What is sus316 tig stainless steel pipe?

1. Core characteristics of SUS316 stainless steel pipe

Contains 2-3% molybdenum (Mo), compared with SUS304, the pitting and crevice corrosion resistance is increased by more than 50%, especially in chlorides (such as seawater, salt solution), sulfuric acid, acetic acid and other media.
Carbon content Less than or equal to 0.08%, adding a small amount of nickel (Ni 10-14%) and chromium (Cr 16-18%) to ensure good oxidation resistance and processing performance.

Tensile strength Greater than or equal to 520MPa, yield strength Greater than or equal to 205MPa, elongation Greater than or equal to 40%, suitable for structures requiring high strength and high toughness.
High temperature resistance is stable, can be used for a long time in the range of - 196 degree ~800 degree , and has strong creep resistance at high temperature.

Key points of SUS316 stainless steel pipe (TIG welding) process
The argon arc welding of SUS316 stainless steel pipe has become the preferred welding method due to its advantages such as stable arc, controllable heat input and beautiful weld formation.
1. Welding material matching
Wire selection: It is recommended to use ER316L (low carbon type, C Less than or equal to 0.03%) or ER316 welding wire to avoid intergranular corrosion caused by carbide precipitation in the weld. When the corrosion resistance requirement is extremely high (such as medical and food equipment), ER316L is preferred.
Shielding gas: pure argon (purity Greater than or equal to 99.99%) or argon + 2% nitrogen (increases penetration, suitable for thick-walled pipes), gas flow rate 8-15L/min, to ensure full protection of the molten pool.
2. Welding parameter control
Current and voltage: Adjust according to the pipe diameter and wall thickness, usually 80-150A current, 10-15V voltage, thin-walled pipe ( Less than or equal to 3mm) uses small current for fast welding to reduce the width of the heat affected zone (HAZ).
Welding speed: 5-15cm/min, too fast will easily lead to unfusion, too slow will increase the risk of grain coarsening and deformation.
Tungsten pole diameter: φ2.0-3.2mm, tip angle 60 degree -90 degree , to ensure arc concentration and stability.
3. Pre-welding and post-welding treatment

Preheating and cooling: Usually no preheating is required (unless the ambient temperature is below 0℃ or the thick-walled pipe is >10mm), cool naturally after welding to avoid forced water cooling causing stress concentration.
Post-weld treatment:
Pickling and passivation: Use nitric acid + hydrofluoric acid solution to remove weld oxide scale and restore surface corrosion resistance (applicable to chemical and marine equipment).
Radiographic testing (RT) or penetration testing (PT): For pipelines in high-pressure and high-corrosion scenarios, 100% flaw detection is required to ensure that there are no defects such as pores and slag inclusions.

Application of SUS316 stainless steel pipe


Advantages: Resistant to intergranular corrosion and stress corrosion cracking, and strong long-term service stability.