GRADE STAINLESS STEEL

 

SERIES 200

This chrome-manganese-nickel austenitic steels, with properties similar to AISI 301. In the annealed condition they remain fully austenitic structure. After cold deformation and the hardening of steel applicable in cases where the load must be considered in the construction factors. The combination of high contents of manganese and nitrogen as well as sufficient nickel kollichestva this alloy imparts excellent strength, toughness at cryogenic temperatures, and ambient temperature. Steel 200 series possess good oxidation resistance comparable with AISI 301 at temperatures up to 800 ° C Application Steel 200 Series are applicable in many fields, which traditionally used steel grade AISI 301 and 304. The alloys in this series are relatively cost-effective for compared with AISI 301 and 304 and thus have similar formability and weldability, and moderate good resistance to aggressive media. These steels can be welded by all conventional methods primenyamye to 304th stamp austenitic stainless steel. You can use a filler wire or electrodes of a conventional chromium-nickel steel 300 series. The sensitivity of these steels to intergranular corrosion in the heating zone when welding is similar to AISI 304. Steel brand 200 series very strong and plastic that can be easily cold drawn, bending, stretching and twisting.

 

Grade AISI 201 and AISI 202

This steel is a relatively inexpensive replacement for chromium-nickel austenitic steels 321 (08X18H10T), 304 (08H18N10) and others. Optimally alloyed with chromium, nickel, manganese, copper and nitrogen. Chemical composition provides an austenitic structure, high strength, excellent ability to deform. With the latest manufacturing techniques and a balanced chemical composition, austenitic steel grade 12H15G9ND has high corrosion resistance and does not concede on this indicator such popular brands like 08X18H10T, 08H18N10 et al. When used in the organic acid and other moderately corrosive environments. The steel is not suitable for the manufacture of containers and vessels for storage and transportation of acids and other highly aggressive chemical products. For a variety of mechanical properties of these steels are superior to steel grades 08X18H10T, 08H18N10 and others. Steel is easily plastically deformed, amenable to deep drawing and welding, using the same equipment as the standard chromium-nickel austenitic grades. On stamp are sanitary-epidemiological conclusions on the possibility of applications in the food industry. Technological properties: • Hot working: easily forged (at T ≥1260 ° C) and landing. Forgings may be cooled in air. • Cold working: easily handled in a cold state. Extremely durable plastic and with deep drawing, bending, punching and landing. Deformation hardening cold work steels like type 08X18H10T. • Machining: machining is performed under conditions that are similar to those for 08X18H10T type steels. It takes a few large processing force (e.g., cutting) steel as 201 and 202 have a higher strength. • Weldability: Easily welded using arc welding with protective atmosphere. It is possible to use nickel-chromium austenitic filler materials based on steel type 308 and others. High-temperature oxidation: The temperature of the beginning of intensive scaling is 760 ° C in continuous operation. Discoloration on the surface were observed in the temperature range 500-760 ° C by direct heating. In the case where the inside of the test vessel containing water, the surface is no change was observed during six hours of heating to reflux. Some applications: Food and household kitchen accessories: As a relatively inexpensive substitutes for stainless steel sheet 304 (08H18N10), these have become well established themselves abroad as a material for the manufacture of metal utensils, household kitchen utensils (dishes shallow, medium and deep-draw ratio; kitchen and cutting tables, water tanks, knives for cutting the products, etc .; and thermos flasks, water storage tanks, etc.), as well as for the manufacture of structural elements and apparatus for the food industry. Corrosion resistance of some "food" environments: Corrosion when fully immersed in a 3% NaCl solution Tests at room temperature for 720 hours in a boiling solution for 100 hours showed no visible signs of corrosion. The corrosion rate was very low, regardless of the test temperature, and was about 0.01 mm / year. Corrosion when fully immersed in different mixtures of organic acids (0.5% + 0.5% acetic breast); (0.5% + 0.5% citric wine). Tests at room temperature for 720 hours in boiling solutions for 100 hours showed no visible signs of corrosion. The corrosion rate was very low, regardless of the test temperature, and was about 0.01 mm / year. Addition to a mixture of 3% NaCI solution did not increase the corrosion rate. Crack under load: Test for 30 days at room temperature and for 100 hours in boiling above showed no cracking environments with increasing 500X. . Durables (including home use): Gas and other plates; drum washing machines, steel furniture (handles, locks, hinges for hinged doors, etc.), vases for flowers and fruit; trays etc. Architectural and engineering structures: window and door frames, railings and handrails; decorative designs and pipes; bins, trash cans and containers for waste, etc. Transport: caps on the wheels; Car decoration elements; Brush holders for cleaning glasses; rims and bumpers; Auto accessories etc.

