阅读说明：本技术 耐液态铅铋腐蚀的高强度Fe-Cr-Zr-W-Mo-B铁素体合金及其制备方法 (High-strength Fe-Cr-Zr-W-Mo-B ferrite alloy resistant to liquid lead and bismuth corrosion and preparation method thereof ) 是由 陈胜虎 戎利建 姜海昌 闫德胜 赵明久 王本贤 胡小峰 宋元元 张杨鹏 于 2020-05-25 设计创作，主要内容包括：本发明公开了一种耐液态铅铋腐蚀的高强度Fe-Cr-Zr-W-Mo-B铁素体耐热合金及其制备方法,属于耐热合金材料技术领域。合金化学成分为：C≤0.01％；Cr：8.0～12.0％；Mo：0～2.0％；W：0～2.0％；Zr：5.0～10.0％；B：10～50ppm；Fe余量。本发明在Fe-(9～12wt.％)Cr的基础上,添加Zr使得基体中析出Fe-Zr金属间相,其弥散强化作用提高材料的高温强度；B的添加可将铁素体基体的晶粒尺寸细化至1微米以下,细小的晶粒尺寸提高了合金的耐液态铅铋腐蚀性能。本发明的Fe-Cr-Zr-W-Mo-B铁素体合金满足了对耐高温、耐铅铋腐蚀、抗辐照的性能要求。(The invention discloses a high-strength Fe-Cr-Zr-W-Mo-B ferrite heat-resistant alloy resistant to liquid lead and bismuth corrosion and a preparation method thereof, belonging to the technical field of heat-resistant alloy materials. The alloy comprises the following chemical components: c is less than or equal to 0.01 percent; cr: 8.0-12.0%; mo: 0 to 2.0 percent; w: 0 to 2.0 percent; zr: 5.0-10.0%; b: 10 to 50 ppm; the balance of Fe. According to the invention, on the basis of Fe- (9-12 wt.%) Cr, Zr is added to precipitate Fe-Zr intermetallic phase in the matrix, and the dispersion strengthening effect of the Zr improves the high-temperature strength of the material; the addition of B can refine the grain size of the ferrite matrix to be less than 1 micron, and the fine grain size improves the liquid lead bismuth corrosion resistance of the alloy. The Fe-Cr-Zr-W-Mo-B ferrite alloy meets the performance requirements on high temperature resistance, lead-bismuth corrosion resistance and irradiation resistance.)

1. A high-strength Fe-Cr-Zr-W-Mo-B ferrite alloy resisting liquid lead and bismuth corrosion is characterized in that: the alloy comprises the following chemical components in percentage by weight:

c is less than or equal to 0.01 percent; cr: 8.0-12.0%; mo: 0 to 2.0 percent; w: 0 to 2.0 percent; zr: 5.0-10.0%; b: 10 to 50 ppm; the balance being Fe.

2. The high strength Fe-Cr-Zr-W-Mo-B ferritic alloy with resistance to corrosion by liquid lead bismuth according to claim 1, characterized in that: the alloy comprises the following chemical components in percentage by weight:

c: 0.001-0.008%; cr: 9.0-10.5%; mo: 0.2-1.8%; w: 0.3-1.8%; zr: 7.5-10.0%; b: 20 to 50 ppm; the balance being Fe.

3. The high strength Fe-Cr-Zr-W-Mo-B ferritic alloy with resistance to corrosion by liquid lead bismuth according to claim 1 or 2, characterized in that: in the chemical composition of the alloy, Mo and W account for 1.0-3.0 wt.%.

4. The high strength Fe-Cr-Zr-W-Mo-B ferritic alloy with resistance to corrosion by liquid lead bismuth according to claim 1, characterized in that: the microstructure of the Fe-Cr-Zr-W-Mo-B ferrite alloy consists of Fe₂Zr phase and α -Fe phase, Fe₂Zr phase dispersed in ferrite matrix (α -Fe phase), Fe₂The Zr phase is in micron level, and the grain size of the ferrite matrix is less than 1 micron.

