321 Ti stainless steel which exist as a stabilizing element, but it is also heat resistant steels, high temperature is much better than the .321 316L stainless steel in different concentration and temperature of organic and inorganic acids, especially in oxidizing medium has good abrasion performance, for the manufacture of equipment wear and acid containers and wear lining pipes. 321 stainless steel is Ni-Cr-Ti-type austenitic stainless steel, its performance is very similar to the 304, but due to the addition of titanium, it has a better intergranular corrosion resistance and high temperature strength. The addition of titanium, making it effective control of the formation of chromium carbides. Excellent high temperature stress of 321 stainless steel with a breaking (Stress Rupture) properties and high temperature creep resistance (Creep Resistance) stress mechanical properties are superior to 304 stainless steel. Application Used in open field machinery, grain boundary corrosion resistance for high chemical, coal, oil industry, building materials, heat-resistant parts and heat treatment difficult parts, such as:... An oil pipeline two exhaust combustion engine exhaust pipe 3 boiler shell heat exchanger, furnace parts 4 diesel muffler section 5. Boiler and Pressure Vessel 6 chemical truck 7. Expansion joints 8. burning stove pipes and dryer with spiral welded 321 stainless steel size tolerances and tolerance deviations grade standardized outside diameter tolerance D1 ± 1.5%, minimum ± 0.75 mm D2 ± 1.0%. Minimum ± 0.50 mm D3 ± 0.75%. Minimum ± 0.30 mm D4 ± 0.50%. Minimum ± 0.10 mm stainless steel pipe weight formula: [(OD - Wall Thickness) * thickness] * 0.02491 = kg / m (weight per meter) 2 Physical properties Chemical composition Carbon C: ≤0.08 Si Si: ≤1.00 manganese (Mn) : ≤2.00 sulfur S: ≤0.030 phosphorus P: ≤0.035 chromium Cr: 17.00 ~ 19.00 Ni-Ni: 9.00 ~ 12.00 Titanium Ti: ≥5 × C% mechanical properties of tensile strength σb (MPa): ≥520 Conditions yield strength σ0. 2 (MPa): ≥205 Elongation δ5 (%): ≥40 section shrinkage ψ (%): ≥50 Hardness: ≤187HB; ≤90HRB; ≤200HV heat treatment and microstructure heat treatment specifications: 1) solid solution 920 ~ 1150 ℃ rapid cooling; 2) According to the requirements may be stabilizing treatment, heat treatment temperature is 850 ~ 930 ℃, but it must be specified in the contract. 3) The solution temperature should not exceed 1066 ℃, more than words, stabilizing treatment must be carried out to prevent precipitation of chromium. Microstructure: Organizing for the austenitic type. Delivery status: generally heat treatment delivery, the treatment types specified in the contract; not indicated, by not heat treatment delivery. 3 Knowledge stainless steel (Stainless Steel) refers to the resistance of air, steam, water and other corrosive medium and weak acid, alkali, salt and other chemical etching medium corrosion of steel, also known as acid-resistant stainless steel. Practical applications, often the weak corrosion resistance as stainless steel corrosion media, while the chemical resistance of steel known as acid corrosion of steel. As the two differences in the chemical composition, the former is not necessarily resistant to chemical corrosion, while the latter generally has a stainless steel sex. The corrosion resistance of stainless steel depends on the alloying elements contained. Types of stainless steel is often divided by organizational status: martensitic steels, ferritic steels, austenitic steel. In addition, according to the ingredients into: chrome stainless steel, chrome-nickel stainless steel and chrome manganese nitrogen stainless steel. 1, ferritic stainless steel: chromium 12% to 30%. Its corrosion resistance, toughness and weldability with the increase of chromium content increased resistance to chloride stress corrosion better than other types of stainless steel. Fall into this category have Crl7, Cr17Mo2Ti, Cr25, Cr25Mo3Ti, Cr28 and so on. Ferritic stainless steel because of high chromium content, corrosion and oxidation resistance are relatively good, but poor mechanical properties and process performance, and more for large discontinuity acid structure and antioxidant for steel. Such steel is resistant to corrosive atmosphere, nitric acid and saline solution, and has good oxidation resistance, thermal expansion coefficient, etc., for the nitric acid plant equipment and food, can also be produced parts at high temperatures, such as gas turbine parts, etc. . 2, austenitic stainless steel: more than 18% chromium, it also contains about 8% nickel and a small amount of molybdenum, titanium, nitrogen and other elements. Good overall performance, corrosion resistant variety of media. Common austenitic stainless steel grades are 1Cr18Ni9,0Cr19Ni9 like. 0Cr19Ni9 steel wC <0.08%, steel marked "0." This kind of steel contains large amounts of Ni and Cr, the steel at room temperature was austenitic state. Such steel has good ductility, toughness, weldability and corrosion resistance, corrosion resistance are good in oxidizing and reducing medium, used to produce acid and equipment, such as containers and equipment corrosion lining, pipelines, corrosion equipment parts, such as nitric acid. Austenitic stainless steels commonly used solution treatment, is about steel heated to 1050 ~ 1150 ℃, and then cooled to obtain a single-phase austenite. 3, austenitic - ferritic duplex stainless steel: the advantages of both austenitic and ferritic stainless steel, and has superplasticity. Austenitic and ferritic stainless steel accounts for about half of each organization. In the case of containing a lower C, Cr content of 18% ~ 28%, Ni content of 3% to 10%. Some steel further contains Mo, Cu, Si, Nb, Ti, N and other alloying elements. Both austenitic class steel and ferritic stainless steel features, higher compared with ferrite, ductility, toughness, brittle at room temperature, resistance to intergranular corrosion and welding performance are significantly improved, while also maintaining a ferritic stainless steel 475 ℃ brittle and high thermal conductivity, with superplastic characteristics. Compared with the austenitic stainless steel, high strength and resistance to intergranular corrosion and chloride stress corrosion has significantly improved. Duplex stainless steel has excellent resistance to pitting corrosion, but also a section of nickel stainless steel. 4, martensitic stainless steel: High strength, but poor ductility and weldability. Martensitic stainless steel grades are commonly 1Cr13,3Cr13 etc., due to higher carbon, it has a high strength, hardness and wear resistance, corrosion resistance, but somewhat less, the requirements for high mechanical properties, corrosion resistance General requirements on the part of some, such as springs, turbine blades, valves and other hydraulic press. Such steel is after quenching, tempering use.