阅读说明：本技术 一种铪锆钛增强奥氏体不锈钢及其制备方法 (Hafnium zirconium titanium reinforced austenitic stainless steel and preparation method thereof ) 是由 张中武 李俊澎 于 2019-09-24 设计创作，主要内容包括：本发明公开一种铪锆钛增强奥氏体不锈钢及其制备方法,该奥氏体不锈钢的元素组成如下：按质量百分比计,C≤0.05,Ni＝8.0～13.0,Cr＝18.0～22.0,Ti≤0.1,0.05≤Hf≤0.4,0.05≤Zr≤0.3,Mn≤2.0,Si≤1.0,P≤0.035,S≤0.030,余量为Fe。其制备方法包括下述步骤：(1)不锈钢的冶炼与铸造；(2)热轧开坯；(3)冷轧变形；(4)高温热处理。本发明的不锈钢中添加锆、铪和钛,不仅能提升强度,还能提高该奥氏体不锈钢的耐辐照性能,在80℃0.5mol/L的H<Sub>2</Sub>SO<Sub>4</Sub>电解液中,该奥氏体不锈钢的腐蚀速率为20.3～32.7μA/cm<Sup>2</Sup>,而且,该奥氏体不锈钢的塑性高于49％,抗拉强度高于730MPa。(The invention discloses a hafnium zirconium titanium reinforced austenitic stainless steel and a preparation method thereof, and the austenitic stainless steel comprises the following elements: according to the mass percentage, C is less than or equal to 0.05, Ni is 8.0-13.0, Cr is 18.0-22.0, Ti is less than or equal to 0.1, Hf is less than or equal to 0.05 and less than or equal to 0.4, Zr is less than or equal to 0.05 and less than or equal to 0.3, Mn is less than or equal to 2.0, Si is less than or equal to 1.0, P is less than or equal to 0.035, S is less than or equal to 0.030, and the balance is Fe. The preparation method comprises the following steps: (1) smelting and casting stainless steel; (2) hot rolling and cogging; (3) cold rolling deformation; (4) and (4) high-temperature heat treatment. Disclosure of the inventionThe addition of zirconium, hafnium and titanium in the stainless steel can not only improve the strength, but also improve the radiation resistance of the austenitic stainless steel, and the H content is 0.5mol/L at 80 DEG C 2 SO 4 In the electrolyte, the corrosion rate of the austenitic stainless steel is 20.3-32.7 muA/cm 2 Moreover, the plasticity of the austenitic stainless steel is higher than 49%, and the tensile strength is higher than 730 MPa.)

1. A hafnium zirconium titanium reinforced austenitic stainless steel, characterized by, the elemental composition of the austenitic stainless steel is as follows: according to the mass percentage, C is less than or equal to 0.05, Ni is 8.0-13.0, Cr is 18.0-22.0, Ti is less than or equal to 0.1, Hf is less than or equal to 0.05 and less than or equal to 0.4, Zr is less than or equal to 0.05 and less than or equal to 0.3, Mn is less than or equal to 2.0, Si is less than or equal to 1.0, P is less than or equal to 0.035, S is less than or equal to 0.030, and the balance is Fe.

2. A method of making the hafnium zirconium titanium reinforced austenitic stainless steel of claim 1, comprising the steps of:

(1) selecting raw materials of pure iron, metal chromium, metal nickel, metal manganese, metal hafnium, metal titanium, metal zirconium, iron silicon and iron carbon blocks according to the mass percentage of each element in the stainless steel, smelting and casting to form an alloy ingot;

(2) hot rolling and cogging;

(3) cold rolling deformation;

(4) and (4) high-temperature heat treatment.

3. The method for preparing the hafnium zirconium titanium reinforced austenitic stainless steel as set forth in claim 2, wherein the smelting and casting processes are performed in vacuum or argon protection in the step (1), and the metal solution is uniformly mixed by using a magnetic stirring technique in the smelting process.

