Welding for625 Nickel Alloy
2020-10-28
Welding for 625 Nickel Alloy
Nickel alloys have excellent corrosion resistance,Good ductility and high strength,It also has excellent comprehensive performance,It can be cold and hot deformation, smelting, casting and welding,It is widely used in aerospace, nuclear power station, offshore and platforms, oil and gas industry.
Welding on the water-wall
（using Gintune’s product GMN-CM3）
1、Characteristics of 625 alloy
Inconel 625 (UNS n06625) is a widely used nickel base alloy with Ni Cr Mo Nb as the main additive element. Its comprehensive properties are excellent,The characteristics are as follows:
● High temperature resistance: The higher content of Cr and Mo makes it have better resistance to high temperature peeling and oxidation;
● Low temperature resistance: Because of the high content of Ni, it still has good low temperature toughness at -196 ℃;
● High strength: Due to the diversity types and contents of alloy added, the composite strengthening of multi elements makes it with high strength, the tensile strength is above 760mpa;
● Corrosion resistance: 625 alloy shows excellent corrosion resistance in many media;
⑴. It has excellent resistance to pitting corrosion, crevice corrosion, intergranular corrosion and erosion in chloride medium;
⑵. It has good resistance to inorganic acid corrosion, such as nitric acid, phosphoric acid, sulfuric acid, hydrochloric acid, etc. at the same time, it also has the corrosion resistance of alkali and organic acid in oxidation and reduction environment;
⑶. Resistance to chloride ion corrosion and stress corrosion cracking;
⑷. The content of Mo is high, so it hardly corrodes in ocean and industrial gas environment;
⑸. NB, as a stabilized alloy, can reduce the susceptibility to intergranular corrosion.
2、Typical applications
Pressure equipment
Nuclear power equipment, nuclear reactor components, boiler piping system, heat exchanger, heat shield, valve, etc;
Gas desulfurization system
Desulfurization tower, absorption tower, reheater, flue gas inlet baffle, fan (wet) and flue gas, etc;
Chemical equipment
Manufacturing equipment and components for sour gas service, such as sulfuric acid condenser, acetic acid reactor, etc;
Aerospace Industry
Engine parts, aircraft engines, aerospace structural components, etc
Paper industry
Used to make pulping, digester and bleaching tank in paper industry
Marine engineering
It is used in the case of contacting with sea water and bearing high mechanical stress, structures in the sea, salt water environment, especially when acid chloride catalyst is used.
Flange welding
（using Gintune’s product GMN-CM3）
3、Welding materials and typical properties
4、Precautions
⑴. The cleaning of weld bead is the key, because the nickel content in the weld bead is high, the Ni is easy to form low melting point eutectic with P, s, Si and Pb, under the welding stress, it is easy to cause hot cracks.Therefore, the cleaning of the dust on the surface of work-piece and welding wire should be thoroughly removed before welding, wipe with alcohol or acetone if necessary; the groove shall be planed mechanically and the root cleaning can be done by sand grinding.
⑵. Using small welding parameters, for avoiding the coarse grain should control the heat input under 1.5KJ/mm, the interpass temperature should be under 100℃recommended ≤80℃), try to use small diameter welding wire, small welding parameters and rapid welding,prevent grain growth in weld bead and HAZ, this could cause decreases of the toughness of welded joint.
⑶. Choosing steels with low content of C、P、S、Fe, to prevent hot cracks and degradation of corrosion resistance.
<< return
prev：Introduction Auto Welding pipe...
next：Introducing gasless flux-cored...