Writer: Eric Bearing Limited
Austenitic stainless steel
Corrosion resistance:Both have stainless and corrosion resistance. As the amount of Cr increases, resistance to oxidizing acid corrosion such as nitric acid and high temperature oxidation resistance, vulcanization performance improves. As the amount of Ni increases, the resistance to chloride stress corrosion and the resistance to reducing acids increase. As the amount of C decreases, or stabilizing elements are added, the intergranular corrosion resistance of steel is improved. As the amount of Mo increases, the steel's resistance to reducing acids and pitting corrosion and crevice corrosion performance increase. The steel contains Cu, especially Mo, Cu compound. The sulfuric acid resistance of the steel has been significantly improved. When it contains Si~4%, it can resist fuming nitric acid corrosion. Reduce the content of impurity elements C, Si, P, Ti in some steels, can be used as nitric acid grade and urea grade stainless steel.
Mechanical and physical properties:
All have a good combination of strong-toughness-plasticity, excellent low temperature toughness, and can be used as low temperature steel. As the amount of C in the steel decreases, the strength of the steel decreases slightly (generally low carbon steel is 29.4 to 49 MPa lower than the higher carbon). As the amount of cold deformation increases, the strength and elasticity of the steel increase. When the steel contains N, the strength of the steel increase. Due to the strengthening effect of Mn and N, Cr-Mn austenitic stainless steel is about 30% stronger than Cr-Ni austenitic steel, and its plasticity and toughness are still good. Most of these steels are non-magnetic, so they can be used as non-magnetic steel. INA GE 50 KRRB bearings online , pls click here :
Martensitic stainless steel
Martensitic chromium stainless steel is stainless and resistant to corrosion by weak media. As the amount of Cr increases, the corrosion resistance increases when Mo is added. As the C content increases, the corrosion resistance decreases. As the hardness increases, the resistance to hydrogen sulfide stress corrosion sensitivity improve. Martensitic chromium-nickel stainless steel is stainless, with Cr 17%, the corrosion resistance is similar to or slightly lower than 18-8.
Mechanical and physical properties:
With the increase of C content, martensitic chromium stainless steel increases the strength and hardness of steel, and can reach up to RC60 or more. The wear resistance of steel is good, but the toughness is poor. When Mo and V are contained, the strength of steel increases. When a small amount of Ni is contained, the strength-toughness of steel is well matched. This type of steel has brittle transition temperature, magnetic properties, small density, good shock resistance, and slightly lower modulus of elasticity than carbon steel. Martensitic chromium-nickel stainless steel has high strength (ós not less than 9800MPa) and high hardness (RC not less than 36), and has a high strength/weight ratio.
Application of materials in stainless steel bearings:
SUS304, SUS316, SUS316L: inner and outer rings in austenitic stainless steel bearings, balls, cages, rivets, bearing seats, jacking screws, dust caps, sealing ring skeletons. Cages in martensitic stainless steel bearings, rivets, bearing seats, top screws, dust caps, sealing ring skeletons.
SUS440C, SUS440B: inner and outer rings, balls in martensitic stainless steel bearings.
Detailed explanation of INA bearing steel
Bearing steel is used to make INA balls, INA rollers and INA bearing rings. INA bearings are subject to extreme pressure and friction during work, so bearing steels are required to have high and uniform hardness and wear resistance, as well as high elastic limits. The requirements for the uniformity of the chemical composition of the bearing steel, the content and distribution of non-metallic inclusions, and the distribution of carbides are all very strict. 0.5%-1.65%.
The physical properties of bearing steel are mainly based on the inspection of microstructure, decarburized layer, non-metallic inclusions and low-magnification structure. Under normal circumstances, hot rolling annealing, cold drawing annealing delivery. The delivery status should be indicated in the contract. The low-power structure of the steel must be free of shrinkage holes, subcutaneous bubbles, white spots and microscopic pores. Center looseness and general looseness shall not exceed 1.5 grades, and segregation shall not exceed 2 grades. The annealed structure of the steel should be uniformly distributed fine-grained pearlite. The depth of the decarburized layer, the non-metallic inclusions and the non-uniformity of carbides shall comply with the relevant national standards.
Bearing steel is divided into six categories: high-carbon bearing steel, non-bearing bearing steel, carburized bearing steel, stainless bearing steel, medium and high temperature bearing steel and antimagnetic bearing steel.
1. High carbon chromium bearing steel, add the symbol "G" at the head of the brand, but do not indicate the carbon content. Chromium content is expressed in parts per thousand, and other alloy elements are expressed according to the alloy content of alloy structural steel. For example: for bearing steel with an average chromium content of 1□50%, the grade is expressed as “GCr15”.
2. Carburized bearing steel, using the alloy structural steel brand representation method, plus the symbol "G" on the head of the brand. For example: "G20 CrNiMo". Premium high-quality carburized bearing steel, add "A" at the end of the grade. For example: "G20CrNiMoA".
3. High-carbon chromium stainless bearing steel and high-temperature bearing steel are represented by stainless steel and heat-resistant steel. The symbol "G" is not added to the head of the brand. For example: high-carbon chromium stainless bearing steel "9Cr18" and high-temperature bearing steel "10Cr14Mo".
How to clean INA bearings with hot oil
Bearings hardened with soft dry oil or anti-rust paste should be immersed in hot engine oil at 100-200°C, clamp the bearing with pliers, and clean the oil stain on the INA bearing with a brush. Soft dry oil or anti-rust paste is melted when heated to 100-200°C, and it is easy to wash out from the holes of the bearing. Occasionally, just shake the bearing in the oil several times. Oil stains will also drain from the holes (the rollers, bead holder, inner ring and outer ring should also be disengaged when washing). Soak the INA bearing in fire oil for 5-10 minutes, hold the inner ring with one hand, the other Turn the outer ring with only one hand, and the dry oil or anti-rust paste on the bearing will be lost. Then put the bearing in clean kerosene, wash it with a brush with gold ornaments, wash away the oil stains in the balls and holes, and then wash it in gasoline once, take it out and put it on clean paper.
Radial spherical ball bearings and short cylindrical roller bearings should be cleaned by disassembling the balls, bead holder, inner ring and outer ring.