Research On Mechanical And Corrosion Properties Of Boiler Steel

Microhardness and half width of X-ray diffraction lines are often used as a material strengthening of characterization parameters. Microhardness of the material elasticity, plasticity, work hardening index, related to the strength and toughness, the material strength is the characterization of a composite index. And X-ray diffraction line half width of characterizing the structure of the state of the material, only indirectly reflects its mechanical properties. The experimental results show that many of the past, the greater the hardness of the material, its FWHM of X-ray diffraction lines of the greater, and the establishment of a number corresponding to the empirical formula based on this. But it also found that the second parameter variation in the processing of deformed layer is inconsistent.In this paper, two different temperatures tempered steel materials 20g ultra-high-strength steel and 12Cr1MoV, discussed in the regular stretching, FWHM impact plastic deformation of the micro-hardness and X-ray diffraction lines and using X-ray linear analysis techniques to obtain a sample of mosaic block size, micro-strain and dislocation density, microstructure parameters, to discuss its microscopic mechanisms.As the tempering temperature, the tensile strength 20g high strength steel and spring steel 12Cr1MoV reduced elongation increases. This is mainly because as the tempering temperature, the precipitation of carbides grow up together, plus softening-Fe matrix reply caused, resulting in decreased strength and hardness, elongation increased. And with the increase of plastic deformation, the flow stress is increasing, so the material hardening occurs.For the steel material tempered at different temperatures, with the increase of microhardness of plastic deformation amount increases. Plastic deformation can be reduced FWHM hard abnormal state of the material, which is mainly due to plastic deformation so that the microstructure of the strained material is reduced due to abnormality. Machining or surface deformation hardening process will be introduced in the sample or plastic deformation of the workpiece surface, then if FWHM strengthen or weaken as a surface characterization parameters, it is possible to get wrong conclusions. With the increase of the residual stress in the surface of the plastic deformation is increased, this may be due to the deformation of the specimen and the surface of the core section caused by uneven.During tensile test, for steel in soft state, microhardness and half width increase with the augmentation of plastic deformation, the increase of half width results from refining mosaic block and enhancing of microstrain. For steel in hard state, microhardness is increased but their half width and dislocation density are decreased abnormally, owing to the abnormal decrease of microstrain. The abnormal decrease of half width illuminates that half width may guide false information if it is utilized to characterize the hardening or softening of steel.In addition to the corrosion rate of 20g steel in saline solution and increased with increasing temperature. Corrosion is mainly controlled by the catholic polarization control. Corrosion rate of 20g steel in hydrochloric acid aqueous solution increased with increasing the concentration of hydrochloric acid. Corrosion was controlled by catholic reduction. The concentration of hydrochloric acid is low, the depolarization reaction controlled by H+. When hydrochloric acid above a certain concentration, by concentration polarization control.