If manufacturers need to improve the quality of pipelines, then intergranular corrosion is a problem to be overcome in the pipeline production process.
We will carefully discover an invisible type of corrosion damage called intergranular corrosion (IGC) to understand how intergranular corrosion occurs and how to detect and mitigate damage.
What is the intergranular corrosion？
In materials science, intergranular corrosion (IGC), also known as intergranular attack (IGA), is a form of corrosion where the boundaries of crystallites of the material are more susceptible to corrosion than their insides. Intergranular corrosion (also known as weld decay) affects stainless steel at the structural level and may not show visible signs of damage until corrosion has significantly progressed.
Why does intergranular corrosion occur？
In short, intergranular corrosion is triggered by welding of pipes, improper heat treatment, and exposure between 425 and 870 degrees Celsius.
When the metal in the temperature of this range, it changes at the structural level. The chromium present in the alloy reacts with carbon to produce chromium carbide near the grain boundary. This carbide formation essentially converts the boundary into an anode cells. Crystal particles inside the cathode cells, and corrosion start.
Methods to mitigate intergranular corrosion？
Thermal treatment can usually solve the problem, bringing the metal structure back to near the original state.
Annealing or quenching is an effective method to reversing corrosion damage in austenitic stainless steel.
This process heated the metal to between 1060℃ and 1120℃. Once heated, the stainless steel pipe is heated, quickly cooled to solidify the grain and structure. This annealing is usually used in high-standard industrial welded pipe production.
So how did we get there?
On-Line Fixing & Fusing (Anealing) equipment can heat the stainless steel welded pipeto 1050°C then cool it to the temperature lower than 100 °C under the protection of hydrogen.The heating power supply of the intermediate ferquency induction is the newest DSP+IGBT structure.With DSP digital control system,there are self protection and self diagnostic functions.With small volume,it heats pipes rapidly and efficiently with energy-saving and low-waste features.The especially developed inducer designed according to the features of stainless steel can save 15%-20% energy in contrast of other products of the same class.Using hydrongen as of gas every minute.
To learn more, pleasr click here: Electricity-Powered Stainless Steel Tubing Bright Annealing Furnace
