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Incoloy 800H Welding For 800 H/HT use below 787°C, and weld with wire 82 (ER NiCr-3). R A 330-04 (N08334) wire has a matching coefficient of thermal expansion and higher strength. If maximum mechanical strength is desired, it is best to use wire 617 (ERNiCrCoMo-1) or electrode 117 (ENiCrCoMo-1).

In order to avoid cracking at grain boundaries due to stress relaxation that may occur in 800H/HT welded parts above 538°C, a post-weld heat treatment is required at 899°C, with a holding time of one hour for every 25 mm of material thickness (at least half an hour/25 mm of thickness), followed by air-cooling.

The corrosion resistance of Incoloy 800H.

800H is resistant to many corrosive media. Its high nickel content gives it good resistance to stress corrosion cracking in aqueous corrosive conditions. The high chromium content gives it better resistance to pitting and crevice corrosion cracking. The alloy has good resistance to nitric and organic acid corrosion, but limited resistance to sulphuric and hydrochloric acids. There is good corrosion resistance in oxidizing and non-oxidizing salts, except in halides where pitting corrosion is possible. It also has good corrosion resistance in water, vapor, and mixtures of steam, air, and carbon dioxide.

Strengthening Mechanism of Incoloy800H Alloy

In order to achieve excellent corrosion resistance and mechanical properties of Incoloy 800H alloys, it is necessary to add a variety of alloying elements to improve the corrosion resistance of the alloy and strengthen the austenite matrix.

Solid Solution Strengthening

Solid solution strengthening of Incoloy800H alloy is to add Fe, Cr, and other alloying elements to the matrix to form single-phase austenite, and the atomic radius of these elements is different from that of Ni, which produces an aberrant stress field within the crystal, hindering the movement of dislocations, thereby increasing the strength of the alloy. Because Ni and Fe, Cr, and other elements can form an infinite solid solution, the austenite matrix can be solidly dissolved into a large number of Fe, and Cr elements without phase transition.

Precipitation strengthening

Precipitation strengthening in Incoloy800H alloy plays an important role, γ ‘phase is an important strengthening phase in Incoloy800H alloy, for the FCC structure, and the matrix is a co-grid relationship. In practice, Ti atoms in the γ’ phase often replace some of the Al atoms to form Ni3(Al, Ti) reinforced phase. Due to the low interfacial energy between this phase and the austenitic matrix, the γ’-strengthened phase usually maintains high organizational stability [26]. In addition, the γ’ phase is able to strengthen the austenitic matrix through its interaction with the dislocation motion of the Al and Ti contents and the effect of the solid solution treatment on the organization and properties of Incoloy800H alloys (bypassing and cutting particle mechanisms), while the inherent plasticity of the γ’ phase avoids the second phase from acting as a source of crack initiation.

What are the properties of INCONEL alloy C276?

Nickel alloys need to work hard in extreme environments containing corrosive acids and other aggressive media. Even under the harshest conditions, INCONEL alloy C-276 is a popular choice. Here, we look at its properties and why they are suitable for these harsh environments.

There are many factors to consider when choosing the right material for harsh industrial environments. You need to know what kind of corrosive media will be present, what the operating temperature range is, and what loads the material will be subjected to. In a harsh situation, the material will need to be able to operate in some of the most corrosive conditions on earth, at high temperatures and high pressures.

Finding an alloy that can survive in such extreme environments is not an easy task. INCONEL C-276 alloy is a material worth considering due to its excellent corrosion resistance to a wide range of aggressive media. It is widely used in a variety of different industrial applications and is considered to be one of the most versatile options available in harsh environments. As a supplier of nickel alloys, Shanghai Makan Alloys has a comprehensive understanding of each material and a wealth of experience in the properties, characteristics, and applications of this technologically leading alloy.

1. Alloy C276 Main Characteristics
INCONEL Alloy C-276 is used in harsh environments due to its nickel alloy properties. It is a nickel-chromium superalloy with a high molybdenum content (15-17%). It is also possible to control the tungsten and iron content and to strictly limit the carbon content. The low carbon content minimizes carbide precipitation during heat treatment and welding. This means that the alloy retains its excellent resistance to pitting and crevice corrosion when used in welded structures. In other materials, the weld zone is weakened by heat during the welding process and is, therefore more resistant to corrosion.INCONEL alloy C-276 is sometimes covered with lower alloyed materials in the weld zone to provide additional protection and even higher performance in industrial applications.

The material’s corrosion resistance is one of its main highlights. Even in very harsh environments, it resists general corrosion such as stress corrosion cracking, pitting, and crevice corrosion very well. It is also extremely resistant to sulfuric, hydrochloric, and phosphoric acids. Highly oxidizing, neutral, and acidic chlorides; as well as solvents, formic and acetic acid, acetic anhydride, wet chlorine gas, hypochlorite, and chlorine solutions. This is what makes it so well used in the chemical processing industry. Finally, it also has excellent resistance to seawater corrosion, especially in crevice conditions.

2. Alloy C276 industry applications

With such a wide range of resistance, it is no wonder that INCONEL alloy C-276 is used in many industrial applications.

For example, it is used in flue gas desulfurization (FGD) systems to control air pollution in power plants. Components it is used in include scrubbers, piping, and stack liners. Compared to other alloys, INCONEL C-276 alloy has the ability to withstand higher chloride content before localized corrosion occurs. Given the presence of chlorides in scrubber liquids and gas condensates, this is certainly the preferred choice in this industry.