4. The method for preparing a hafnium zirconium titanium reinforced austenitic stainless steel as set forth in claim 2, wherein the hot rolling cogging in the step (2) is performed under the following process conditions: heating the casting blank to 1100-1300 ℃, preserving heat for 10-24 hours, and then discharging for rolling; the starting temperature of hot rolling is more than or equal to 1050 ℃, the finishing temperature is more than or equal to 900 ℃, and the total hot rolling load of the plate is more than or equal to 40%.

5. The method for preparing a hafnium zirconium titanium reinforced austenitic stainless steel as set forth in claim 2, wherein the process conditions of the cold rolling deformation in the step (3) are: the total rolling reduction of cold rolling is more than or equal to 40 percent.

6. The method for preparing a hafnium zirconium titanium reinforced austenitic stainless steel as set forth in claim 2, wherein the process conditions of the high temperature heat treatment in the step (4) are: after cold rolling deformation, annealing treatment is carried out at 850-1000 ℃, and the heat preservation time is 60-120 minutes; after annealing, water quenching is adopted for rapid cooling.

Technical Field

The invention relates to hafnium zirconium titanium reinforced austenitic stainless steel and a preparation method thereof, belonging to the field of austenitic stainless steel.

Background

In the face of the current increasingly severe resource, energy and environmental problems, sustainable development of energy is becoming more important. Nuclear power is one of the important sources for large-scale sustainable electric energy supply in the world today. The nuclear power plant is a new type of power plant that utilizes the energy in the nuclear power plant to generate electricity on a large scale. Nuclear power currently accounts for approximately 16% of the total world power production. The austenitic stainless steel is widely applied to the field of nuclear power with excellent corrosion resistance, but is also very easy to be corroded by corrosive ions, stress corrosion and pitting corrosion occur, and the irradiation resistance and the mechanical property of the austenitic stainless steel are sharply reduced under the irradiation condition of high dose. Therefore, the irradiation resistance, corrosion resistance and mechanical properties of austenitic stainless steel need to be stably improved in service in a reactor.

The invention patent application with publication number CN 109355590A discloses a copper-hafnium corrosion-resistant reinforced austenitic stainless steel and a preparation method thereof, wherein the components of the austenitic stainless steel are equal to or less than 0.07 of C, 8.0-10.0 of Ni, 17.0-19.0 of Cr, equal to or less than 1.04 of Hf, 0.2-0.8 of Cu, equal to or less than 2.0 of Mn, equal to or less than 1.0 of Si, equal to or less than 0.035 of P, equal to or less than 0.030 of S, and the balance of Fe; the corrosion rate of the alloy in a 0.5mol/L sulfuric acid solution at 80 ℃ is 10.8-12.5 mu A/cm²The yield strength is 300-320 MPa, the tensile strength is 590-610 MPa, and the plasticity is 41-45%.

The invention patent application of publication No. CN 109355595A discloses a copper-hafnium-cobalt modified stainless steel and a processing and heat treatment method thereof, wherein the components of the austenitic stainless steel are that C is less than or equal to 0.03, Ni is 12.0-15.0, Cr is 16.0-18.0, Mo is 2.0-3.0, Hf is less than or equal to 0.74, Cu is 0.2-0.8, Co is 0.1-0.5, Mn is less than or equal to 2.0, Si is less than or equal to 1.0, P is less than or equal to 0.035, S is less than or equal to 0.030, and the balance is Fe; the corrosion rate of the alloy in a 0.5mol/L sulfuric acid solution at the temperature of 80 ℃ is 1.26-1.82 mu A/cm2, the yield strength is 150-160 MPa, the tensile strength is 520-540 MPa, and the plasticity is 42-47%.

Although the two technical schemes can enhance the performance of the austenitic stainless steel to a certain degree, the corrosion resistance, the mechanical property or the plasticity of the obtained austenitic stainless steel are still low; in addition, the two technical schemes both adopt copper for modification, and although copper can promote crystallization, the copper is easy to generate hot brittleness in the hot processing process, so that the mechanical property of the copper is not stable enough, and the copper is beneficial to certain extent in the industrial production process.

