Main points of nickel tube welding process:

(1) correct choice of welding materials

(2) joint type: big groove Angle and small pure edge joint type

(3) cleaning near the groove and welding wire: features are important to prevent thermal cracks and pores.

(4) preheat before welding: preheat before welding is generally not needed, and the interlayer temperature should be controlled below 100 ℃. However, when the base material temperature is lower than 15℃, it should be heated to 15-20 ℃ to avoid condensation of moisture.

(5) welding process:

◇ limit the heat input, use small line amount and maintain the stability of arc voltage, and use the operation method of short arc no swing or small swing.

Forced cooling measures should be taken to reduce the high-temperature residence time of welding seams and increase the cooling speed of welding seams in the welding process of small diameter pipe.

Weld surface slag and spatter cleaning in time after welding, in order to prevent the slag S and other impurities on the weld brittleness or corrosion degradation.

(6) post-weld heat treatment: post-weld heat treatment is generally not recommended. However, heat treatment is sometimes required to ensure no intergranular corrosion or stress corrosion in use.

The welding material selection principle of nickel-based alloy:

(1) welding material selection for the same nickel material:

◇ use the same welding materials as the base metal alloy series

◆ if no corrosion resistance requirements, can also choose different from the base metal alloy system welding materials, but should ensure that the joint has the performance required by the design.

S, for instance:

Monel 400: electrode enicu-7; Wire ERNiCu - 7

Inconel600: electrode enicrfe-1; Wire ERNiCrFe - 5

Coloy 800H: electrode enicrfe-2; Wire ERNiCr - 3

Hastelloy c-276: electrode enicrmo-4; Wire ERNiCrMo - 4