This nickel alloy has also been chosen for certain oilfield and subsea applications. When recovering and processing sour natural gas, which often contains hydrogen sulfide, carbon dioxide, and chlorides, the material needs to have good resistance to sulfide stress cracking and stress corrosion cracking. INCONEL alloy C-276 has high levels of nickel, chromium, and molybdenum, which together can provide this resistance even at high temperatures in deep wells. It’s used in things like piping, downhole, and surface components.

Its composition is also used for pollution control and waste treatment in very harsh environments. The high molybdenum content of INCONEL alloy C-276 helps create resistance to pitting and crevice corrosion. It is used in the most aggressive portions of waste liquid handling systems where other materials will not be able to cope with harsh conditions. In air pollution control, the alloy is used in stack linings, ducts, dampers, scrubber towers, stack gas reheaters, fans, and fan shrouds.

INCONEL alloy C-276 is also an important material in chemical processing. It has been selected for use in processes containing ferric and copper chloride ions, chlorine, hypochlorite, chlorine dioxide, organic acids, acetic anhydride, seawater, brine, and acidic oil and gas wellhead fluids. It is used in heat exchangers, reaction vessels, evaporators, and transportation piping.

Titanium is an important structural metal developed in the 1950s, and titanium alloys are widely used in various fields because of their high strength, good corrosion resistance, and high heat resistance. Many countries in the world have recognized the importance of titanium alloy materials, research, and development of its successive and practical applications.

In the 1950s to 1960s, the main development of high-temperature titanium alloys for aircraft engines and structural titanium alloys for airframes, the 1970s to develop a number of corrosion-resistant titanium alloys, and since the 1980s, corrosion-resistant titanium alloys and high-strength titanium alloys have been further developed. Titanium alloys are mainly used to make aircraft engine compressor components, followed by structural parts for rockets, missiles, and high-speed aircraft.

Titanium is an isomer with a melting point of 1668°C. Below 882°C, it has a dense hexagonal lattice structure, called α-titanium; above 882°C, it has a body-centered cubic lattice structure, called β-titanium. Using the above two structural characteristics of titanium, add the appropriate alloying elements so that its phase change temperature and phase content gradually change and get different organizations of titanium alloys (titanium alloys). At room temperature, titanium alloys have three kinds of matrix organization, and titanium alloys are divided into the following three categories: α alloy, (α + β) alloy, and β alloy. In China, they are expressed as TA, TC, and TB respectively.

Alpha titanium alloy is a single-phase alloy composed of α-phase solid solution, whether at general temperature or at higher actual application temperature, it is α-phase, with stable organization, higher wear resistance than pure titanium, and strong oxidation resistance. In the temperature of 500 ~ 600 ℃, it still, maintains its strength and creep resistance, but can not be heat treated to strengthen, room temperature strength is not high.

β titanium alloy is a single-phase alloy composed of β-phase solid solution, titanium alloy without heat treatment has high strength, and quenching, the aging alloy is further strengthened, with room temperature strength up to 1372 ~ 1666 MPa; but the thermal stability is poor, not suitable for use at high temperatures.

α + β titanium alloy is a duplex alloy with good overall performance, good organizational stability, good toughness, plasticity, and high-temperature deformation properties, can be better for hot pressure processing, quenching, and aging to strengthen the alloy. The strength after heat treatment is about 50% to 100% higher than the annealed state; high-temperature strength, can work at a temperature of 400 ~ 500 ℃ for a long time, and its thermal stability is second to alpha titanium alloy.

The most common of the three titanium alloys is α titanium alloy and α + β titanium alloy; α titanium alloy has the best machinability, α + β titanium alloy is the second, β titanium alloy is the worst. α titanium alloy code TA, β titanium alloy code TB, α + β titanium alloy code TC.

Titanium alloys can be divided into heat-resistant alloys, high-strength alloys, corrosion-resistant alloys (titanium-molybdenum, titanium-palladium alloys, etc.), low-temperature alloys, and special functional alloys (titanium-iron hydrogen storage materials and titanium-nickel memory alloys). The composition and properties of typical alloys are shown in the table.

Heat-treated titanium alloys can have different phase compositions and organizations by adjusting the heat treatment process. It is generally believed that the fine equiaxial organization has better plasticity, thermal stability, and fatigue strength; the needle-like organization has higher endurance strength, creep strength, and fracture toughness; the mixed equiaxial and needle-like organization has better overall performance.

Titanium alloys have high strength and low density, good mechanical properties, good toughness, and corrosion resistance. In addition, the titanium alloy process performance is poor, and cutting and machining difficulties, in hot processing, very easy to absorb impurities such as hydrogen, oxygen, nitrogen, and carbon. There are also poor anti-wear properties, the production process is complex. The industrial production of titanium was started in 1948. The need for the development of the aviation industry, the titanium industry to an average annual growth rate of about 8%. The annual output of titanium alloy processing material in the world has reached more than 40,000 tons, and there are nearly 30 kinds of titanium alloy de grades. The most widely used titanium alloys are Ti-6Al-4V (TC4), Ti-5) Al-2.5Sn (TA7) and industrial pure titanium (TA1, TA2 and TA3).