With the help of X-ray diffraction, scanning electron microscope, transmission electron microscope, hardness test and micro-tensile test, the structure and properties of AISI310S austenitic stainless steel after large deformation at different temperatures are analyzed. The analysis results show that after large deformation at different temperatures, the austenitic stainless steel structure does not undergo strain-induced martensitic transformation under different deformations. When the amount of deformation is small, the microstructure is dominated by high-density dislocations and dislocation entanglements; as the amount of deformation increases, the microstructure is dominated by deformation twins; when the amount of deformation increases to 90% , The grain size of austenitic stainless steel is refined to nanometer level, and the degree of grain refinement in cryogenic cold rolling is significantly higher than that in room temperature cold rolling. The yield strength, tensile strength and hardness of the cryogenic cold rolled state are also higher than that of the room temperature cold rolled state. As the amount of deformation increases, the elongation decreases significantly, and the morphology of the tensile fracture changes from ductile fracture to quasi-cleavage fracture.
Cryogenic treatment affects the corrosion and wear resistance of AISI 310S stainless steel in 3.5% (mass fraction) Na Cl solution. The 310S stainless steel is subjected to thermal insulation and cryogenic treatment at -196°C. The results show that: The grains are refined, and more carbides are dispersed and precipitated out of the matrix; after cryogenic treatment, the corrosion resistance of the material is improved, reaching the best value at 4 h after cryogenic treatment, and the self-corrosion potential is increased from -0.525 V compared with no cryogenic treatment To -0.423 V, an increase of 19.4%; and after cryogenic treatment, the corrosion resistance of the material is improved. After cryogenic treatment for 4 hours, the wear rate of the material is reduced from 120×10-6mm3/Nm to 63×10-6mm3/ Nm, reduced by 90%.
Designed and built a circulating flow experiment device to simulate the corrosion environment of the top circulation system of the sewage stripping device. Using electrochemical test methods and surface analysis techniques, the corrosion behavior and characteristics of 316L stainless steel (316L SS) in the sewage medium were studied. . The experimental results show that the corrosion form of 316L SS in the sewage medium is local pitting corrosion, and the corrosion surface has scattered pits. The content of NH4Cl in the sewage medium and the flow rate of the medium are the key factors affecting the corrosion rate of 316L SS. When the mass fraction of NH4Cl in the sewage medium is less than 4.0%, the corrosion system impedance is large, and the anodic polarization curve of 316L SS shows a typical dissolution, passivation and pitting process; when the mass fraction of NH4Cl is greater than 4.0%, the polarization curve There is no obvious passivation zone, and the impedance radius of the system decreases sharply at this time, indicating that a complete passivation film is not formed on the surface of 316L SS, and the corrosion resistance of the material is reduced. When the mass fraction of NH4Cl in the sewage is 4.0% and the medium flow rate is greater than 1.0 m/s, the corrosion rate of 316L SS increases sharply.
China construction rebar and hot rolled coil futures due to weak downstream demandHowever, after Shandong Province announced a production cut, the price of raw materials rose driven by coke.Apparent consumption decreased by 4.7% to 10.97 MnTThe off-season is gradually coming, and the consumption decline is affected by the high temperature and rain in the southern region, and the destocking of (steel) is about to end.The rebar with the largest volume for October delivery on the Shanghai Futures Exchange closed down 1.5% to 5,168 yuan/ton ($807.44)/MT)Hot rolled coil futures used in manufacturing fell 1.9% to RMB 5,436/ton. Shanghai stainless steel futures for delivery in July rose slightly by 0.5% to 16,390 yuan/tonHowever, despite the weight of steel millsThe utilization rate is low, but the price of steelmaking raw materials has recovered from the early decline. As of June 11, the blast furnace capacity utilization rate of 163 steel plants in China has fallen to 80.69%, the lowest level since mid-MayBenchmark iron ore futures will be delivered on the Dalian Commodity Exchange in SeptemberThe spot price of iron ore rose slightly by 0.9% to RMB 1,226/ton, and the spot price of iron ore with 62% iron content rose to US$7 to US$220. Dalian coking coal futures rose 1.3% to RMB 1,956/tonCoke futures rose 2.3% to RMB 2,725/tonChina's Shandong Province has pledged to limit its coke production to 32 MnT in 2021 and reduce its coking capacity from 46 MnT to 33 MnT