Disclosure of Invention

The purpose of the invention is as follows: aiming at the problems of lower irradiation resistance, corrosion resistance, mechanical property and the like of the conventional austenitic stainless steel, the invention provides a hafnium zirconium titanium reinforced austenitic stainless steel and a preparation method thereof.

The technical scheme is as follows: the invention relates to hafnium zirconium titanium reinforced austenitic stainless steel, which comprises the following elements: according to the mass percentage, C is less than or equal to 0.05, Ni is 8.0-13.0, Cr is 18.0-22.0, Ti is less than or equal to 0.1, Hf is less than or equal to 0.05 and less than or equal to 0.4, Zr is less than or equal to 0.05 and less than or equal to 0.3, Mn is less than or equal to 2.0, Si is less than or equal to 1.0, P is less than or equal to 0.035, S is less than or equal to 0.030, and the balance is Fe.

The preparation method of the hafnium zirconium titanium reinforced austenitic stainless steel comprises the following steps:

(1) selecting raw materials of pure iron, metal chromium, metal nickel, metal manganese, metal hafnium, metal titanium, metal zirconium, iron silicon and iron carbon blocks according to the mass percentage of each element in the stainless steel, smelting and casting to form an alloy ingot;

(2) hot rolling and cogging;

(3) cold rolling deformation;

(4) and (4) high-temperature heat treatment.

After the alloy is smelted, the carbide in the alloy can be fully crushed and dispersed and distributed through hot rolling cogging and cold rolling deformation, and then a uniform austenite structure can be obtained through high-temperature solution treatment, so that the alloy has high strength and corrosion resistance.

Preferably, in the step (1), the smelting and casting processes are performed in vacuum or under argon protection, and the metal solution can be uniformly mixed by using a magnetic stirring technology in the smelting process.

In the step (2), the process conditions for hot rolling and cogging are preferably as follows: heating the casting blank to 1100-1300 ℃, preserving heat for 10-24 hours, and then discharging for rolling; the starting temperature of hot rolling is more than or equal to 1050 ℃, the finishing temperature is more than or equal to 900 ℃, and the total hot rolling load of the plate is more than or equal to 40%. The pipes, rods, wires, sections, cold punching parts and cast ingots can be cogging by hot forging, hole-pattern rolling or universal rolling.

In the step (3), cold deformation can be carried out by adopting a reciprocating tube rolling, hole pattern rolling, universal rolling or drawing method so as to obtain the required size and specification of the product. Preferably, the process conditions of cold rolling deformation are as follows: the total rolling reduction of cold rolling is more than or equal to 40 percent. The large cold rolling deformation is beneficial to ensuring that a uniform structure is formed after subsequent heating treatment.

Further, in the step (4), the process conditions of the high-temperature heat treatment are as follows: after cold rolling deformation, annealing treatment is carried out at 850-1000 ℃, and the heat preservation time is 60-120 minutes; after annealing, water quenching is adopted for rapid cooling. The purpose of the high temperature hold is to form coarse recrystallized grains, so that the broken spherical carbides are transferred from the grain boundaries to the interior of the coarse recrystallized grains, thereby reducing the grain boundary corrosion tendency.

The invention principle is as follows: after the stainless steel is irradiated, a radiation-induced segregation (RIS) effect is generated, so that a chromium-poor phenomenon occurs on grain boundaries, the corrosion of the grain boundaries is poor, and stress cracking corrosion easily occurs. Zirconium and hafnium are elements with large size radius, which can effectively reduce or inhibit radiation-assisted stress corrosion cracking (IASCC), and promote defect recombination mainly through a solid solution-vacancy capture mechanism. Specifically, a strong carbide forming element Hf is added into the alloy to form a high-stability spherical particle HfC compound, so that the solid solution content of actual C in austenite particles is greatly reduced, and the corrosion resistance of the stainless steel is improved; meanwhile, titanium and zirconium are both strong carbide forming elements, and by adding titanium and zirconium into the stainless steel, carbon is combined with the titanium and the zirconium to generate TiC and ZrC, so that the carbon is not combined with chromium, and crystal boundary chromium deficiency is not caused, thereby avoiding intergranular corrosion and further improving the corrosion resistance of the stainless steel; in addition, the addition of titanium and zirconium in stainless steel can change the inclusion form and distribution in the steel, and has a certain positive effect on the mechanical properties of austenitic stainless steel.

