A kind of preparation method of high plastic toughness high boron austenitic stainless steel sheet

Abstract

A method for preparing high plasticity and toughness high boron austenitic stainless steel sheets, which is carried out according to the following steps: (1) Smelting molten steel according to the set composition, the composition is according to mass percentage B 1.5-2.5%, Ti 0.5-1.5%, C<0.01 %, Cr 16.0~19.0%, Ni 14.0~16.0%, Mn 1.0~2.0%, Si 0.2~2.0%, the rest is Fe; (2) The molten steel is poured into the tundish, and the temperature of the molten steel in the tundish is controlled to meet 10°C <T‑T 0 <50℃; (3) The molten steel is solidified and exported through the tundish and between the roll gaps of the continuous caster to obtain a cast strip; (4) Hot rolling is performed one after another, and the hot rolled plate is obtained by cooling and coiling; (5) Flattened after annealing deal with. The method of the present invention finally obtains a high-boron stainless steel sheet with high plastic toughness; the production process is compact and the manufacturing process is few, which can significantly reduce the production cost.

Description

technical field [0001] The invention belongs to the technical field of metallurgical materials, in particular to a method for preparing a high-plastic-toughness high-boron austenitic stainless steel thin plate. Background technique [0002] At present, with the development of my country's nuclear industry, the amount of nuclear spent fuel unloaded from nuclear reactors has increased dramatically; due to the strong radioactivity of spent fuel, which seriously endangers the surrounding environment and human health, thermal neutron absorbing materials must be used to prepare spent fuel in the nuclear industry transportation and storage containers for spent fuel storage; thermal neutron absorbing materials used for spent fuel storage in the field of nuclear power have a harsh service environment, so the requirements for their performance are also extremely stringent; for thermal neutron absorbing materials used for spent fuel transportation containers, their During the process, it...

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Problems solved by technology

[0003] The boron content in high-boron stainless steel is generally greater than 0.1%, which has a good thermal neutron absorption effect, and its thermal neutron absorption capacity increases with the increase of boron content; however, the solid content of boron in the austenitic stainless steel matrix The solubility is very low, only 0.018-0.026%. When high-boron stainless steel is prepared by the conventional casting process, the excess boron will be biased towards the grain boundary during solidification, and a large amount of coarse and reticular distribution (Cr, Fe) will be precipitated. 2 B Hard and brittle borides, which split the austenite matrix, seriously deteriorate the mechanical properties and corrosion resistance of high-boron steel; in the subsequent thermal deformation process, high-boron stainless steel workpieces are prone to edge cracking; hard and brittle borides distributed in a network The precipitated phase leads to higher strength of the finished plate, but the plasticity and toughness at room temperature are poor, and the ability to resist deformation and damage during service is poor; therefore, the problem of low plasticity and toughness of high boron stainless steel plate limits its use in spent fuel storage and transportation. Developments in the field of nuclear industry such as containers

[0004] The powder metallurgy method is currently the main method for preparing high-boron stainless steel plates. The process is mainly to use the argon gas protection gas mist method to prepare high-boron stainless steel powder, sinter and shape it, and then perform subsequent preparation processes such as hot / cold processing; however, The current powder metallurgy method generally adopts the hot isostatic pressing process for sintering, which will make the cycle of the whole process longer, the preparation cost is relatively high, and it is difficult to achieve mass production

[0005] In recent years, some scholars have proposed to add titanium element to high boron steel, and use high temperature precipitation phase TiB 2 heterogeneous nucleation to improve (Cr,Fe) 2 The size and distribution of B borides; in the paper (DOI: 10.1016 / j.msea.2007.02.032), Fu Hanguang et al. of Xi'an Jiaotong University studied the influence of titanium on the structure and properties of high boron steel, and found that the borides containing 1.5~ After adding 0.2-0.5% Ti to 2.5% B high-boron steel, the high-temperature precipitation phase TiB in the structure 2 The size is 5 ~ 10μm, continuously distributed network (Cr, Fe) 2 B borides are partially broken, but (Cr,Fe) 2 B borides are not significantly refined, most of them are 15-25 μm; the mechanical properties test found that the elongation of high boron steel at room temperature increased from 1.04% to 1.82% after adding titanium, which was not significantly improved; in addition, Li Yongwang of Northeastern University et al. DOI: 10.1007 / s12598-019-01247-w) studied the microstructure changes after adding 2.0% Ti to 2.1% B high boron steel, and found that TiB in the microstructure 2 The size is 5~15μm, (Cr, Fe) 2 B boride distribution is more diffuse, but (Cr,Fe) 2 The size of B borides is still greater than 15 μm, and the borides are not significantly refined; analyzing the reasons, it is found that in the traditional die casting process of high boron steel, after adding titanium, the first precipitated phase TiB in molten steel 2 Due to the low density, a large amount floats on the surface of molten steel and cannot be used as (Cr, Fe) 2 Heterogeneous nucleation cores of B borides; in addition, TiB during solidification 2 It will grow excessively, and the final size will reach 5 ~ 15μm, which is beyond the size of (Cr, Fe) 2 The critical size of B boride heterogeneous nucleation core; therefore, TiB in the structure of high boron stainless steel prepared by traditional die casting process 2 and (Cr,Fe) 2 B borides are relatively coarse, and the plasticity and toughness of the thin plate are extremely poor

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