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Material: Inconel 600, 601, 625, 718
Type: Round bar,Square bar,Hex bar,Flat bar
Tolerance: H7 H9 H10 H11
Surface: Black or Bright or Pickling white
Diameter: 5~500mm
Length: ≦12M or As Per Client's Requirements.
Inconel round bars are solid cylindrical nickel-chromium superalloy products engineered for service in oxidising acids, chloride stress-corrosion environments, and temperatures up to 1 093 °C (2 000 °F).
Four principal grades cover the full spectrum of corrosion and strength: 600, 601, 625, 718.
Bar types include hot-rolled black, cold-drawn bright, forged, centreless-ground, peeled, and polished — each optimised for different tolerance and surface requirements.
Alloy 625 (PREN 48–51) is the premier choice for seawater and offshore chloride environments; Alloy 718 delivers the highest yield strength (1 034 MPa) via precipitation hardening.
Critical standards: ASTM B166 (600/601 rod & bar), ASTM B446 (625 rod & bar), ASTM B670 (718 bar), and AMS 5662/5663/5664.
Type | Round Bar Square Bar Hexagon Bar Flat Bar | ||
Surface | Black or Bright or Pickling white | ||
Standard | SUS, AISI, DIN | ||
Manufacture Technique | Hot Rolling, Cold-drawing | ||
Diameter | 5~500mm | ||
Length | ≦12M or As Per Client's Requirements. | ||
Diameter Tolerance | H7 H9 H10 H11 | ||
Material Grade | Inconel 600, 601, 625, 718 | ||
Inconel round bars are solid cylindrical products with a circular cross-section, manufactured from nickel-chromium superalloy families. Inconel is a registered trademark of Special Metals Corporation, covering a series of nickel-based alloys specifically engineered to survive extreme environments — from concentrated acids and chloride-rich seawater to continuous service at over 1 000 °C.
Unlike carbon steel or standard stainless steel, Inconel alloys rely on their high nickel content (typically ≥58%) to resist both reducing and oxidising media.
Round bars are the most versatile semi-finished form in nickel alloys. Their circular geometry provides uniform mechanical properties in every radial direction, which is essential for rotating shafts, valve stems, pump components, fasteners, and structural members that carry torsional loads. They serve as the starting stock for machining, forging, and cold-forming operations across aerospace, chemical processing, nuclear, oil & gas, and marine industries.
Inconel round bars are produced in several surface conditions and manufacturing routes. Each type optimises a different combination of dimensional tolerance, surface finish, mechanical strength, and cost. The table below summarises the six principal bar types and their defining characteristics.
Bar Type | Manufacturing Process | Typical Diameter | Surface | Tolerance | Best Application |
Hot-Rolled Black Bar | Hot rolling from billet at 1 000+ °C | 10–500 mm | Dark, rough oxide skin | ±2–3% | Forging stock, general machining, large-diameter shafts |
Cold-Drawn Bright Bar | Cold drawing through die at room temp. | 3–100 mm | Smooth, bright, scale-free | ±0.1–0.5% (h8–h11) | Precision machining, fasteners, pump shafts |
Forged Bar | Press/hammer forging of billet | 50–800 mm | Rough to semi-finished | ±2–4% | Large flanges, high-force components, pressure vessel forgings |
Centreless-Ground Bar | Centreless grinding of cold-drawn stock | 3–80 mm | Mirror-smooth, ultra-precise | ±0.01–0.05 mm (h6–h7) | Aerospace shafts, medical implants, high-speed spindles |
Peeled / Turned Bar | Rotary peeling/turning of hot-rolled bar | 20–200 mm | Clean, semi-bright | ±0.5–1 mm | Intermediate machining stock, valve stems |
Polished Bar | Mechanical polishing of cold-drawn bar | 3–100 mm | Decorative mirror finish (Ra < 0.4 μm) | ±0.1–0.3% | Architectural, marine hardware, decorative fasteners |
Source: ASTM B166-24 Section 5; ASTM B446-21; EN 10278:2020; Industrial bar processing references.
JN Alloy supplies Inconel round bars in four core grades, each engineered for a distinct set of corrosion, temperature, and strength requirements. The grade comparison below maps each alloy to its UNS designation, defining alloy feature, and primary industry application.
Grade | UNS | Family | Defining Feature | Max Service Temp. | Primary Industry |
Inconel 600 | N06600 | Ni–Cr–Fe | General-purpose Ni–Cr; excellent oxidation resistance | 1 093 °C | Chemical, nuclear, thermal processing |
Inconel 601 | N06601 | Ni–Cr–Fe+Al | Al addition gives superior spalling resistance | 1 260 °C | Furnace parts, thermal processing, aerospace |
Inconel 625 | N06625 | Ni–Cr–Mo–Nb | Mo+Nb yield outstanding chloride/acid resistance (PREN 48–51) | 980 °C | Offshore, seawater, chemical, aerospace |
Inconel 718 | N07718 | Ni–Cr–Fe+Nb+Ti | Precipitation-hardenable; ultra-high strength (YS 1 034 MPa) | 700 °C | Aerospace engines, gas turbines, O&G downhole |
Source: Special Metals Corporation; Haynes International; ASTM B166/B446/B408/B649/B670; ASM Handbook Vol. 1.
Grade | Ni | Cr | Fe | Mo | Nb+Ta | Al | Ti | Cu | C (max) |
600 | ≥72 | 14–17 | 6–10 | — | — | — | — | ≤0.5 | 0.10 |
601 | 58–63 | 21–25 | Bal. | — | — | 1.0–1.7 | — | ≤1.0 | 0.10 |
625 | ≥58 | 20–23 | ≤5 | 8–10 | 3.15–4.15 | ≤0.4 | ≤0.4 | — | 0.10 |
718 | 50–55 | 17–21 | Bal. | 2.8–3.3 | 4.75–5.50 | 0.65–1.15 | 0.20–0.80 | ≤0.3 | 0.08 |
Source: ASTM B166-24 (600/601); ASTM B446-21 (625); ASTM B670-03 (718); ASTM B408-21 (800/800H); ASTM B649-21 (825); Special Metals Corp. Technical Data Sheets.
