CN-120502699-B - Preparation method of boron stainless steel sheet for thermal neutron absorption

Abstract

The invention relates to a preparation method of a boron stainless steel sheet for thermal neutron absorption, which comprises the following process steps of (1) induction smelting, (2) atomization and deposition, (3) forging and pressing, (4) hot rolling and (5) profile processing. According to the invention, through an innovative process route and reasonable smelting, plate processing deformation and heat treatment processes, the microstructure of the material is obviously improved, and the hard and brittle boride particles are thinned, so that the hot workability of the material and the mechanical properties of the finished plate are improved, and the higher requirements of the boron stainless steel sheet for thermal neutron absorption are met. The plate manufactured by the process has similar performance to powder metallurgy boron stainless steel, has excellent comprehensive performance, and has shorter process flow and lower manufacturing cost.

Inventors

• LV KAN
• LV WENTAO
• LI YONGWANG
• Ying Zonglin
• LIAO ZHIHAI
• ZHENG YUE
• QI JIE
• LIU XIAOZHEN
• WANG MEILING
• LV RONG
• HE XUEYI

Assignees

• 浙江正达新材料科技有限公司
• 晨龙集团有限责任公司

Dates

Publication Date

20260505

Application Date

20250522

Claims (3)

1. 1. The preparation method of the boron stainless steel sheet for thermal neutron absorption comprises the following steps: (1) Induction smelting, namely proportioning 304 stainless steel, ferroboron, ferrochrome and ferronickel raw materials according to the requirement, and carrying out induction smelting to obtain molten steel meeting the component requirement; (2) Pouring molten steel into a preheated tundish, enabling the molten steel to flow out through a flow guide pipe and enter an atomizer, atomizing the molten steel by adopting a double nozzle and nitrogen, accelerating atomized molten drop particles by high-pressure nitrogen, and depositing on a rotating receiving substrate to form a cylindrical deposition ingot blank; (3) Homogenizing annealing, namely placing the deposited ingot blank into an annealing furnace, and heating, preserving heat and cooling to obtain a homogenized spray ingot; (4) Forging, namely placing the homogenized and annealed spray ingot into a high-temperature furnace, heating, raising the temperature and preserving the heat, and forging into a thick plate; (5) Hot rolling, namely putting the thick plate into a high-temperature furnace again, and hot rolling the thin plate with the required thickness after heating, heating and heat preservation; (6) Profile processing, namely carrying out solution treatment on the hot rolled sheet, and then straightening and sizing and cutting to obtain a finished sheet; in the step (2) of atomization and deposition, the molten steel pouring temperature is 1550-1570 ℃, the atomization pressure is 0.40-0.50 MPa, the diameter of a flow guide pipe is 5.0-7.0 mm, the rotating speed of a substrate is 50-80 rpm, and the preheating temperature of a tundish is 900-1000 ℃; In the step (3), in the homogenizing annealing, the heating temperature is 800-900 ℃, the heating rate is 1-5 ℃ per minute, the heat preservation time is 48-144 h, and the cooling rate is 1-5 ℃ per minute; The forging and pressing in the step (4) adopts a multi-firing forging process, the maximum forging pressing amount in a single firing is not more than 50%, the heating temperature is 1050-1150 ℃, the heating rate is 5-10 ℃, the heat preservation time is 60-90 min, and the final forging temperature is not lower than 900 ℃; The hot rolling in the step (5) adopts a multi-hot rolling process, the maximum hot rolling reduction of single hot is not more than 60%, the heating temperature is 1050-1150 ℃, the heating rate is 5-10 ℃, the heat preservation time is 60-90 min, and the finishing temperature is not less than 900 ℃.
2. 2. The method for producing a boron stainless steel sheet for thermal neutron absorption according to claim 1, wherein in the induction melting in the step (1), the mass fraction of each component of molten steel is ：C：0.01～0.06％,B：1.50～1.90％,Si≤1.0％,Mn≤2.0％,P≤0.035％,S≤0.030％,Ni：12.0～15.0％,Cr：18.0～20.0％,N≤0.10％,Co≤0.20％,, and the balance is Fe and unavoidable impurities.
3. 3. The method for producing a boron stainless steel sheet for thermal neutron absorption according to claim 1, wherein the solid solution temperature in the step (6) is 1040 to 1100 ℃, the solid solution time is t, the sheet thickness is h, the unit of t is min, and the unit of h is mm, and t= (2 to 4) min/mm×h.

