Hiduron Density

The Hiduron modulus of 130 to 135 GPa is roughly two-thirds of the carbon-steel modulus (207 GPa) and roughly 70 percent of the 316L stainless modulus (193 GPa). The practical effect on bolted-joint design is twofold. First, a Hiduron stud or bolt elongates more than a steel bolt of the same dimensions at the same preload, which means the joint stiffness drops and the bolt-to-flange stiffness ratio shifts. Second, the torque required to develop a given preload drops because the bolt elongation against rotation is greater. The torque chart captures the Hiduron-specific torque values that account for the lower modulus and the ductile thread engagement that the Cu-Ni-Al matrix offers. The bolt-flange stiffness shift also means that a Hiduron-bolted joint absorbs cyclic loads differently from a steel-bolted joint, which affects the fatigue-life estimate on subsea, splash-zone and naval bolting where the cyclic-load duty is decisive.

The Hiduron expansion coefficient of 16.5 x 10^-6 / K matches 316L stainless closely (17.5 x 10^-6 / K) and differs from carbon steel (12 x 10^-6 / K) by roughly 4 x 10^-6 / K. For Hiduron bolts clamping a carbon-steel flange, the differential expansion across the 0 to 80 deg C service envelope produces a preload swing that the joint designer must account for. For Hiduron bolts clamping a stainless or copper-alloy flange, the differential is small enough that the preload swing stays inside the design margin. The standard practice on offshore platform riser bolting is to spec the bolt material to match the flange material expansion within the service envelope, which is one of the reasons Hiduron 191 is specified together with Cu-Ni-Al or 70/30 cupronickel flange material.

Every Hiduron 130 and Hiduron 191 stock and finished fastener ships with EN 10204 type 3.1 mill test certificate as standard. Type 3.2 third-party witness by Lloyd's Register, DNV, BV, SGS or TUV is supplied on call-out and is standard practice on naval and subsea procurement orders. The certificate carries the melt heat number, full chemical analysis to the controlling specification, solution-anneal plus age cycle parameters, tensile and yield results, hardness, Charpy V impact result where called out, and the dimensional report. For Hiduron 191 sour-service orders, an additional NACE MR0175 hardness certificate confirms that every test piece reads below the 286 HBW (28 HRC) limit.

TorqBolt supplies Hiduron 130 (UNS C72400, DTD 900/4805) and Hiduron 191 (UNS C72420, NES 835, DEF STAN 02-835, DOD-C-24676) in round bar, stud bolts, hex bolts, heavy hex bolts, nuts, washers, forgings and machined components. Standard fastener lead time is 4 to 8 weeks from order, subsea machined components quote project-specific lead time. Send an enquiry through TorqBolt Contact with the controlling specification, the form factor, the size envelope and the certification level (3.1 default, 3.2 on call-out, NACE on call-out).

Request a Quote on Hiduron 130 and Hiduron 191 Bolting Stock and Fasteners

Q. What is the Hiduron density?
Hiduron 130 reads 8.85 g/cm3 and Hiduron 191 reads 8.65 g/cm3 at room temperature, calculated from the chemistry. The mass-per-metre on 25 mm round bar works out to roughly 4.35 kg/m on Hiduron 130 and 4.25 kg/m on Hiduron 191.

Q. What is the Hiduron modulus of elasticity?
135 GPa on Hiduron 130 and 130 GPa on Hiduron 191. This is roughly two-thirds of the carbon-steel modulus and 70 percent of 316L stainless, which means Hiduron bolts develop the same preload at lower torque.

Q. What is the Hiduron thermal expansion coefficient?
16.5 x 10^-6 / K across the room-temperature to 300 deg C range on both grades. This matches 316L stainless closely and exceeds carbon steel by roughly 4 x 10^-6 / K.

Q. What is the Hiduron thermal conductivity?
26 W/m.K on both grades, which is roughly half the conductivity of pure copper and comparable to 70/30 cupronickel. The conductivity is high enough that local heat input during welding or machining diffuses quickly through the section.