Oxide dispersion strengthened (ODS) steel preparing method and martensitic steel

A martensitic steel and dispersion strengthening technology, applied in the preparation of oxide dispersion strengthened steel, ODS low activity martensitic steel, martensitic steel field, can solve the problems of long process flow, high manufacturing cost, and prominent material heterogeneity and other problems, to achieve the effect of short process flow and low manufacturing cost

Active Publication Date: 2016-01-27

UNIV OF SCI & TECH BEIJING

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Problems solved by technology

[0003] There are the following main problems in the preparation of ODS steel by mechanical alloying: first, limited by the mechanical alloying process, the output of a sin...

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Abstract

The invention provides an oxide dispersion strengthened (ODS) steel preparing method and martensitic steel. The oxide dispersion strengthened steel preparing method includes the steps that iron oxides are added into a casting mould, a proper number of rare earth elements are added into a fully deoxidized molten steel, the mixture is rapidly cast into the casting mould, and the ODS steel is obtained through the reaction between the rare earth elements and the iron oxides. The martensitic steel is obtained by performing hot forging, hot rolling, hot machining and hot treatment on the ODS steel prepared through the method. The ODS steel prepared through the method is high in hardenability, the residual austenitic content is very low, and a full martensite structure can be obtained. W, V and Ta are strong carbide forming elements and have a remarkable strengthening effect, and the mechanical property is obviously higher than that of steel prepared through a traditional smelting technology. Meanwhile, the ductile-brittle transition temperature (DBTT) value is minus 80 DEG C and minus 90 DEG C, the good toughness of the traditional smelting technology is well inherited, and meanwhile good anti-radiation performance is achieved. By means of the ODS steel preparing method, the demands for preparing ODS steel in batches with stability, short process and low cost can be met.

Technology Topic

Rare-earth elementIron oxide +15

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Examples

Experimental program(3)

Example Embodiment

[0039] The present invention is a preparation method of ODS steel. The basic principle is based on the strong binding energy between rare earth element RE and O. Its standard molar formation enthalpy is higher than the formation enthalpy of oxides of other alloying elements, and it is very easy to form stable rare earth oxidation. Through the timing of adding rare earth elements and the way of introducing oxygen, the rare earth elements combine with oxygen to form fine oxide particles. For example, adding an appropriate amount of iron oxide to the mold, adding an appropriate amount of rare earth element yttrium to the fully deoxidized molten steel and casting quickly, the yttrium in the molten steel takes the oxygen in the iron oxide to form yttrium oxide, which is dispersed in the molten steel. By controlling the oxygen content in the molten steel and the added amount of rare earth elements, smelted ODS steel with evenly dispersed rare earth oxides is obtained. The rare earth element in the present invention is metal yttrium. The specific preparation method steps are as follows:

[0040] Steelmaking using vacuum induction/magnetic stirring technology, the melting temperature is 100-200℃ above the melting point of iron;

[0041] 1. Add iron oxide to the mold, the iron oxide is Fe 2 O 3

[0042] 2. Put industrial pure iron and others into the crucible, and power on when the vacuum reaches 10Pa; start refining after the vacuum is less than 7Pa;

[0043] 3. In the smelting process, the deoxidation depth is controlled by the burning loss of the deoxidizing element Al, when the oxygen concentration [O] <10 -5 When adding alloying elements for alloying;

[0044] 4. After the alloying process is over, add the rare earth element yttrium to the molten steel, the Y and Fe 2 O 3 The ratio of the amount of the material is 1:1-1.2:1. After stirring, quickly cast the molten steel into the mold. The casting temperature depends on the fluidity of the molten steel. While ensuring the fluidity, reduce the temperature of the molten steel as much as possible;

[0045] 5. Hot forging and hot rolling of cast ingots (ODS steel);

[0046] 6. Carry out heat treatment on the hot-worked slab to obtain a single-phase martensitic structure, namely martensitic steel.

[0047] According to the above preparation method, vacuum induction melting and casting of steel ingots are carried out. In order to obtain the mechanical properties of steel, controlled rolling and controlled cooling of the steel ingots and optimization of the heat treatment process are carried out. The controlled cooling process is as follows: the starting rolling temperature is 1100-1050℃, the final rolling temperature is controlled at about 850-950℃, and it is adopted after rolling. On-line spray cooling, the heat treatment process is: quenching and high temperature tempering, in which the quenching temperature is 850-1100℃, the tempering temperature is 710-800℃, and the tempering time is 90min-120min.