Description

Preparation method of boron stainless steel sheet for thermal neutron absorption Technical Field The invention belongs to the technical field of metallurgical materials, and mainly relates to a preparation method of a boron stainless steel sheet for thermal neutron absorption. Background With the vigorous development of the nuclear power industry in China, the spent fuel generated by the operation of the nuclear power station is increased year by year, and the safe storage and transportation of the spent fuel are widely paid attention to. The neutron absorption material is used as a key functional material in the material, and plays a critical role in guaranteeing the spent fuel to be in a subcritical state. Based on the excellent thermal neutron absorption characteristic of boron element, the boron-containing stainless steel is a common neutron absorption material, has good mechanical property, structural stability, corrosion resistance and thermal neutron absorption performance, and has wide application prospect in the fields of spent fuel storage and transportation. To ensure that spent fuel remains subcritical, nuclear power plants are increasingly prone to storing spent fuel in a high-density or extremely high storage density manner, which promotes the boron-containing stainless steel to be thinner and higher in boron content. However, the solid solubility of boron in steel is very low, a large amount of low-melting-point boride eutectic is formed in high-boron stainless steel, if the traditional smelting/forging process is adopted, the eutectic boride is limited by the characteristic of slow cooling and solidification of molten steel in the process, coarse hard and brittle boride tissues are easily formed in the solidification process, the eutectic boride is segregated in a crystal boundary to form net distribution, a matrix is severely split, the crystal boundary strength is greatly weakened, the plasticity and toughness of the material are greatly reduced, the hot workability of the steel is remarkably deteriorated, the edge cracking of a steel plate is serious, the manufacturing difficulty of the boron-containing stainless steel sheet is high, the yield is low, and the manufacturing cost is greatly increased. In order to improve the toughness of the boron-containing stainless steel and improve the hot workability of the material, the U.S. Carpenter company adopts prealloying and gas atomization powder metallurgy technology to produce the boron-containing stainless steel, and the boron-containing stainless steel has larger ductility than the traditional cast boron-containing stainless steel, reduces the manufacturing difficulty and improves the yield, because the powder metallurgy boron stainless steel avoids the generation of coarse boride eutectic structures and the reticular continuous distribution along grain boundaries, and boride in the steel is in small particles and uniformly distributed, and an austenite matrix is continuous and is not cut by the boride structures. However, the powder metallurgy process is complex, the flow is long, the production cost and the energy consumption are high, the product price is high, and the wide application of the powder metallurgy boron stainless steel is limited. In summary, how to improve the hot workability of materials with lower process cost is a technical problem to be solved in the current preparation of boron-containing stainless steel. The injection molding process provides a way to solve this problem. Compared with the powder metallurgy technology, the spray forming technology combines liquid metal atomization (rapid solidification) and atomized liquid drop deposition, and the metallurgical forming operation is completed in one step, so that the process is short and high in efficiency, and the problems that boron is easy to segregate and gather to form a net shape in the preparation process of the traditional casting and forging process and the cost is increased due to the long process flow of the powder metallurgy are hopefully solved. Disclosure of Invention The invention provides a preparation method of a boron stainless steel sheet for thermal neutron absorption, which aims to solve the problems of low hot workability, high cost and the like caused by long process flow of the existing cast-forging boron stainless steel sheet and powder metallurgy boron stainless steel sheet. The boron stainless steel spray ingot with fine boride and uniform distribution is prepared by the process of induction smelting, spray forming and annealing homogenization. On the premise of ensuring that the blank does not crack, the processing technology based on forging blank forming, hot rolling blank forming and solution treatment improves the deformation of the boron stainless steel plate blank, reduces the number of fires in the hot processing process, realizes the regulation and control of refinement and distribution diffusion of boride structures of the finished