Research On Spent Fuel Storage Material (boron Steel) Are

Boron stainless steel have the ability to absorb neutrons and gamma rays. It also has high strength and good toughness. Boron element in steel also will increase the hardenability of steel, and more importantly, it can ease unfavourable effect of irradiation on stainless steel. Thus, the boron stainless steel could be used as both shielding and structural material. However, the stainless steel with a great quantity of addition of boron which suffers easily risk of excess boride precipitation deteriorates properties of mechanical property, corrosion resistance and hot workability, leading to increase in difficulty for alloy to process. The high cost of development of boron-containing stainless steel, which could not meet the need of engineering structure, makes it difficult for practical application. In recent years, how to solve storage problem of nuclear waste is very important due to Chinese endeavor for development of nuclear industry. Nevertheless, at present, application of boron alloyed stainless steel in the country almost depends on import. Therefore, investigation of boron-containing stainless steel is of great significance as it could realize nationalization of shielding steel.In this paper, through a large number of experimental studies mechanical property, corrosion resistance and hot workability of stainless steel with different boron content under different solution condition and ones containing various boron were investigated. The optimum regime for heat treatment and heat process of alloy is achieved by studying effect of thermal treatment, hot work and boron element on properties of steel, providing theory guidance for the practical production of boron alloyed stainless steel. The following conclusions are drawn from the investigation.1、In this paper, solution treatment on precipitation of boride in boron austenitic stainless steel and the material mechanics performance has litter impact. After1100℃,1h, solution treatment, the pitting and intergranular corrosion resistance performance of boron stainless steel perform optimum.2、There exists as the second phase of boride due to the pinning effect prevents the austenitic grain size grew up, refining the grain size.3、when on the edge of the melting point temperature1260℃, a large number of precipitated phase in the0.5%boron content steel reduced, the grain growth faster, once more than the temperature, the material should be melt and failure.4、The solidification microstructure of boron alloyed austenitic stainless steel consisted of primary austenite and eutectic borides of (FeCr)2B.The amount of eutectic borides increased with boron content.5、The study shows that the precipitation of solution treated experimental steel is (FeCr)2B which is mechanical mixture of CrB and Fe2B. The boride precipitations containing a little of nickel and microscale manganese element were distributed mainly on the grain boundary and also partially within the grains.6、The boron dissolved in austenitic matrix contributed to solution strengthening and to the hardness. Boride precipitated phase has high hot stability and hard brittle, which could decrease toughness and increase rigidity, even cause brittle failure.With the increase of boron content, boron increases the strength of the stainless steel and drops the ability of plastic and resistance to pitting and intergranular corrosion which is inversely proportional to the amount of precipitation of boride.7、In the hot plastic simulation experimental conditions of this paper, The best hot working temperature region of boron stainless steel is1000～1150℃.With the increase of B content, the hot working region of boron stainless steel became narrowed, and the temperature of the high-temperature plastic dropping to zero gradually reduced.