The corrosion resistance of the stamping elbow

Stamping elbow has certain corrosion (oxidizing acid, organic acids, cavitation), heat-resisting and wear-resisting performance. Usually used in power plant, chemical, oil and other equipment. Stamping elbow poor weldability, welding, heat treatment conditions should be paid attention to and choose suitable welding electrode.
The corrosion resistance of the stamping elbow depends on the alloy element content in the steel. Chromium stainless steel stamping elbow is get the corrosion resistance of the basic elements, while about 1.2% chromium content in steel, chromium and oxygen in erosion media effect, in the steel surface to form a thin layer of oxide film (since the passivation film), but to prevent further erosion of steel substrate. Elbow pipes with different production technology and processes, according to certain conditions is needed in processing production and processing, the different nature of the elbow pipe fittings some matters need attention in the process. For alloy elbow, if do alloy long radius elbow, must first to the selected of the specifications of the steel tube, pipe material, selection of quality steel pipe production. Alloy elbow has certain hole enlargement ratio, through theoretical calculation, the general hole enlargement rate is between 33% and 35%, push back. Short radius of 219 mm hole enlargement rate was 50%. Choose good raw materials, according to the alloy elbow materials specifications, then consider the radius of curvature, for example, the 90 ° elbow, through its curvature can calculate how much material can work out the 90 ° elbow. Through the theoretical calculation can be calculated, then based on the length scale. The final push materials for thermal system. Because of some elbow after improper handling, will be distorted, this is not allowed.

Stamping elbow won’t produce corrosion, pitting, corrosion or wear and tear. Stainless steel is used in metal materials in one of the highest material strength. Because stainless steel has good corrosion resistance, so it can make structure parts permanently maintain the integrity of engineering design. Chromium stainless steel stamping elbow also has high mechanical strength and extensibility, easy processing and manufacturing of parts, can be satisfied with the architect and structural design staff needs. All metal and atmospheric oxygen in the reaction, formed in the surface oxide film. Unfortunately, in the ordinary carbon steel oxidation of iron oxide is formed on the inheritance, kept expanding rust, ultimate forming holes. Can use paint or resistant to oxidation of the metal (for example, zinc, chromium and nickel) on plating to ensure that the surface of carbon steel, but, as we know, the protection is only a thin film. In addition, after have a haircut is usually large front end diameter, through plastic mould for plastic. The whole model is actually a press, want to have a set of mould, two and a half arc, the upper one. After the plastic outer diameter to reach the size of the finished product. Wall thickness in the wall thickness of incoming material control. Elbow and pipe wall thickness tolerance is the same, are the plus or minus 12.5%. Commonly used alloying elements except chromium and nickel, molybdenum, titanium, niobium, copper, nitrogen, etc, in order to content with various USES of stainless steel stamping elbow organization, and functional requirements.

Stamping elbow making matters needing attention when using electrode should be kept dry, titanium calcium type should be 1 hour after 150 ℃ drying, low hydrogen type should be 1 hour after the 200-250 ℃ drying (not sticky oil and other dirt, lest cause weld increased carbon content and influence the welding quality and mechanical properties. Sclerosing after welding is bigger, easy to crack. If using the same type of electrode welding, must be above 300 ℃ preheat and 700 ℃ or so slow cooling after welding. If it’s unable to weld heat treatment after welding, should choose chromium nickel stainless steel electrode.

In order to improve the stamping elbow corrosion resistance stability element Ti, Nb and Mo, weldability is better, using the same type of chromium stainless steel electrode, should be above 200 ℃ preheat and around 800 ℃ tempering treatment after welding. If cannot undertake the weldment heat treatment, should choose chromium nickel stainless steel electrode.

Source: Yaang Pipe Industry Co., Limited (www.yaang.com)

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