Alloy 59 Fasteners

Ultra-Pure Nickel-Chromium-Molybdenum Alloy – Highest PREN in its Class

Buy Alloy 59 (UNS N06059 / Werkstoff 2.4605 / ASTM B574) bolts, stud bolts, heavy hex nuts, socket cap screws, and custom CNC fasteners from Exotic Alloy. Alloy 59 is an ultra-pure nickel-chromium-molybdenum alloy containing approximately 23% Cr and 16% Mo with an aluminium deoxidised, tungsten-free and very low carbon, silicon and sulfur chemistry, giving it the highest pitting resistance equivalent number of any commercial Ni-Cr-Mo alloy at roughly 76.

Exotic Alloy manufactures Alloy 59 fasteners conforming to ASTM B574, ASME SB-574, VdTÜV 505 and NACE MR0175 / ISO 15156-3 in metric M6–M100 and imperial ¼"–4" sizes with full EN 10204 3.1 material test certificates for flue gas desulphurisation, chemical processing, waste incineration and sour gas applications.

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Technical Data

Alloy 59 Specifications

Chemical Composition — Alloy 59 (wt. %)

Element	Ni	Cr	Mo	Fe	Al	Co	Cu	Si	C
Min %	58.00	22.00	15.00	–	0.10	–	–	–	–
Max %	Balance	24.00	16.50	1.50	0.40	0.30	0.50	0.10	0.010

Mechanical Properties — Alloy 59

Condition	UTS (MPa)	YS 0.2% (MPa)	Elongation (%)	Hardness
Solution Annealed (ASTM B574 Minimum)	≥ 690	≥ 310	≥ 40	≤ 100 HRB
Solution Annealed (Typical Bar)	750	360	55	88 HRB
Cold Drawn / Stress Relieved	880–1050	600–800	15–25	24–31 HRC
Hot Finished Forged Bar	720–820	330–400	45–55	≤ 220 HB

Physical Properties

Density	8.60 g/cm³
Melting Range	1310–1360°C (2390–2480°F)
Specific Heat Capacity	410 J/kg·K at 20°C
Thermal Conductivity	10.4 W/m·K at 100°C
Thermal Expansion	12.4 µm/m·°C (20–100°C)
Electrical Resistivity	1.28 µΩ·m

Equivalent Grades & Standards

UNS	Werkstoff / DIN	EN Designation	Common Name
N06059	2.4605	NiCr23Mo16Al	Alloy 59

Key Specifications: ASTM B574 (Rod/Bar) / ASTM B575 (Plate & Sheet) / ASTM B619, B622, B626 (Tube) / ASTM B564 (Forgings) / ASTM B462 (Flanges) / VdTÜV 505 / NACE MR0175

Machinability: Alloy 59 is tungsten-free, which makes it slightly less abrasive than C-276 and C-22, but it still work-hardens rapidly. Use rigid setups, sharp positive-rake carbide tooling at 20–35 SFM, heavy positive feeds and generous depth of cut with continuous flood coolant. Light finishing passes riding on work-hardened metal should be avoided.

Welding: Alloy 59 is welded by GTAW, GMAW, SMAW and plasma arc using matching ERNiCrMo-13 filler wire or ENiCrMo-13 electrodes. Its exceptionally low carbon, silicon, sulfur and phosphorus content gives excellent resistance to hot cracking and to grain-boundary precipitation, so welds retain essentially base-metal corrosion resistance without post-weld heat treatment. Pre-heat is not required.

Forging: Hot forge between 1100–1200°C (2010–2190°F), finishing above 980°C (1800°F) and reheating between passes as required. The ultra-low impurity chemistry gives Alloy 59 notably good hot ductility. Cold forging and cold heading are practicable in smaller diameters with intermediate anneals.

Heat Treatment: Solution anneal at 1100–1180°C (2010–2155°F) followed by rapid water quench. The alloy has excellent thermal stability and is highly resistant to the formation of embrittling intermetallic phases. Alloy 59 is not age-hardenable; strengthening above the annealed condition is achieved only by cold work, limited to 40 HRC maximum for NACE MR0175 sour service.

Alloy 59 offers the highest general and localised corrosion resistance of the commercial nickel-chromium-molybdenum alloys. Its pitting resistance equivalent number of approximately 76 places it above both C-276 and C-22 for chloride pitting and crevice corrosion, with critical crevice corrosion temperatures among the highest recorded for any alloy. It resists sulfuric, hydrochloric, phosphoric, formic and acetic acids, wet chlorine, hypochlorite, and contaminated mixed acids. The aluminium-deoxidised, tungsten-free, ultra-low-impurity chemistry also gives it outstanding resistance to intermetallic phase formation and to intergranular attack in welded assemblies.

Key Characteristics

Highest pitting resistance equivalent number of the Ni-Cr-Mo family — approximately 76.
Outstanding resistance to chloride pitting and crevice corrosion.
Ultra-low carbon, silicon and sulfur for excellent weld-zone performance.
Tungsten-free chemistry resists embrittling intermetallic phase formation.
NACE MR0175 / ISO 15156-3 qualified for sour hydrocarbon service.

Typical Applications

Flue gas desulphurisation: absorber, quench and stack liner bolting.
Chemical processing: mixed acid reactor and heat exchanger fasteners.
Waste incineration: scrubber and flue gas cleaning plant hardware.
Sour gas and offshore: NACE MR0175 qualified flange and wellhead bolting.
Pharmaceutical and fine chemicals: high-purity reactor closure fasteners.

Alloy 59