Haynes 230 Alloy | N06230 | 2.4733 | 1150°C Creep Strength | Fushun Metal

Haynes 230 / N06230 / 2.4733 — Introduction

Haynes 230, designated UNS N06230 and Werkstoff Nr. 2.4733, is a solid-solution-strengthened nickel-chromium-tungsten-molybdenum alloy that represents the performance ceiling for wrought, non-age-hardenable high-temperature structural materials. Developed by Haynes International, it combines three complementary strengthening mechanisms—high-tungsten solid-solution hardening (nominally 14% W), controlled M₆C and M₂₃C₆ carbide distributions at grain boundaries, and a deliberate lanthanum microalloying addition (0.005–0.05%) that dramatically enhances the adherence and self-healing capability of the protective chromia scale—to deliver the highest combination of long-term creep strength, oxidation resistance, and microstructural stability available in a fabricable, weldable nickel alloy. Continuous service is rated to 1150°C in oxidizing atmospheres, and the alloy retains useful load-bearing capability to 1205°C. Haynes 230 is the only commercial wrought alloy that satisfies ASME Section VIII Division I and Section I Code Case 2063-3 for pressure-boundary service up to 900°C, confirming its long-term creep-rupture database and establishing it as the statistically qualified material of choice for high-temperature pressure vessels, industrial furnace hardware, gas turbine combustion-section components, and nitric acid catalyst support grids operating beyond the capability of stainless steels, iron-nickel-chromium alloys, and even conventional nickel-chromium grades such as Hastelloy X and Alloy 625.

At Fushun Metal, Haynes 230 is manufactured through a fully integrated triple-melt route under one roof. VIM primary melting under high vacuum is essential for the precise recovery of lanthanum—a rare-earth element with a high affinity for oxygen that would be lost to slag in air-melted heats—while also ensuring homogeneous distribution of the 14% tungsten addition, which is prone to gravitational segregation in less controlled melting processes. The VIM electrode undergoes VAR, where controlled directional solidification eliminates macro-segregation of tungsten and molybdenum, producing chemically homogeneous electrode stock essential for the microstructural stability and consistent creep properties that define this alloy’s performance advantage. For mission-critical applications—ASME Section I and VIII pressure-boundary components, aerospace combustion hardware, and ammonia burner catalyst grids—we deploy PESR as the final stage, achieving deep desulfurization and oxide refinement through argon-shielded reactive slag chemistry for maximum thermal-fatigue resistance and creep ductility.

Every heat is processed, solution-annealed, quenched, and tested within Fushun Metal’s certified quality management system—ISO 9001 for manufacturing process control and AS9120B for aerospace distribution traceability. Solution annealing is performed at 1177–1246°C followed by rapid water quenching to dissolve all carbides and produce the clean, recrystallized microstructure that develops its optimal creep-strengthening carbide distribution during service. Full digital traceability links each production lot from melt heat number through remelt sequence to final annealing batch. Standard deliverables include room-temperature and elevated-temperature tensile testing, stress-rupture testing per ASTM E139, grain size verification per ASTM E112, ultrasonic inspection, and chemical re-verification by optical emission and LECO combustion analysis. Mill test certificates to EN 10204 3.1 or 3.2 accompany every shipment.

Equivalent Grades of Haynes 230 Across International Standards

Haynes 230 is codified under multiple national and international specification systems. The table below maps its designations and governing standards across major markets. Fushun Metal certifies to all listed specifications and can dual-certify heats where required.

Applications of Haynes 230

Haynes 230 is the alloy of choice when long-term creep life, oxidation resistance, and microstructural stability must all be simultaneously maximized at temperatures above 980°C—a regime where most commercial heat-resistant alloys fail through a combination of oxide spallation, grain coarsening, and precipitate over-aging. Its ASME code qualification makes it the only non-age-hardenable wrought alloy legally permissible for pressure-boundary components above 900°C in many jurisdictions.

Haynes 230 — Supply Range by Fushun Metal

Fushun Metal stocks and processes Haynes 230 across all major mill forms from a single integrated facility. Our in-house 6000-ton hydraulic open-die press, 1800-ton precision radial forger (GFM), and multi-stand 850/550/350/250 rolling mills enable a broad dimensional envelope without outsourcing—ensuring uninterrupted lot traceability from melt to delivery under ISO 9001 and AS9120B. All material is supplied in the solution-annealed condition per AMS 5878 / AMS 5839 (typically 1177–1246°C, rapid water quench) to dissolve all carbides and produce optimal grain structure. The alloy’s lower-than-average coefficient of thermal expansion (CTE ~12.4 μm/m·°C) reduces thermal stress in fabricated assemblies compared to most nickel alloys. Hot-working: 1177°C; cold-working requires intermediate annealing. Welding: ERNiCrMo-1 (230-W) filler, GTAW/GMAW/resistance welding. Mill test certificates to EN 10204 3.1 or 3.2.

Chemical Composition of Haynes 230 — AMS 5878 / ASTM B435

All heats produced by Fushun Metal are melted via VIM+VAR or VIM+PESR and verified against the composition limits below by optical emission spectrometry and LECO combustion analysis. Full chemical certificates are issued with every shipment under ISO 9001 and AS9120B quality management. The four defining compositional features are: 14% tungsten for solid-solution strengthening retained to temperatures exceeding 1000°C; 22% chromium for chromia-scale oxidation protection to 1150°C; lanthanum (0.005–0.05%) as a reactive-element dopant that anchors the chromia scale and eliminates oxide spallation during thermal cycling; and controlled carbon (0.05–0.15%) that forms a thermally stable, uniformly distributed M₆C/M₂₃C₆ carbide network at grain boundaries during service, pinning grain boundaries against coarsening for tens of thousands of hours.

Mechanical Properties of Haynes 230 — Per Product Form & Temperature

Haynes 230 is a solid-solution and carbide-strengthened alloy; all properties are developed through solution annealing at 1177–1246°C followed by rapid water quenching. The alloy is not hardenable by precipitation heat treatment. At room temperature, the values below represent minimum guaranteed properties per AMS 5878 (sheet) and AMS 5839 (bar). The elevated-temperature tensile data and stress-rupture data are typical values for design reference. Haynes 230’s exceptional long-term creep strength relative to other non-age-hardenable alloys derives from the dense, thermally stable M₆C carbide distribution that develops progressively at grain boundaries during elevated-temperature service—a self-optimizing microstructure that improves with time rather than degrading through over-aging.

Fushun Metal performs all solution annealing in-house under calibrated furnace controls with rapid water-quench capability. Annealing at temperatures below the solution range produces partial carbide precipitation that marginally affects strength and ductility. The alloy’s lower CTE (~12.4 μm/m·°C, versus ~15 μm/m·°C for most austenitic grades) is a significant design advantage, reducing thermal stress in constrained components. Welding: ERNiCrMo-1 (AWS A5.14 / 230-W) filler wire for GTAW; matching electrodes for SMAW. Post-weld solution annealing is recommended for ASME pressure-boundary service to restore full creep properties across the weld joint.

Physical constants: Density 8.97 g/cm³; Melting range 1301–1371°C; Hardness ≤25 HRC (annealed condition); Modulus of elasticity 211 GPa at 20°C; Thermal conductivity 8.9 W/m·K at 20°C; Coefficient of thermal expansion 12.4 μm/m·°C (20–100°C). Continuous maximum service temperature: 1150°C in oxidizing atmospheres. ASME Code Case 2063-3 design stress allowables available to 900°C. The alloy is non-magnetic.