SERIES 300

This chrome-nickel austenitic steels. This element stabilizes the austenitic nickel phase. Stainless steels, such as AISI 321 or AISI 304, AISI 316, etc., refer to the austenitic class. The presence of nickel in an amount of 8.10% leads to the fact that austenite phase is maintained at from reduced to 1050 ° C. The main advantage of austenitic steels is their high service characteristics (strength, plasticity, corrosion resistance in most operating environments) and good processability . Therefore, austenitic corrosion resistant steels are widely used as a structural material in various branches of engineering. This class includes steel 300 series. Application: Chemical industry. Virtually all containers, vessels, reactors, pipes and other equipment of the chemical industry made of austenitic stainless steels. The minimum acceptable mark is 1.4404 (AISI 316L); often require high-alloyed with molybdenum content of up to 6%. Food industry. Today, stainless steel with glass and some types of plastics is virtually the only material that is approved as a raw material for the manufacture of equipment for the production, storage and transportation of food. This is due to high demands on hygiene, toxicity, and others. Hygiene is of the utmost importance in the food industry. It largely determines the quality of the product all the way from the raw material through the manufacturing process to the consumer. Typically, 1.4301 (AISI 304) stainless steel grades are used for the production of food processing equipment and 1.4401 (AISI 316); in very rare cases may require high-alloyed. An important factor is good and smooth (no kinks, bumps and scratches) metal surface. Standard view 2B finish is sufficient, but sometimes need polishing (electrolytic). Roughness (Ra) surface is typically less than 0.6 microns. Pulp and paper industry. Almost all the equipment pulp mills and most of the paper are made from stainless steel. The minimum acceptable mark is 1.4401 (AISI 316). Electrical power. In this industry, as well as in nuclear power used stainless steel, and the last are always subject to special, high-alloy steels, since the requirements for materials used here are extremely high. Environment protection. Environmental protection is an important area of activity, the modernization of factories and workshops given preference for stainless steel because of the strength, durability, ecological compatibility and safety of this material. Use a wide range of brands, from an ordinary 1.4301 (AISI 304) up to high special steels. Transport. For the safety of the transport of various materials and liquids used special shipping containers and stainless steel tanks, as this material is easily cleaned and disinfected. For their manufacturing high-alloy steels are used, usually 1.4401 (AISI 316) or the like. In the automotive industry is most stainless steel is used to produce exhaust pipes and catalysts for the manufacture of which are ferritic or austenitic grades. Home life. Stainless steel - the ideal material for the manufacture of spoons, forks, frying pans, pots and other kitchen utensils, including internal parts high-quality dishwashers and washing machines and grinders of high quality. Construction and architecture. Stainless steel is well combined with glass, stone, wood and other materials that offer many interesting opportunities for facades and interiors, roofs of public buildings. Stainless steel is also used for the manufacture of outdoor furniture, office and home interior items, railings and staircases. In addition, there are a surprising number of color and decorative (embossed, corrugated) surfaces, which differ remarkably long line service, and the colors do not fade over time.

