Other ultra-high-strength steels, such as AerMet alloys, are not as machinable because of their carbide content. In the sport of fencing, blades used in competitions run under the auspices of the Fédération Internationale d'Escrime are usually made with maraging steel. Maraging blades are superior for foil and épée because crack propagation in maraging steel is 10 times slower than in carbon steel, resulting in less frequent breaking of the blade and fewer injuries. Stainless maraging steel is used in bicycle frames (e.g. Reynolds 953 introduced in 2013) and golf club heads. It is also used in surgical components and hypodermic syringes, but is not suitable for scalpel blades because the lack of carbon prevents it from holding a good cutting edge. American musical instrument string producer Ernie Ball has made a specialist type of electric guitar string out of maraging steel, claiming that this alloy provides more output and enhanced tonal response. The production, import, and export of maraging steels by certain entities, such as the United States, is closely monitored by international authorities because it is particularly suited for use in gas centrifuges for uranium enrichment; lack of maraging steel significantly hampers the uranium-enrichment process. Older centrifuges used aluminum tubes, while modern ones use carbon fiber composite. Physical properties Density: 8.1 g/cm3 (0.29 lb/in3) Specific heat, mean for 0–100 °C (32–212 °F): 452 J/kg·K (0.108 Btu/lb·°F) Melting point: Thermal conductivity: 25.5 W/m·K Mean coefficient of thermal expansion: 11.3×10−6 K−1 (20.3×10−6 °F−1) Yield tensile strength: typically Ultimate tensile strength: typically . Grades exist up to Elongation at break: up to 15% KIC fracture toughness: up to 175 MPa·m Young's modulus: Shear modulus: Bulk modulus: Hardness (aged): 50 HRC (grade 250); 54 HRC (grade 300); 58 HRC (grade 350) See also Aermet USAF-96 and Eglin steel (Inexpensive maraging steels with less nickel and other expensive materials.) References External links Maraging steel data sheets Steels