Incoloy alloy 800H/UNS N08810/W.Nr. 1.4958 ASTM B409 sheet ring tube

Overview

Incoloy Alloy 800H is a solid-solution, high-strength austenitic nickel-iron-chromium alloy with coarse grain and high creep strength. The chemical composition of the alloy mainly includes nickel, iron, chromium, and the addition of carbon, aluminum, titanium and other elements. Through a special solution treatment, Incoloy 800H has a significant increase in tensile strength above 600 ° C and exhibits excellent mechanical properties and corrosion resistance. It is mainly used in chemical, electric power and petrochemical industry superheater, reheater, high temperature heating, conversion cracking furnace tube and other aspects, and widely used in high temperature pressure structural parts. In addition, Incoloy 800H alloy has excellent corrosion resistance and resistance to stress corrosion cracking in water-based media at extremely high temperatures up to 500°C.

Limiting Chemical Composition, %

Nickel...................................................................................................................................................................................30.00-35.00

Chromium............................................................................................................................................................................19.00-23.00

Iron..........................................................................................................................................................................................39.50 min.

Carbon......................................................................................................................................................................................0.05-0.10

Manganese..............................................................................................................................................................................1.50 max.

Sulfur......................................................................................................................................................................................0.015 max.

Silicon.......................................................................................................................................................................................1.0 0max.

Copper......................................................................................................................................................................................0.75 max.

Aluminum.................................................................................................................................................................................0.15-0.60

Titanium.....................................................................................................................................................................................0.15-0.60

Physical Constants

Mechanical properties

Tensile strength: After a special solution treatment, the tensile strength of Incoloy 800H above 600 ° C is significantly improved. The minimum tensile strength is 450Mpa, the minimum yield strength is 175Mpa, and the minimum elongation is 30%.

Hardness: Its hardness range is between HB135-179.

Corrosion resistance: Incoloy 800H has a good resistance to reduction, oxidation, nitride medium corrosion and resistance to alternating REDOX medium corrosion properties. High metallurgical stability in high-temperature long-term applications.

Heat treatment: Incoloy 800H is held between 980-1150 ° C for 2 hours, followed by rapid water cooling.

Tensile Properties

Tensile properties and hardness of INCOLOY alloys 800H/800HT at high temperatures

Corrosion Resistance

Incoloy Alloy 800H is a typical Ni-Fe-Cr series steel, which is an iron-based heat-resistant alloy and a kind of superalloy. It has excellent corrosion resistance and can remain stable in a variety of corrosive media.

The high nickel content of the alloy makes it very resistant to stress corrosion cracking under water corrosion conditions. The high chromium content enhances its resistance to pitting and crevice corrosion cracking. In addition, Incoloy 800H has good corrosion resistance to nitric and organic acids, but limited corrosion resistance in sulfuric and hydrochloric acid. Point corrosion may occur in halides, but has good corrosion resistance in both oxidizing and non-oxidizing salts.

In addition, it has good corrosion resistance in water, steam and mixtures of steam, air and carbon dioxide. Therefore, Incoloy 800H is widely used in nitric acid condensers, steam heating tubes and heating element tubes.

Heating and Pickling

The heat treatment of Incoloy Alloy 800H mainly includes solution treatment and aging treatment. Solution treatment is to heat the material to a solution temperature, so that the alloying elements are uniformly dissolved in the matrix, and then quickly cooled to maintain the solution state. This process can improve the plasticity and toughness of the material and reduce hardness and strength, while helping to eliminate stress and phase transitions. In the solution treatment process, the diffusion rate of alloying elements will be accelerated, further improving the properties of the material.

Aging treatment is to heat the material to a certain temperature after solution treatment, keep it for a period of time, and then cool it quickly. This process re-precipitates the alloying elements to form a fine and uniform precipitated phase. The presence of these precipitated phases can improve the strength and hardness of the material while maintaining its good toughness. The temperature and time of aging treatment need to be reasonably selected according to the composition and requirements of the specific alloy to ensure the best results.

In addition to solution treatment and aging treatment, the heating and cooling rate during heat treatment is also an important factor affecting material properties. Excessive heating and cooling rates can cause stress and deformation of the material, affecting its performance. Therefore, the heating and cooling rates need to be strictly controlled during the heat treatment process to ensure the stable performance of the material.

The heat treatment process of Incoloy Alloy 800H can significantly improve its properties. Reasonable selection of temperature and time for solution treatment and aging treatment, as well as control of heating and cooling rates, enabled Incoloy Alloy 800H to have better heat resistance, creep resistance and corrosion resistance. In practical applications, heat treatment should be carried out according to specific requirements and process conditions to ensure that the performance of the material reaches the expected goal.

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