SERIES 400

Grade AISI 430

AISI 430 - the most widely used ferritic chromium corrosion-resistant steel of general purpose (in accordance with standard ASTM A240), which combines:
• high strength and mechanical properties;
• high corrosion resistance, including atmospheric, provides a high chromium content and low carbon content;
• workability (good plastic deformability, the applicability to the drawing processes, stamping, punching holes in it, etc.)
Steel AISI 430 is widely used in the following industries:
• civil engineering;
• architecture and design;
• food industry;
• manufacture of kitchen utensils, tables, a serving tool, wash basins, sinks, washing machines parts, drums and pallets for dishwashers, etc .;
• automotive (decorative exhaust system, etc.);
• production of external and internal fittings;
• equipment for heat exchangers;
• other.
In accordance with literature data multiple reference ferritic steel AISI type 430 can be used for manufacture of machine parts and apparatus for the wine industry. These steels are allowed to be used in direct contact with the wort, wine, brandy spirits, wine products processing waste, etc. Allowed to use these steels (08H17T) for the manufacture of equipment used in the meat and dairy industry at a temperature of 30-140 ° C, etc. Steel AISI 430 can be used for the production of technological equipment used in various stages of food production (washing or hygienic handling of raw materials, products and equipment, shredding, separation and sorting of products, mixing, cooking, packaging and packaging, transportation, etc. ). Steel series AISI 400 (including 430 and steel) can not only be used as substitutes for nickel stamps, but also, in a number exceeding the last properties are often indispensable for the manufacture of food processing equipment. Steel AISI 430 corresponds to the state sanitary-epidemiological rules and norms and is very promising for use in the manufacture of equipment for various sectors of the food processing industry: oil and fat, meat, bakery, beer and soft drinks, alcohol, alcoholic beverage, confectionery and others. Products made of this steel can be used on such technological stages of food production as a washing or hygienic handling of raw materials, products and equipment; shredding, separation and sorting of products; mixing, heat treatment, packing, packaging and transportation. High corrosion resistance is AISI 430 grade wire, due to the reduced carbon content in combination with high chromium content (16-18%). As compared with the nickel-containing austenitic steels, chromium steels have a low coefficient of thermal expansion (CTE) and high thermal conductivity, which determines their preferential use (including rolled tube) in such structures as the cooling heat exchange gradilni etc. Low CTE provides more reliable fastening the Fitting provides accelerated heat transfer and cooling systems in food reservoirs (glycol cooling system, cooling water and other fluids). Welded structures and pipelines from chromium steels substantially less resize with temperature fluctuations, which determines the reduction of destructive fatigue loads during temperature changes and prevent possible leakage of the hydraulic connections. Steel AISI 430 has proven itself as a sustainable material in gases resulting from the combustion of various fuels. These media may contain a full (carbon dioxide, water vapor, nitrogen, etc.) and the partial products (carbon monoxide, hydrocarbons, nitrogen oxides, sulfur dioxide, hydrogen sulfide, etc.) combustion. It is used for the manufacture of shells and tubes neutralization systems, recycling, collecting and exhaust emissions. Complex redox catalytic reaction and high temperature corrosive gas environments dictate the use of economically indispensable AISI 430 stainless steel as a structural material for the manufacture of exhaust systems, and also for the furnace and associated equipment (exhaust ducts, chimneys etc.) Welding: This steel is perfectly welded by any known means. Provided taken if post weld dressing operation / passivating and cleaning will not occur in the loss of the corrosion properties of the weld (including the heat affected zone). Optimal use of arc welding in inert gases in compliance with minimum energy input in the weld seam. Recommended welding "on top" (ie, when the welded surface is located below the welding tool). As the filler material can be used austenitic wire 309L, Savanoriu Str-07Kh25N13, St-08H25N13BTYU etc. You can use electrodes or filler wires on the basis of chromium ferritic steel AISI 430. In order to ensure adequate corrosion resistance is necessary to remove scale and discoloration by etching or machining of stainless steel brushes and propassivirovat 10-20% cold solution of nitric acid. Necessary followed by thorough washing with cold water and drying.