5. The high strength Fe-Cr-Zr-W-Mo-B ferritic alloy with resistance to corrosion by liquid lead bismuth according to claim 1, characterized in that: the yield strength of the Fe-Cr-Zr-W-Mo-B ferrite alloy under the service condition of 700 ℃ is more than 210MPa, the tensile strength is more than 250MPa, and the elongation is more than 40.0%.

6. The method of making a high strength Fe-Cr-Zr-W-Mo-B ferritic alloy with resistance to corrosion by liquid lead bismuth according to claim 1, wherein: firstly, weighing raw materials according to the alloy component proportion, smelting the raw materials in a vacuum induction furnace, and casting into an ingot; forging and rolling the cast ingot, and carrying out heat treatment on the rolled plate to obtain the high-strength Fe-Cr-Zr-W-Mo-B ferrite alloy; the heat treatment system is as follows:

(1) carrying out solid solution treatment at 1050-1150 ℃, keeping the temperature for 5-30 min, and air cooling to room temperature;

(2) aging at 700-780 ℃, preserving heat for 1-3 h, and cooling to room temperature.

7. The method of making a high strength Fe-Cr-Zr-W-Mo-B ferritic alloy with resistance to corrosion by liquid lead bismuth according to claim 6, wherein: the ingot casting forging process comprises the following steps: heating the cast ingot to 1150 ℃, preserving heat for 1h, forging the cast ingot into a slab on a hammer forging machine, and then air-cooling the slab to room temperature, wherein the final forging temperature is above 900 ℃.

8. The method of making a high strength Fe-Cr-Zr-W-Mo-B ferritic alloy with resistance to corrosion by liquid lead bismuth according to claim 6, wherein: the rolling process after ingot casting forging is as follows: heating the forged plate to 1150 ℃, preserving heat for 1h, rolling the plate on a two-roll hot rolling mill to form the plate, and then air-cooling the plate to room temperature, wherein the final rolling temperature is above 900 ℃.

The technical field is as follows:

the invention relates to the technical field of heat-resistant alloy materials, in particular to a high-strength Fe-Cr-Zr-W-Mo-B ferrite alloy resistant to liquid lead and bismuth corrosion and a preparation method thereof.

Background art:

nuclear power is used as low-carbon energy and is an important basis for sustainable development of future energy. Along with the large-scale development of nuclear power in China, the generation amount of spent fuel is increased day by day. In order to ensure the safe and sustainable development of nuclear power, advanced nuclear energy systems including four-generation fast reactors and closed fuel circulation technologies thereof and more advanced ADS (accelerator driven subcritical system) fuel circulation technologies are actively developed in countries with developed international nuclear technologies, so that the utilization rate of uranium resources in spent fuels is improved and long-life radioactive wastes are reduced. The lead-bismuth eutectic (LBE) alloy has the advantages of excellent neutron performance, chemical inertness, thermal physical performance, radiation resistance and the like, and is considered as a preferred material for a four-generation lead-cooled fast reactor coolant, an ADS system spallation target and a coolant.

Compared with austenitic stainless steel, ferrite/martensite heat-resistant steel, such as T91, 9Cr2WVTa, F82H, CLAM, Eurofer97, EP823 and the like, is regarded as a main candidate structural material of a four-generation nuclear energy system and an ADS system due to the characteristics of small thermal expansion coefficient, high thermal conductivity, small radiation swelling rate and the like. The material not only plays a role in guaranteeing the normal work of the nuclear energy system, but also directly determines the efficiency of the nuclear energy system through the bearable service temperature. The main alloy component of the ferrite/martensite heat-resistant steel is Fe- (9-12 wt.%) Cr, and the good high-temperature strength of the ferrite/martensite heat-resistant steel is mainly determined by interfaces (including original austenite crystal boundaries, martensite lath boundaries and lath internal subgrain boundaries) formed after quenching and tempering treatment and M precipitated at the interfaces₂₃C₆CarbonizingA compound (I) is provided. However, M at the interface under long-term action at high temperatures₂₃C₆The carbide can undergo Ostwald coarsening, which causes the strength of the material to be remarkably reduced, so that the service temperature of the material does not exceed 550 ℃. Therefore, how to improve the high-temperature strength of ferrite/martensite heat-resistant steel is a problem to be solved urgently. The high-temperature strength of the material can be obviously improved by introducing the ferrite/martensite steel preparation process into the Oxide Dispersion Strengthening (ODS) technology, the dispersion distributed oxide particles play a role in dispersion strengthening, and meanwhile, the oxide particles can be nailed and rolled in dislocation and grain boundaries to ensure the stability of the structure. Although the ODS steel has an attractive application prospect, the current preparation technology of the ODS steel needs to be further improved.

