Inconel 686 Introduction

Super alloys or high performance alloys have the capacity to function under very high temperatures and severe mechanical stress, and also where high surface stability is required. They have good creep and oxidation resistance, and can be produced in a variety of shapes.

Strengthening of super alloys is performed by solid-solution hardening, work hardening, and precipitation hardening. Super alloys contain a number of elements in a variety of combinations to achieve the desired result.

Inconel 686™ is a single phase Ni-Cr-Mo-W alloy that is primarily used in extremely corrosive applications, e.g. flue gas desulfurization systems and processing plants in which mixed acids are used. This alloy is also used in fields where localized pitting is difficult.

The following datasheet will provide more details about Inconel 686™.


Inconel 686 Alloy Steel Bar

INCONEL® alloy 686 (UNS N06686/W.Nr. 2.4606) is a single-phase, austenitic Ni-Cr-Mo-W alloy offering outstanding corrosion-resistance in a range of severe environments. Its high nickel (Ni) and molybdenum (Mo) provide good resistance in reducing conditions, and high chromium (Cr) offers resistance to oxidizing media. Molybdenum (Mo) and tungsten (W) aid resistance to localized corrosion such as pitting. Iron (Fe) is closely controlled to enhance properties. Low carbon (C) helps minimize grain boundary precipitation to maintain corrosion-resistance in the heat-affected zones of welded joints. Resistance to general, pitting and crevice corrosion increases with the alloying (Cr+Mo+W) content, and INCONEL alloy 686 scores higher than competitive materials. INCONEL alloy 686 is protected by U.S. patent 5,019,184.

Its matched composition welding products, designated as INCO-WELD® filler metals and welding electrode 686 CPT® also offer exceptional as-welded resistance to sulfuric or hydrochloric acids, to mixtures of the two, and to crevice or pitting corrosion in hot concentrated acid chloride solutions. These welding products are also used for dissimilar and overmatched welding applications.

Inconel® 686 offers excellent resistance to general corrosion, stress-corrosion cracking and to pitting and crevice corrosion in a variety of aggressive media. It’s high nickel and molybdenum content provide good resistance in reducing conditions while the high chromium content offers resistance to oxidizing media. Localized corrosion resistance is further enhanced by the addition of tungsten. Carbon content is restricted to help minimize grain boundary precipitation to maintain the corrosion resistance in the heat-effected zone of welded areas.

Inconel® 686 also proves to be well suited in handling mixed acid solutions containing high concentrations of halides and has shown good resistance to mixed acid media with pH levels of 1 or less, and chloride levels of over 100,000 ppm.

INCONEL alloy 686 is used for resistance to aggressive media in chemical processing, pollution control, pulp and paper manufacture, and waste management applications.

Inconel 686 Chemical Composition:

The following table shows the chemical composition of Inconel 686™.

ElementContent (%)
Nickel, Ni59
Chromium, Cr19-23
Molybdenum, Mo15-17
Iron, Fe≤ 5
Tungsten, W3.0-4.40
Manganese, Mn≤ 0.75
Phosphorous, P≤ 0.040
Sulfur, S≤ 0.020
Titanium, Ti0.020-0.25
Carbon, C≤ 0.010

Inconel 686 Physical Properties:

The physical properties of Inconel 686™ are outlined in the following table.

Density8.72 g/cm³0.315 lb/in³
Melting point1338-1380 °C2440-2520 °F

Inconel 686 Mechanical Properties:

The mechanical properties of Inconel 686™ are provided below.

Tensile strength721.9 MPa104700 psi
Yield strength (@strain 0.200%)364 MPa52800 psi
Elastic modulus207 GPa30000 ksi
Shear modulus77 GPa11200 ksi
Poisson’s ratio0.340.34
Elongation at break71%71%

Inconel 686 Thermal Properties:

The thermal properties of Inconel 686™ are given below.

Thermal expansion co-efficient (@21-100°C/69.8-212°F)11.97 µm/m°C6.650 µin/in°F