 

Grade AISI 410

AISI 410 - a base martensitic stainless steel, hardened by heat treatment and which has high durability. This steel has good ductility, high toughness, good corrosion resistance and heat resistance. In the annealed (softened) state delivery of steel structure is a mixture of ferrite and carbide phase. When heated to a temperature of 960-1020 ° C and subsequent quenching (air or oil) is formed martensite, the hardness of which is directly proportional to the carbon content. The resulting chromium carbides dispersed further strengthens the structure of the steel, increasing its hardness and wear resistance. Applications steel AISI 410: It is used in cases where the necessary combination of high wear resistance and good corrosion resistance. Namely: • Cutting tools (knives, scissors, etc.); • parts of turbines and boilers; • fasteners, wear-resistant lining; • thermal and separation screens, filters; • kitchenware; • other. In accordance with literature data multiple reference AISI 410 type martensitic steel can be used for manufacture of machine parts and devices are in direct contact with food. Steels such as AISI 410 (12H13) can be used for the manufacture of machine parts and machines for the wine industry. These steels are allowed to be used in direct contact with the wort, wine, brandy spirits, wine products processing waste, etc. Steel AISI 410 can be used for the manufacture of technological equipment used in various stages of food production (washing or hygienic handling of raw materials, products and equipment, shredding, separation and sorting of products, mixing, cooking, packaging and packaging, transportation, etc. ) * Tempering by heating to 980 ° C, followed by cooling in air and tempering at 200 - 555 ° C Properties at elevated temperatures: AISI 410 steel has good resistance to the formation of scale up to 700 ° C

 

Grade AISI 409

AISI 409 - titanium stabilized ferritic chromium corrosion-resistant steel of general purpose (in accordance with standard ASTM A240), which combines:
• high strength and mechanical properties;
• corrosion resistance, including atmospheric;
• workability (good plastic deformability, the applicability to the drawing processes, stamping, punching holes in it, etc.).
• actually contains minute quantities of carbon (<0.03%).
Areas of industrial use steel AISI 409:
• Сivil engineering;
• Architecture and design;
• Food industry;
• Automobile industry (exhaust system, etc.);
• Production of containers;
• Chemical and petrochemical production (substitute steel 08H13);
• Paper industry (pulp grinding);
• Processing and household sewage, etc.
• Mining (and everything connected with it, including Shaft design, etc.)
• Other.
The stabilized titanium heat-resistant corrosion-resistant steel grade AISI 409 is the improved analogue of steel 08H13. It contains minute quantities of carbon (0.03%), well-welded, not prone to intercrystalline corrosion and, having improved properties as compared with steel 08H13, it can be successfully replaced in the following applications: parts with high ductility undergoing shock (hydraulic valves presses, household items), as well as the products are exposed to slightly aggressive media (precipitation, aqueous solutions of salts of organic acids at room temperature, and others.), blades of steam turbines, valves, bolts and pipes .. Steel AISI 409 can be used for the production of technological equipment used in various stages of food production (washing or hygienic handling of raw materials, products and equipment, shredding, separation and sorting of products, mixing, cooking, packaging and packaging, transportation, etc. ). Steel series AISI 400 (including 409 and steel) can not only be used as substitutes for nickel stamps, but also, in a number exceeding the last properties are often indispensable for the manufacture of food processing equipment. For example, compared with the nickel-containing austenitic steels, chromium steels have a low coefficient of thermal expansion (CTE) and high thermal conductivity (see Table 3), which determines their preferential use (including tube rolling) in such heat exchange structures like cooling gradilni etc. P. Low CTE provides more reliable fastening the Fitting provides accelerated heat transfer and cooling systems in food reservoirs (glycol cooling system, cooling water and other fluids). Welded structures and pipelines from chromium steels substantially less resize with temperature fluctuations, which determines the reduction of destructive fatigue loads during temperature changes and prevent possible leakage of the hydraulic connections. Steel AISI 409 has proven itself as a sustainable material in gases resulting from the combustion of various fuels. These media may contain a full (carbon dioxide, water vapor, nitrogen, etc.) and the partial products (carbon monoxide, hydrocarbons, nitrogen oxides, sulfur dioxide, hydrogen sulfide, etc.) combustion. It is used for the manufacture of shells and tubes neutralization systems, recycling, collecting and exhaust emissions. Complex redox high temperature catalytic reactions and corrosive gas environments dictate the use of economically indispensable stainless steel AISI 409 as a structural material for the manufacture of exhaust systems, as well as furnace and related equipment (exhaust ducts, chimneys, etc.). Properties at elevated temperatures: Steel AISI 409 is not hardened by heat treatment and has good resistance to the formation of the scale up to 7000 C, preserving its useful operating the mechanical properties at high temperatures. This steel has good oxidation resistance at relatively high temperatures and maintains high performance in conditions where the carbon and manganese steel can not be used. Steel 409 is classified as zharoostoykaya with intermittent operation to 815 ° C and in continuous operation up to 700 ° C. However, the actual operating temperatures depend on the operating environment. Steel AISI 409 is used only in neutral and oxidative environments it can not be used in a reducing environment. Up to 500 ° C is observed creep pronounced, but quickly degraded mechanical properties over a given temperature. At temperatures above 500 ° C and heat resisting steels to be used in the presence of heavy loads. Steel AISI 409 is a ferromagnet (magnet). Processing and some technological properties of steel AISI 409: cutting: The most effective way is cutting guillotine or abrasive using a specially designed besprizhogovyh drives based on SiO2 or Al2O3, as well as oxygen-free nitrogen plasma cutting. Plastic deformation: Technical higher tensile strength and assumes higher deformation force as compared to carbon steels. When bending of the steel it is important to maintain a minimum inside bend radius equal to two thicknesses of material. The subsequent bend in the opposite direction is not recommended - bending area in this case needs to be heated to 150 ° C. It is possible to avoid occurrence of edge cracks if bent metal cutting, it is not cut from the internal radius and external. This type of cracking can be eliminated if podshlifovat outer radius, and thus remove the stress concentrator. Welding: This steel is perfectly welded by any known means. Provided taken if post weld dressing operation / passivating and cleaning will not occur in the loss of the corrosion properties of the weld (including the heat affected zone). Optimal use of arc welding in inert gases in compliance with minimum energy input in the weld seam. Recommended welding "on top" (ie, when the welded surface is located below the welding tool). As the filler material can be used austenitic wire 309L, Savanoriu Str-07Kh25N13, St-08H25N13BTYU etc. In order to ensure adequate corrosion resistance is necessary to remove scale and discoloration by etching or machining of stainless steel brushes and propassivirovat 10-20% cold solution of nitric acid. Necessary followed by thorough washing with cold water and drying. Machining: Reduced deformation hardening compared to austenitic steels, suggests a requirement of special tools. Low processing speed and a small cutter feed, a sufficient amount of coolant, eliminate any problems when machining steel. Fasteners, joints: If bolted design will be used in a humid atmosphere, it is strongly recommended to use water resistant gaskets (eg, rubber).