The invention content is as follows:

in order to solve the problem that the strength of ferrite/martensite steel is reduced at the high temperature of more than 550 ℃, the invention aims to develop a Fe-Cr-Zr-W-Mo-B alloy reinforced by Fe-Zr type intermetallic compounds on the basis of Fe- (9-12 wt.%) Cr, so that the high-temperature strength of the alloy is improved while the corrosion resistance of liquid lead and bismuth is ensured.

In order to achieve the purpose, the technical scheme of the invention is as follows:

the high-strength Fe-Cr-Zr-W-Mo-B ferrite alloy resisting liquid lead and bismuth corrosion comprises the following chemical components in percentage by weight:

c is less than or equal to 0.01 percent; cr: 8.0-12.0%; mo: 0 to 2.0 percent; w: 0 to 2.0 percent; zr: 5.0-10.0%; b: 10 to 50 ppm; the balance being Fe.

The alloy preferably comprises the following chemical components in percentage by weight:

c: 0.001-0.008%; cr: 9.0-10.5%; mo: 0.2-1.8%; w: 0.3-1.8%; zr: 7.5-10.0%; b: 20 to 50 ppm; the balance being Fe.

In the chemical composition of the alloy, Mo and W account for 1.0-3.0 wt.%.

The microstructure of the Fe-Cr-Zr-W-Mo-B ferrite alloy consists of Fe₂Zr phase and α -Fe phase, Fe₂Zr phase dispersed in ferrite matrix (α -Fe phase), Fe₂The Zr phase is in micron level, and the grain size of the ferrite matrix is less than 1 micronAnd (4) rice.

The yield strength of the Fe-Cr-Zr-W-Mo-B ferrite alloy under the service condition of 700 ℃ is more than 210MPa, the tensile strength is more than 250MPa, and the elongation is more than 40.0%.

The preparation method of the Fe-Cr-Zr-W-Mo-B ferrite alloy comprises the following steps: firstly, weighing raw materials according to the alloy component proportion, smelting the raw materials in a vacuum induction furnace, and casting into an ingot; forging and rolling the cast ingot, and carrying out heat treatment on the rolled plate to obtain the high-strength Fe-Cr-Zr-W-Mo-B ferrite alloy; the heat treatment system is as follows:

(1) carrying out solid solution treatment at 1050-1150 ℃, keeping the temperature for 5-30 min, and air cooling to room temperature;

(2) aging at 700-780 ℃, preserving heat for 1-3 h, and cooling to room temperature.

The ingot casting forging process comprises the following steps: heating the cast ingot to 1150 ℃, preserving heat for 1h, forging the cast ingot into a slab on a hammer forging machine, and then air-cooling the slab to room temperature, wherein the final forging temperature is above 900 ℃.

The rolling process after the ingot casting forging is as follows: heating the forged plate to 1150 ℃, preserving heat for 1h, rolling the plate on a two-roll hot rolling mill to form the plate, and then air-cooling the plate to room temperature, wherein the final rolling temperature is above 900 ℃.

