Effect Of Rare-Earth Ce On The Microstructure And Properties Of 2Cr13 Stainless Steel

Stainless steel, as iron and steel material, has many advantages, such as corrosion resistance, high strength and low life cycle costing etc, so it is extensively used in industrial facilities, water industry and so on. But China is in the first time step of studying stainless steels in construction industry, automotive industry and environmental protection industry, and has a rather large development potential. Comparing with developed countries, Chinese researching is in a low level, and stainless steels in these field of reseraching not only require good corrosion resistance, but also high strength and ductility. Rare earth can play a key role in increasing the comprehensive function of stainless steel. Therefore, the potential of rare earth in stainless steel should be fully rooted. To develop rare-earth stainless steel has important significance on continuous development of social economy.In this dissertation, the influences of RE-Ce on the microscopic structure and mechanical property of 2Cr13 stainless steel that is extensively used at the present time are systematically studied by measurements of optical microstructure, X-ray energy spectrum, scanning electronic microscope, microhardness test, tensile test and impact toughness test, according to the testing and analyzing, the results are as follows:1)Putting RE-Ce in 2Cr13 stainless steel, RE-Ce has the effectiveness of deoxygenation and desulfuration, when the solid solubility of Ce is 0.042%, the percentage composition of O in the steel is from 0.007% to 0.0016% and S is from 0.018% to 0.0071%, and this testing shows that RE-Ce has the powerful effectiveness of cleaning molten steel.2)RE-Ce modifies the shapes of the inclusions in the steel, making the shapes of the inclusions change from random geometry to globularity and effectively controls the size of the inclusions, diminishing the average particle diameter of the inclusions from large to small, so it modifies the inclusions of the steel very well.3)The stability of overcooling austenite has been increared because of putting RE-Ce in the steel, the CCT curve has been moved to right and the critical point of Ac3, Ac1, Ms, Mf has been reduced, and the precipitation of carbides has been inhibited.4) RE-Ce has increased the content of lath-shaped quenched martensites, refined the grain size of martensites, reduced the residual austenite content and inhibited the production of flaky martensites. Because of adding RE-Ce in the steel, the grain size of tempered sorbites has been refined, equiaxed grain of ferrites has been refined, carbides have been spheroidized and adequatedly distributed in the ferrite matrixes.5)The microhardness of quenched martensite has been increased, but the microhardness of tempered sorbites has been reduced by RE-Ce. The high temperature tensile strength and elongation percentage of 2Cr13 stainless steel have been increased with a small amplitude, fine-grain strengthening is the primary strengthening mechanism of 2Cr13, and the high temperature tensile fracture of 2Cr13 is fine equiaxed dimple. Because RE-Ce can modify the inclusions of the steel and purify grain-boundary, it changes cleavage fracture of the steel samples to dimple fracture.