TIPS IN WORKING WITH STAINLESS STEEL

As polished stainless steel (stainless pipe, sheet):

Smooth mirror surface stainless pipe and sheet can be obtained not only in the factory, polishing stainless steel is quite possible and at home. This process is necessary to give a spectacular kind of homemade paper, sweep welding seams or to neutralize the surface scratches. To do this you will need:

• angle grinder (Bulgarian);

• grinding wheels of different grits;

• sandpaper or stone;

• felt or felted circles;

• polishing paste.

Please make a rough cleaning of the surface, remove weld spatter from the weld. To do this, use the circle on the basis of fiber. If the surface is smooth enough, skip this step. In order to remove the risk of grain take a felt or felt circle and uniformly apply it carpenter's glue. Then gently walk them on the abrasive crumbs. The abrasive chips may be obtained from the emery cloth or a stone, rubbing them against each other. Sand the surface of stainless steel a few times, each time reducing the size of abrasive twice. Do not forget to wash the surface of the stainless steel after each grinding. Check the surface after grinding must be perfectly smooth. Make sure that eliminated all coarse roughness, or after polishing these areas will have to grind again. Take a clean felt or felted circle and polishing paste. It is important to choose the right polishing paste, as for various brands of stainless steel suitable for different kinds of pasta. Try to find a diamond paste, which corresponds to grit your metal, at most, a common approach or polishing paste GOI. Start finish polishing stainless steel, consistently removing visible risks. Gradually, over time, you will see that the surface becomes more smooth, this is due to the fact that under the influence of high temperature parts surface melts and spreads. Be careful not to overheat the detail of some of the metals that can change color.

