises a woven fabric consisting essentially of carbon fiber tow strands impregnated with a hardenable polymeric resin composition. Typically the fabric has an areal weight of from about 180 to about 205 grams per square meter. The prepreg has an average fiber tow aspect ratio of less than about 15.4, a prepreg thickness of at least about 0.245 mm, and a prepreg openness of at least about 1.2 percent but less than about 6.0 percent. Preferably, the resin composition is predominantly viscous in nature and has a tan δ value of between 0.9 and 2.0 at an elevated temperature between 70° C. and 140° C., and an average epoxy functionality of greater than 2.0. A method for evaluating core crush resistance properties of a prepreg is also provided. The method includes determining a fiber tow average aspect ratio of the prepreg, determining a prepreg thickness, and comparing said average fiber tow aspect ratio and prepreg thickness to a set of predetermined values. i×N≤2×10-4. 2. The process of claim 1, wherein the steel composition further satisfies the following relationships: 15%≤Ni≤17% 6%≤Mo≤8% 8.75%≤Co≤13% 20%≤Ni+Mo≤27% Co×Mo≥50. 3. The process of claim 1, wherein the steel composition further satisfies the following relationships: 15%≤Ni≤21% 4.17%≤Mo≤8% 8.75%≤Co≤17.5% 22%≤Ni+Mo≤25% Co×Mo≥70. 4. The process of claim 1, wherein the steel composition further satisfies the following relationships: 17%≤Ni≤20% 4%≤Mo≤6% 13%≤Co≤17.5% 22%≤Ni+Mo≤25% Co×Mo≥70. 5. The process of claim 1, wherein the steel composition further satisfies the following relationships: 17%≤Ni≤20% 4.17%≤Mo≤6% 13%≤Co≤17% 20%≤Ni+Mo≤27% Co×Mo≥50. 6. The process of claim 1, wherein the degree of working is greater than 40%. 7. The process of claim 1, wherein the ASTM index is higher than 10. 8. The process of claim 1, wherein the hardening heat treatment comprises holding the strip or part between 600° C. and 700° C. for 30 seconds to 3 minutes. 9. A strip or part of maraging steel having a thickness of less than 1 mm, wherein the steel has a fine-grained structure with an ASTM index of higher than 8, and a composition that comprises, in % by weight based on total weight: 12%≤Ni≤24.5% 2.5%≤Mo≤12% 4.17%≤Co≤20% Al≤0.15% Ti≤0.1% N≤0.003% Si≤0.1% Mn≤0.1% C≤0.005% P≤0.005% H≤0.0003% O≤0.001% iron and impurities resulting from smelting, the steel composition also satisfying the following relationships: 20%≤Ni+Mo≤27% 50≤Co×Mo≤200 Ti×N≤2×10-4, the steel having an elastic limit after hardening of greater than 1850 MPa. 10. A transmission belt comprising a strip or part according to claim 9. 11. A support mesh for integrated circuits comprising a part according to claim 9. 12. The strip or part according to claim 9, wherein the steel composition further satisfies the following relationships: 15%≤Ni≤17% 6%≤Mo≤8% 8.75%≤Co≤13% 20%≤Ni+Mo≤27% Co×Mo≥50. 13. The strip or part according to claim 9, wherein the steel composition further satisfies the following relationships: 15%≤Ni≤21% 4.17%≤Mo≤8% 8.75%≤Co≤17.5% 22%≤Ni+Mo≤25% Co×Mo≥70. 14. The strip or part according to claim 9, wherein the steel composition further satisfies the following relationships: 17%≤Ni≤20% 4%≤Mo≤6% 13%≤Co≤17.5% 22%≤Ni+Mo≤25% Co×Mo≥70. 15. The strip or part according to claim 9, wherein the steel composition further satisfies the following relationships: 17%≤Ni≤20% 4.17%≤Mo≤6% 13%≤Co≤17% 20%≤Ni+Mo≤27% Co×Mo≥50. 16. The strip or part according to claim 9, wherein the ASTM index is higher than 10. 17. A process for manufacturing a strip or of a part cut out of a strip of cold-rolled maraging steel and hardened by a hardening heat treatment, wherein, before the hardening heat treatment is performed, the strip or the part is subjected to cold plastic deformation with a degree of working greater than 30% and the strip or the part is subjected to recrystallization annealing in order to obtain a fine-grained structure with ASTM index higher than 8, the chemical composition of the steel comprising in % by weight based on total weight: 12%≤Ni≤24.5% 2.5%≤Mo≤12% 4.17%≤Co≤20% Al≤0.15% Ti≤0.1% N≤0.003% Si≤0.1% Mn≤0.1% C≤0.005% S≤0.001% P≤0.005% H≤0.0003% O≤0.001%; and iron and impurities resulting from smelting, the chemical composition also satisfying the following relationships: 20%≤Ni+Mo≤27% 50≤Co×Mo≤200 Ti×N≤2×10-4, wherein after recrystallization annealing, the strip or the part is subjected to cold rolling with a reduction ratio of between 1% and 10%. 18. The process of claim 17, wherein the degree of working is greater than 40%. 19. The process of claim 17, wherein the ASTM index is greater than 10. 20. The process of claim 17, wherein the hardening heat treatment comprises holding the str