Mechanical properties vary dramatically between solid-solution alloys (600, 601, 625,) and precipitation-hardenable alloys (718). The table below presents the minimum values specified by ASTM standards for rod/bar products at room temperature.
Grade | Condition | YS (MPa) | UTS (MPa) | Elong. (%) | Red. Area (%) | Hardness |
600 | Annealed | 240 | 550 | 30 | — | ≤195 HB |
601 | Annealed | 205 | 450 | 30 | — | — |
625 | Annealed | 414 | 827 | 30 | ≥40 | ≤200 HB |
718 | Age-hardened | 1 034 | 1 240 | 12 | ≥15 | ≥40 HRC |
Source: ASTM B166 (600/601); ASTM B446 (625); ASTM B670 (718); ASTM B408 (800/800H); ASTM B649 (825); AMS 5662/5663/5664 (718); Special Metals Corp. datasheets.
Correct material selection requires matching the alloy grade to the governing ASTM or AMS specification. Each standard defines the permissible chemical composition range, mechanical property minimums, heat treatment requirements, testing protocols, and dimensional tolerances. The table below maps every grade to its primary rod/bar standard, secondary forging/tube standard, and the applicable aerospace AMS number.
Grade | Rod/Bar Standard | UNS Covered | Forging Std. | Aerospace AMS | Product Form Scope |
600 | ASTM B166 | N06600, N06601, N06690 | ASTM B564 | AMS 5665 | Rod, bar, wire; seamless pipe (B167) |
601 | ASTM B166 | N06601 | — | AMS 5666 | Rod, bar, wire |
625 | ASTM B446 | N06625 | ASTM B564 | AMS 5666 | Rod, bar; seamless pipe (B444) |
718 | ASTM B670 | N07718 | ASTM B564 | AMS 5662/5663/5664 | Rod, bar; sheet/plate (B906); forging |
Source: ASTM International Standards Catalogue 2024; AMS Aerospace Material Specifications; *X-750 bar also specified under ASTM B166 UNS N07750 scope (select editions).
Additional Referenced Standards
ASTM A276/A276M — General specification for stainless and nickel alloy bars (supplementary reference)
ASTM B444 — UNS N06625 (625) seamless pipe and tube
ASTM B906 — UNS N07718 (718) plate, sheet, and strip
EN 10278 — Dimensions and tolerances of bright steel bars
EN 10088-3 — Stainless steels — Semi-finished products, bars, rods and sections (general reference)
NACE MR0175 / ISO 15156 — Sulphide stress cracking resistant materials for O&G (applicable to 625, 718)
Q: What is the difference between Inconel and Incoloy round bars?
A: Inconel grades (600, 601, 625, 718, X-750) are nickel-based alloys with ≥30% Ni, designed for extreme corrosion and high-temperature service. Incoloy grades (800, 800H, 800HT, 825) are iron-based alloys with 30–46% Ni, offering a more cost-effective balance of oxidation and moderate corrosion resistance for temperatures below ~816 °C. Inconel excels in the harshest environments; Incoloy excels where moderate performance at lower cost is acceptable.
Q: Which Inconel grade should I choose for seawater / offshore service?
A: Inconel 625 (UNS N06625). Its PREN of ~51 — derived from 22% Cr + 9% Mo — far exceeds any stainless steel, ensuring negligible pitting in seawater at temperatures up to 60 °C. It also meets NACE MR0175/ISO 15156 for sour service, making it the single grade that covers both chloride pitting and H2S cracking in offshore environments.
Q: Can Inconel 718 be used for high-strength fasteners in oil & gas?
A: Yes. Inconel 718 is the standard precipitation-hardenable nickel alloy for high-strength downhole fasteners, with age-hardened yield strength of 1 034 MPa and UTS of 1 240 MPa. It meets NACE MR0175/ISO 15156 (hardness ≤40 HRC) when properly heat-treated. The 4.75–5.50% Nb content enables age-hardening without loss of corrosion resistance.
Q: What bar surface finish should I specify for precision machining?
A: Centreless-ground (h6–h7 tolerance) for the highest precision (±0.01–0.05 mm), or cold-drawn bright (h8–h11) for general precision machining (±0.1–0.5 mm). Hot-rolled black bar requires rough machining first and is unsuitable for tight-tolerance components.
Q: What is the maximum operating temperature for each Inconel round bar grade?
A: 601: up to 1 260 °C. 600: up to 1 093 °C. 625: up to 980 °C. 718: up to 700 °C. 800H: up to 816 °C. X-750: up to 800 °C .
Q: Does JN Alloy provide mill test certificates for Inconel round bars?
A: Yes. All Inconel round bars are supplied with EN 10204 3.1 (or 3.2 upon request) Mill Test Certificates, documenting chemical composition, mechanical properties, heat treatment condition, and dimensional inspection results. ISO 9001:2015 certification governs the entire production and inspection process.
Q: How do Inconel round bars compare to Hastelloy for hydrochloric acid service?
A: For pure HCl, Hastelloy C-276 (16% Mo) outperforms Inconel 625 (9% Mo) at concentrations above 10% and temperatures above 60 °C. However, Inconel 625 is superior in chloride/oxidising environments where Hastelloy’s lower chromium content is a disadvantage. Selection depends on the specific acid concentration, temperature, and presence of oxidising impurities.