The design mechanism of the invention is as follows:

the invention utilizes the dispersed intermetallic phase to improve the strength, and simultaneously refines the ferrite grain size to improve the corrosion resistance. Based on the design concept, the Fe-Cr-Zr-W-Mo-B ferrite alloy is designed on the basis of Fe- (9-12 wt.%) Cr: (1) reducing C content to avoid poor thermal stability of M₂₃C₆Formation of carbides; (2) precipitating Fe-Zr intermetallic phases which are dispersed and distributed in the matrix by adding Zr; (3) the addition of W and Mo improves the high-temperature strength of the matrix and improves the strength matching of the matrix and Fe-Zr intermetallic phases; (4) b is added to refine the grain size of the matrix and improve the corrosion resistance of the alloy, thereby obtaining the high-strength Fe-Cr-Zr-W-Mo-B ferrite alloy resisting the corrosion of the liquid lead and bismuth.

The invention has the advantages and beneficial effects that:

1、on the basis of Fe- (9-12 wt.%) Cr, the Fe-Cr-Zr-W-Mo-B ferrite alloy with Fe-Zr intermetallic phase dispersion strengthening is developed, and on one hand, the C content is reduced (the C content is controlled to be less than or equal to 0.01%) to avoid M with poor thermal stability₂₃C₆Precipitation of carbide; on the other hand, by adding a proper amount of Zr (the Zr content is controlled to be 5.0-10.0%), an Fe-Zr intermetallic phase is precipitated in the matrix, so that the dispersion strengthening effect is ensured. The Fe-Zr intermetallic phase has good thermal stability, and the dispersion strengthening effect of the Fe-Zr intermetallic phase is beneficial to improving the high-temperature performance of the material.

2. According to the high-strength Fe-Cr-Zr-W-Mo-B ferrite alloy resistant to liquid lead and bismuth corrosion, the proper amount of B (10-50 ppm) is added, so that the grain size of a ferrite matrix can be refined to be below 1 micron, and excessive B is prevented from forming boride while the purpose of refining the grain size is achieved; meanwhile, the stability of the grain size is ensured by the nail rolling effect of Fe-Zr intermetallic relative grain boundary. The fine grain size improves the liquid lead bismuth corrosion resistance of the material.

3. According to the high-strength Fe-Cr-Zr-W-Mo-B ferrite alloy resistant to liquid lead and bismuth corrosion, Mo and W are added to improve the high-temperature strength of a matrix, in order to ensure the solid solution strengthening effect of Mo and W and avoid excessive Mo and W from forming harmful Laves phases, the sum of the mass fractions of Mo and W is preferably 1.0-3.0%.

4. The high-strength Fe-Cr-Zr-W-Mo-B ferrite alloy resistant to liquid lead and bismuth corrosion is remarkably superior to the existing 9Cr ferrite/martensite steel in high-temperature tensile strength and equivalent to (9-12 Cr) -ODS steel in performance; meanwhile, the alloy has good liquid lead-bismuth corrosion resistance, and is equivalent to the existing 9Cr ferrite/martensite steel and (9-12 Cr) -ODS steel.

5. The preparation method of the alloy is simple and easy to operate. The adopted process equipment is conventional equipment, the cost is low, and the popularization is good.

Description of the drawings:

FIG. 1 is a structural photograph (observed by SEM at 5000 times) of a Fe-Cr-Zr-W-Mo-B ferritic alloy prepared by example.

FIG. 2 is a photograph of the structure of the ferrite matrix in the Fe-Cr-Zr-W-Mo-B ferrite alloy prepared in example (transmission electron microscopy).

FIG. 3 is a photograph showing the cross-sectional shape of a Fe-Cr-Zr-W-Mo-B ferrite alloy after being corroded for 500 hours in liquid lead bismuth with a saturated oxygen concentration at 550 ℃ (observed by a scanning electron microscope at 5000 times).

The specific implementation mode is as follows:

the high strength Fe-Cr-Zr-W-Mo-B ferritic alloy resistant to corrosion by liquid lead bismuth according to the present invention will be further described by way of examples.