 

How to identify stainless steel:

Stainless steel, has the qualities that are specific to this type of steel. To distinguish it from the "brothers" can be, subjected to some tests. You can do this by placing steel in a salt solution. You can resort to more sophisticated methods, using physical calculations. To do this you will need: • - salt; • - water; Since, on the basis of the name, "stainless steel" is resistant to rust, you should check it at this point. It is necessary to make a concentrated solution of salt in water and put it in a stainless steel product. The following day, the result can be evaluated. Stainless steel can be food and non-food. You can distinguish them by using a spectrographа.

 

How to cook a stainless steel:

Welding is a process of permanent connection of parts by setting between the interatomic bonds when heated or plastic deformation. Generally, welding is used to connect the various metals and their alloys. When welding stainless steel parts must take into account differences between the physical properties of "stainless steel" from the carbon steel properties. What are the ways of welding "stainless"? From carbon-rolled stainless steel is distinguished by a large resistivity, the lower the melting point and thermal conductivity, a greater percentage of thermal expansion. Perform welding stainless steel in several ways. With material thicknesses exceeding 1.5 mm is commonly used manual arc welding with tungsten electrode in inert gas. High performance is achieved when welding thin sheets of stainless steel as well as stainless steel tubes. But for welding sheets of "stainless steel" thickness of 0.8 - 1.5 mm is suitable welding pulse arc with consumable electrode in an inert gas and arc welding with the spray of metal. All the more widely used plasma welding. For thick stainless metal produced submerged arc welding, and for thinner sheets and roller spot welding. After welding, post-processing is required welds. On the surface of the compound obtained by welding, a porous oxide layer is formed, which substantially weakens the resistance of the weld with respect to corrosion. For further processing the various methods used welds. One such way of processing is considered welds etching. When used properly, can eliminate harmful etching the oxide layer and a zone with a reduced chromium content. Depending on the specific conditions of etching is performed by immersion, coating the surface of the coating or paste products. The most frequently used mixed acid in combination with water. etching time of stainless steel depends on the acid concentration, scale thickness, temperature and grade of stainless steel. Another processing step for welding "stainless steel" - the degree of finishing roughness of the weld to the corresponding index of the base material. And this is achieved by grinding and polishing after performing the etching. Such processing usually enhances the corrosion resistance of the construction.

 

How to weld stainless steel:

Stainless steel is one of the most popular among all types of steel. Advantages of stainless steel - a high corrosion resistance, surface smoothness, hygiene, durability, workability, practicality. For welding stainless steel, you will need certain skills to work with welding machines for this process went quickly, efficiently and without harm to anyone. Welded stainless steel using a welding machine and rectifier, but not simple, and the rectifier with choke. Neutral does not fit perfectly, because with them the process will become more complicated, and in sheer torture, so spare your nerves and take what you need. Also for welding stainless steel will need special electrodes desirable good quality, otherwise the entire process will be spoiled. It can be black and the electrodes, but in this case problems may arise with sutures. It is better to cook stainless steel argon. If this option is you do not have the equipment, then go to step 2. Weld in a heated state at a temperature of about 2000 ° C, being careful to ensure that the heating of stainless steel during welding was minimal. If you compare, the more acceptable result is obtained by an electric rather than gas welding. After the connection works produced heat to 7200-7800 ° C and then quickly cooled. If this option is you do not have the equipment, then go to step 3. Step 3: Cook stainless steel at high speed and very rapid cooling, which often can be achieved by applying cooling or copper lining and lining under the weld. Previously the product is subjected to "hardening» 1050-1150 ° C followed by flash cooling. If this option is you do not have the equipment, then go to step 4. Warm up before welding stainless steel up to 2500-3500 ° C. This will avoid cracking and breaking welds. The electrodes use austenitic steel, through which a viscous weld. Main follow all accurately, calm and measured, then the probability of errors and failures in welding will be minimal.Stainless steel is one of the most popular among all types of steel. Advantages of stainless steel - a high corrosion resistance, surface smoothness, hygiene, durability, workability, practicality. For welding stainless steel, you will need certain skills to work with welding machines for this process went quickly, efficiently and without harm to anyone. Welded stainless steel using a welding machine and rectifier, but not simple, and the rectifier with choke. Neutral does not fit perfectly, because with them the process will become more complicated, and in sheer torture, so spare your nerves and take what you need. Also for welding stainless steel will need special electrodes desirable good quality, otherwise the entire process will be spoiled. It can be black and the electrodes, but in this case problems may arise with sutures. It is better to cook stainless steel argon. If this option is you do not have the equipment, then go to step 2. Weld in a heated state at a temperature of about 2000 ° C, being careful to ensure that the heating of stainless steel during welding was minimal. If you compare, the more acceptable result is obtained by an electric rather than gas welding. After the connection works produced heat to 7200-7800 ° C and then quickly cooled. If this option is you do not have the equipment, then go to step 3. Step 3: Cook stainless steel at high speed and very rapid cooling, which often can be achieved by applying cooling or copper lining and lining under the weld. Previously the product is subjected to "hardening» 1050-1150 ° C followed by flash cooling. If this option is you do not have the equipment, then go to step 4. Warm up before welding stainless steel up to 2500-3500 ° C. This will avoid cracking and breaking welds. The electrodes use austenitic steel, through which a viscous weld. Main follow all accurately, calm and measured, then the probability of errors and failures in welding will be minimal.

STAINLESS STEEL RUST

Causes rust, how to avoid rust

Very often our employees to hear from customers wish to order for them has been used stainless steel pipe or sheet that will not rust. And sometimes request that was "not Chinese" stainless steel. What determines whether or not rust stainless steel, and why all this is happening? There may be several reasons. The first is the operating conditions of stainless steel in aggressive env ironments. The second - defects in the material. Consider these phenomena more: Pitting caused by chlorine-containing cleaning veschestvami. Not all types of stainless steel are designed for operation in harsh environments. For example in the food production used in industrial processes and chlorine-based cleaning agents there may be used stainless steel with high corrosion resistance. The same applies to the conditions of operation in seawater. For this reason, equipment, for example, AISI 304 may simply come into disrepair. For aggressive media makes sense to use AISI 316, or duplex stainless steels such as Ferralium SD40, SAF 2205 and Zeron 100. The second reason is more common - may rust on the metal surface as a consequence of mechanical damage or thermal treatment (caused by welding). This so-called pitting. This type of corrosion may begin where the metal impurities are present, such as for example sulfur. Smooth mirror surface stainless metal less susceptible to pitting corrosion than sherohovataya.Sledy rust can occur even in places where a red-hot cinder got. This is because at the welding burn alloying elements, especially chromium. On the metal in the welding points are formed, "traces of discolouration" (sometimes referred to as traces of thermal effects). In these places will inevitably begin to rust stainless steel. Rust layer, however, may be left only on the metal surface where no oxide film is formed due to chromium. That is, in the depths of rust will not develop. But looks like discolouration and even more so rust is not very aesthetically pleasing. To avoid this weld treated with special emulsions, pickling paste or use abrasives. When cleaning the seam of iron oxides (oxides of scale) pickling paste should work goggles, and apply only to the cooled metal as they may contain contain hydrofluoric acid. After purification, the weld area must be subjected to passivation operation. passivation - is the process of surface treatment with aim of education in her layers of compounds of preventing corrosion. That is, just enough to clear a weld welding products, it is also necessary to restore the protective layer. To do this, just as there are various chemicals: gels, pastes. Sometimes it is used for the passivation of stainless steel nitric or citric acid. Electro-chemical passivation nerzhaveki: there are innovative ways of cleaning and passivation. For example the method of electro-chemical passivation of stainless steel. Moreover, this process is carried out without the use of etching products, which are very harmful to health and the environment.