Hiduron Machinability

On the pre-aged Hiduron 130 and 191 the chip breaks cleanly into 50 to 80 mm spiral sections at the recommended feed and depth, which protects the tool tip and clears the cutting zone reliably under flood coolant. On the as-solutioned condition the chip runs continuous and stringy, wraps the tool and loads the cutting edge; for this reason the standard route is to age before finishing operations. Tool wear is dominated by abrasive wear on the cutting edge from the gamma-prime precipitate; coated carbide (TiAlN, AlTiN) holds the edge longer than uncoated carbide, and PCD inserts can be used on long-run production where the marginal cost is justified. Built-up edge on the cutting face is suppressed by the flood coolant; dry cutting is not recommended on Hiduron because BUE forms within minutes and the surface finish degrades.

The standard surface finish on a finish-turned Hiduron bar is Ra 0.8 to 1.6 micrometres at the recommended cutting parameters with a 0.4 mm nose-radius insert. For threading, the standard practice is single-point turning rather than die-cutting, with the thread profile finished to the controlling standard (DIN 13 / ISO 261 metric, ASME B1.1 Unified). Rolled threads are also produced for the high-volume fastener lines (M12 to M24 stud bolts, hex bolts) and deliver a higher fatigue endurance than cut threads because the thread root is work-hardened during rolling rather than cut through the matrix.

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 machinability rating?
Roughly 30 percent of free-machining brass on Hiduron 130 in the aged condition, and roughly 25 percent on Hiduron 191 aged. The pre-aged condition machines better than the as-solutioned condition because the precipitate breaks the chip cleanly.

Q. What cutting speed should I use on Hiduron?
Vc 60 to 100 m/min for turning with coated carbide (TiAlN, AlTiN) inserts. Vc 30 to 50 m/min for HSS-Co tooling. Flood coolant is required to suppress built-up edge.

Q. Should I age Hiduron before or after machining?
For finished fasteners machine in the solution-annealed condition and age after machining to the finished dimension. For high-tolerance machined components age before machining and tighten the cutting parameters.

Q. Are rolled threads or cut threads preferred on Hiduron?
Rolled threads on the high-volume fastener lines (M12 to M24) deliver higher fatigue endurance because the thread root is work-hardened during rolling. Cut threads (single-point turning) are standard on larger sizes and custom thread profiles.