Is advantageous inThe effect is as follows: compared with the prior art, the invention has the advantages that: (1) according to the invention, zirconium, hafnium and titanium are added into the stainless steel, so that not only can the strength be improved, but also the irradiation resistance of the austenitic stainless steel can be improved, and finally, the hafnium, zirconium and titanium reinforced austenitic stainless steel with good corrosion resistance and excellent mechanical property is obtained; 0.5mol/L H at 80 DEG C₂SO₄In the electrolyte, the corrosion rate of the austenitic stainless steel is 20.3-32.7 muA/cm²Moreover, the plasticity of the austenitic stainless steel is higher than 49%, and the tensile strength is higher than 730 MPa; (2) the preparation method of the austenitic stainless steel is simple, the process controllability is strong, and the industrial production is easy to realize.

Drawings

FIG. 1 is a graph showing the mechanical properties of a hafnium zirconium titanium reinforced austenitic stainless steel manufactured in example 1;

FIG. 2 is an electron microscope scanning image of the corrosion surface of the hafnium zirconium titanium reinforced austenitic stainless steel prepared in example 2 after being subjected to the corrosion resistance test;

FIG. 3 is a polarization diagram of the hafnium zirconium titanium reinforced austenitic stainless steel prepared in example 3 during a corrosion resistance test.

Detailed Description

The technical scheme of the invention is further explained by combining the attached drawings.

The invention relates to a hafnium zirconium titanium reinforced austenitic stainless steel, which is characterized in that on the basis of 304 austenitic stainless steel alloy components, strong carbide forming elements of hafnium (Hf), zirconium (Zr) and titanium (Ti) are added, and 304-TiZrHf stainless steel is used for short. The alloy comprises the following elements in percentage by mass: c is less than or equal to 0.05, Ni is 8.0-13.0, Cr is 18.0-22.0, Ti is less than or equal to 0.1, Hf is less than or equal to 0.05 and less than or equal to 0.4, Zr is less than or equal to 0.05 and less than or equal to 0.3, Mn is less than or equal to 2.0, Si is less than or equal to 1.0, P is less than or equal to 0.035, S is less than or equal to 0.030, and the balance is Fe.

304 is American grade, corresponding to Chinese stainless steel grade 06Cr₁₉Ni₁₀(ii) a 304 stainless steel is a food grade stainless steel accepted by the state, is mainly used in the aspects of food processing, storage and transportation, and also has important application in medical appliances, ship parts and the like. The performance indexes of the plate are as follows: the yield strength is more than or equal to 205MPa, the tensile strength is more than or equal to 520MPa, and the elongation rate is higher thanNot less than 40 percent and the hardness is not more than HV 200.

The 304 stainless steel contains not more than 0.08% of C. C in austenitic stainless steel has a strong solid solution strengthening effect, but C is easily combined with Fe to form cementite Fe₃C, is precipitated in a lamellar manner, so that the corrosion resistance of the stainless steel is difficult to improve. Therefore, the addition of the strong carbide forming element Hf to the alloy results in the formation of a high stability HfC compound in the form of spherical particles, which greatly reduces the actual C solid solution content in the austenite grains and improves the corrosion resistance of stainless steel.

Titanium and zirconium are both strong carbide forming elements, and when titanium and zirconium are added into stainless steel, carbon is combined with the titanium and the zirconium to generate TiC and ZrC, so that the carbon is not combined with chromium, the chromium depletion of a crystal boundary is avoided, and the intergranular corrosion is avoided. The content of chromium in the austenite grains is improved, so that the corrosion resistance of the stainless steel is increased. The titanium and zirconium added into the stainless steel can also change the inclusion form and distribution in the steel, and have a certain positive effect on the mechanical properties of the austenitic stainless steel.