Example Embodiment

[0048] Example 1:

[0049] A kind of ODS martensitic steel prepared based on the above method, and its various components account for the percentage of total mass:

[0050] C: 0.09%, Cr: 8.9%, Mn: 0.51%, W: 2.09%, N: 0.055%, Ta: 0.12%, Ti: 0.45%, Si: 0.13%, V: 0.045%, Y: 0.07%, B <0.001%, S <0.003%, P <0.005%, Fe margin, Fe in the mold 2 O 3 :0.14%; finished products are made through the following steps:

[0051] (a) According to S1-S4 in the preparation method of the present invention, vacuum smelting prepares steel ingots or continuous casting steel bars, with the following components in percentage of the total mass:

[0052] C: 0.09%, Cr: 8.9%, Mn: 0.51%, W: 2.09%, N: 0.055%, Ta: 0.12%, Ti: 0.45%, Si: 0.13%, V: 0.045%, Y: 0.07%, B <0.001%, S <0.003%, P <0.005%, Fe margin; Fe in the mold 2 O 3 : 0.14%.

[0053] (b) Perform the first thermal deformation through forging or rolling of steel ingots or continuously cast steel bars to obtain semi-finished products;

[0054] (c) Heating the semi-finished product to 1150°C to austenitize, and deform it again by hot rolling until the required shape and size are obtained;

[0055] (d) Cool the product to below 50°C, and then make the product into a sample. And numbered 950-1 to 950-6;

[0056] (e) Heat all the samples to the temperature range of 950℃ at the same time for a time period of 15 minutes for austenitizing heat treatment;

[0057] (f) Cool the sample in water to below 50°C, and then heat the samples with different numbers to the temperature range of 720°C, 750°C, and 780°C, respectively, and keep them for a time period of 20 and 120 minutes for tempering heat treatment. The specific numbers and corresponding processes are listed in the table below.

[0058] The examples in the following table collectively embody the heat treatment process and characteristics of the present invention. The percentage of its ingredients to the total mass is:

[0059] C: 0.09%, Cr: 8.9%, Mn: 0.51%, W: 2.09%, N: 0.055%, Ta: 0.12%, Ti: 0.45%, Si: 0.13%, V: 0.045%, Y: 0.07%, B <0.001%, S <0.003%, P <0.005%, Fe margin, Fe2O3 in the mold: 0.14%;

[0060]

[0061]

Example Embodiment

[0062] Example 2:

[0063] A kind of ODS martensitic steel prepared based on the above method, and its various components account for the percentage of total mass:

[0064] C: 0.09%, Cr: 9.3%, Mn: 0.55%, W: 2.5%, N: 0.06%, Ta: 0.19%, Ti: 0.53%, Si: 0.13%, V: 0.045%, Y: 0.2%, B <0.001%, S <0.003%, P <0.005%, Fe margin, Fe in the mold 2 O 3 : 0.4%; finished products are made through the following steps:

[0065] (a) According to S1-S4 in the preparation method of the present invention, vacuum smelting prepares steel ingots or continuous casting steel bars, with the following components in percentage of the total mass:

[0066] C: 0.09%, Cr: 9.3%, Mn: 0.55%, W: 2.5%, N: 0.06%, Ta: 0.19%, Ti: 0.53%, Si: 0.13%, V: 0.045%, Y: 0.2%, B <0.001%, S <0.003%, P <0.005%, Fe margin, Fe in the mold 2 O 3 : 0.4%.

[0067] (b) Perform the first thermal deformation through forging or rolling of steel ingots or continuously cast steel bars to obtain semi-finished products;

[0068] (c) Heating the semi-finished product to 1200°C to austenitize, and deform it again by hot rolling until the required shape and size are obtained;

[0069] (d) Cool the product to below 50°C, and then make the product into a sample. They are numbered 1000-5 to 1000-6 and 1050-7 to 1050-8 respectively;

[0070] (e) Then heat the sample to 1000°C and 1050°C for a time period of 20 minutes for austenitizing heat treatment;

[0071] (f) Cool the sample in water to below 50°C, and then heat the samples with different numbers to 720°C and 780°C temperature range respectively and keep them for a time period of 20 and 120 minutes for tempering heat treatment. The specific numbers and corresponding processes are listed in the above table.

[0072] The following table shows the comparison of the mechanical properties of specific examples 1 and 2 of the present invention.

[0073]

[0074] It can be seen from the table that the mechanical properties of ODSRAFM steel prepared by this process are significantly higher than that of steel prepared by traditional melting process. At the same time, the ductile-brittle transition temperature DBTT50 is -80℃ and -90℃, which also inherits the good toughness of the traditional smelting process. From Figure 9-10 It can be seen that there is no helium bubble aggregation before and after irradiation at 475°C and 200dpa, indicating that the material has excellent radiation resistance.

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Classification and recommendation of technical efficacy words

Low manufacturing cost
Short process

Oxide dispersion strengthened (ODS) steel preparing method and martensitic steel

AI-Extracted Technical Summary

Problems solved by technology

Abstract

Image

Examples

Example Embodiment

Example Embodiment

Example Embodiment

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Description & Claims & Application Information

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