The application range of cable ties: widely used in industry, agriculture, communications, petroleum, aviation, transportation, shipbuilding industry, etc. Under the action of corrosive medium, the stainless steel of cable tie is a kind of corrosion phenomenon called intergranular corrosion. The cable ties that cause intergranular corrosion will break along the grain boundary when the stress is applied, and the strength will almost completely disappear. This is one of the most dangerous forms of stainless steel damage. Intergranular corrosion can be generated in the heat-affected zone, weld or fusion line of the welded joint, respectively. The intergranular corrosion generated on the fusion line is also called knife-like corrosion.
Cable ties have corrosion resistance, and cable ties also have corrosion resistance. The necessary condition is that the mass fraction of chromium must be greater than 12%. When the temperature increases, the diffusion rate of carbon inside the cable tie grains is greater than that of chromium. Because the melting degree of carbon in austenite is very small at room temperature, about 0.02% ~ 0.03%, and the carbon content in general austenitic stainless steel exceeds this value, so the excess carbon will continue to austenite The grain boundaries diffuse and combine with chromium to form chromium carbide compounds between the grains, such as (CrFe) 23C8, etc. However, due to the slow diffusion rate of chromium, it is too late to diffuse to the grain boundary. Therefore, the chromium required for the chromium carbide formed between the grains is not mainly from the inside of the austenite grains, but comes from the vicinity of the grain boundaries. As a result, the grain boundaries The nearby chromium content is greatly reduced. When the mass fraction of chromium in the grain boundary is less than 12%, a so-called "chromium-depleted zone" is formed. Under the action of a corrosive medium, the chromium-depleted zone loses its corrosion resistance. And intergranular corrosion occurs.
