Comparison of Nickel 600 alloy and Nickel 690 grade

01.

Both Nickel 600 and Nickel 690 are high-performance nickel alloys, but the main difference lies in their chromium content. Nickel 690 has a significantly higher chromium content (up to 31%, compared to 14-17% for Nickel 600) and a lower nickel content (minimum 58%, compared to a minimum of 72% for Nickel 600). This composition makes Nickel 690 perform better in corrosive environments, especially in resistance to oxidizing acid corrosion, making it suitable for nuclear power applications, such as steam generator piping, where stress corrosion cracking is a concern. Nickel 600 is a standard and versatile alloy suitable for general high-temperature and corrosive applications.

02.

What are the applications of INCONEL 690 alloy?

INCONEL 690 alloy is widely used in steam generator tubes, baffles, tube sheets, and various hardware components in nuclear power plants.

What is Nickel Alloy 600?

Nickel Alloy 600, also known as Inco Nickel Alloy 600, is a nickel-chromium alloy that performs exceptionally well in high-temperature, high-pressure applications in seawater, open-air environments, and acidic and alkaline conditions.

Its unique properties stem from its chemical composition: it contains at least 72% nickel-cobalt alloy, 14-17% chromium, 6-10% iron, and trace amounts of manganese, silicon, carbon, copper, and sulfur. This combination enhances its corrosion resistance and high-temperature resistance.

Inconel 690 Overview

Inconel 690 is a nickel-chromium alloy designed for resistance to high-temperature oxidation, high-temperature corrosion, and corrosive aqueous environments. Its extremely high chromium content (approximately 30%) provides superior resistance to oxidizing chemicals and high-temperature gas corrosion compared to other Inconel alloys.

Gnee Steel supplies a wide range of Inconel 600 and 690 alloys, including plates, sheets, bars, tubes, wires, and custom-machined parts. With decades of experience in specialty alloys, our team ensures that every batch meets stringent ASTM and international quality standards, making us a trusted partner for industries worldwide.

Chemical Composition Comparison: Inconel 690 vs. Inconel 600

Element	Inconel 690 (%)	Inconel 600 (%)	Key Differences & Impact Analysis
Nickel (Ni)	≥ 58	~72	Fundamental Difference. 600 has a significantly higher nickel content, providing a more "pure" nickel matrix, which gives it inherent advantages in reducing environments and against stress corrosion.
Chromium (Cr)	27 - 31	14 - 17	The Most Significant Difference. The chromium content in 690 is nearly double that of 600, making it exceptionally resistant to oxidizing environments (e.g., hot air, nitric acid) and stress corrosion.
Iron (Fe)	7 - 11	6 - 10	Similar levels in both, acting as a minor element for structural balance.
Carbon (C)	≤ 0.05	≤ 0.15	Key Difference. The carbon content in 690 is controlled to a very low level to minimize carbide precipitation, thereby significantly enhancing resistance to intergranular corrosion and intergranular stress corrosion cracking.
Silicon (Si)	≤ 0.5	≤ 0.5	Same level, contributes to oxidation resistance in both.
Manganese (Mn)	≤ 0.5	≤ 1.0	Both act as deoxidizers; 600 has a slightly higher upper limit.
Copper (Cu)	≤ 0.5	≤ 0.5	Residual element, same level.
Sulfur (S)	≤ 0.015	≤ 0.015	Harmful impurity, strictly controlled in both.
Aluminum (Al)	≤ 0.5	-	Residual in 690, aids oxidation resistance. Typically not specified in standard 600 composition.
Titanium (Ti)	≤ 0.5	-	Residual in 690, aids grain boundary stability. Typically not specified in standard 600 composition.

Mechanical Properties Comparison: Inconel 690 vs. Inconel 600

Property	Inconel 690	Inconel 600	Comparative Notes
Density	8.19 g/cm³	~8.47 g/cm³ (Typical)	Both are dense nickel-chromium alloys, with Inconel 600 being slightly denser.
Melting Range	1343 - 1377 °C	~1370 - 1425 °C (Typical)	Inconel 600 has a slightly higher melting point range.
Tensile Strength (Room Temp)	620 - 760 MPa	550 - 990 MPa	Inconel 600 shows a wider strength range, achievable through various cold work conditions. Inconel 690's range is typical for the annealed condition.
Yield Strength (0.2% Offset)	240 - 310 MPa	~240 MPa (Annealed, min.)	Inconel 690 can achieve a higher typical yield strength in its standard annealed form compared to the minimum for annealed Inconel 600.
Elongation	30 - 45 %	30 - 40 %	Both alloys exhibit excellent ductility in the annealed condition, with Inconel 690 having a slightly higher potential maximum.
Hardness	70 - 80 HRB	~65 - 85 HRB (Annealed)	Hardness is comparable in the annealed state for both alloys, varying with exact processing.
Oxidation Resistance	Excellent up to 1200 °C	Excellent up to ~1175 °C	Due to its higher Chromium content, Inconel 690 offers marginally superior oxidation resistance at the very high end of the temperature spectrum.

Feature	Nickel 600	Nickel 690
Primary Composition	Minimum 72% Nickel, 14-17% Chromium	Minimum 58% Nickel, 27-31% Chromium
Key Advantage	General-purpose high-temperature and corrosion resistance	Superior corrosion resistance, especially in oxidizing acids
Corrosion Resistance	Good in a wide range of corrosive environments	Excellent resistance to oxidizing acids like nitric acid; highly resistant to stress corrosion cracking in nuclear power environments
Typical Applications	Boilers, heaters, gas turbines, general chemical processing	Nuclear steam generator tubing, pickling operations, reprocessing nuclear fuels