CN112342352B - A kind of corrosion-resistant high manganese austenitic steel plate and preparation method thereof - Google Patents

Abstract

The invention discloses a corrosion-resistant high-manganese austenitic steel plate. The high-manganese austenitic steel has an austenite structure, the non-proportional elongation strength of the high-manganese austenitic steel is Rp0.2≥424MPa, and the tensile strength is Rm ≥613MPa, elongation after fracture A≥48%, 8h salt spray corrosion weight gain≤0.011mg/mm ² . The purpose of the present invention is to provide a method for improving the corrosion resistance of high manganese austenitic steel based on grain boundary engineering, which solves the problem of poor corrosion resistance of high manganese austenitic steel in the prior art. The invention discloses a preparation method of a corrosion-resistant high manganese austenitic steel plate, which specifically includes: step 1, forging an ingot into a slab; step 2, preheating the slab, and then performing 4 passes of rolling In step 3, the hot-rolled plate obtained in step 2 is subjected to homogenization treatment, and then cold-rolled and annealed to obtain a high-manganese steel plate; in step 4, the annealed high-manganese steel plate is deformed to obtain a final sheet.

Description

A kind of corrosion-resistant high manganese austenitic steel plate and preparation method thereof

technical field

The invention belongs to the technical field of metallurgical material preparation methods, and relates to a corrosion-resistant high-manganese austenitic steel plate. The invention also discloses a preparation method of the corrosion-resistant high-manganese austenitic steel plate.

Background technique

Stainless steel is an indispensable traditional metal material with huge consumption today, and is widely used in various fields of national economic construction and people's life. In order to obtain good corrosion resistance and oxidation resistance, Ni and Cr are often used as alloying elements in stainless steel, and their content is very high. However, as far as the world is concerned, Ni and Cr are both resource-deficient and expensive strategic metal elements; in particular, my country is one of the poor nickel-chromium countries, the reserves of nickel-chromium are very small, and the raw materials are mainly imported. The current situation has seriously hampered the development of stainless steel production in China.

In order to save Ni and Cr, especially Ni, as early as during World War II, researchers from Germany, Britain, the United States and other countries carried out the research work of replacing Ni with Mn and replacing Cr with Al in Ni-Cr stainless steel. Since the 1960s, the research and development of nickel-chromium-saving and nickel-chromium-free heat-resistant steel has always been one of the key goals of metallurgical and material workers in my country. In recent years, scientific and technical personnel from some universities and metallurgical enterprises in my country have also carried out a lot of work in the research of nickel-saving ferritic stainless steel and high nitrogen stainless steel, and have made certain progress. However, these stainless steels still have relatively high levels of Cr. Undoubtedly, how to use other resource-rich alloying elements to replace or mostly replace Ni and Cr in stainless steel, save resources and reduce costs, to produce economical nickel-chromium-free stainless steel or nickel-free low-chromium stainless steel, is a far-reaching task. meaningful strategic research topics.

According to the research and design ideas of replacing Ni with Mn and replacing Cr with Al, researchers have long noticed that Fe-Mn-Al-C austenitic alloys have the potential to replace or partially replace austenitic stainless steel. However, studies have found that although this type of austenitic Fe-Mn-Al-C alloy has strong oxidation resistance, the problem it faces is poor corrosion resistance.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for improving the corrosion resistance of high manganese austenitic steel based on grain boundary engineering, which solves the problem of poor corrosion resistance of high manganese austenitic steel in the prior art.

The technical scheme adopted in the present invention is a corrosion-resistant high-manganese austenitic steel sheet, the structure of the high-manganese austenitic steel is austenite, and the non-proportional elongation strength of the high-manganese austenitic steel is Rp0.2≥424MPa , tensile strength Rm≥613MPa, elongation after fracture A≥48%, 8h salt spray corrosion weight gain≤0.011mg/mm ² .

The second technical solution adopted in the present invention is, a preparation method of a corrosion-resistant high-manganese austenitic steel plate, the prepared high-manganese austenitic steel is as above, and is specifically implemented according to the following steps:

Step 1, heating the ingot to 1200±50°C, keeping the temperature for 2±0.5h, and then naturally cooling, and forging into a slab;

Step 2, preheating the slab, and then performing 4 passes of rolling, the starting rolling temperature is 1100-1050 °C, and the final rolling temperature is more than 1000 °C, to obtain a hot-rolled sheet;

In step 3, the hot-rolled sheet obtained in step 2 is kept at 1000-1100° C. for 1±0.5 h for homogenization treatment, and then cold-rolled and annealed to obtain a high-manganese steel sheet;

In step 4, the annealed high manganese steel sheet is deformed by 2% to 30% to obtain a final sheet.

The second technical solution of the present invention is also characterized in that:

In step 2, the slab is preheated, specifically: heating the slab to 1150-1200° C., and keeping the temperature for 1±0.5h.

The pass reduction ratio for 4 passes of rolling is 25% to 40%.

The reduction rate of the first pass is (25±0.5)%, the reduction rate of the second pass is (38±0.5)%, the reduction rate of the third pass is (37±0.5)%, and the reduction rate of the fourth pass is 40 %.

After 4 passes of rolling, the thickness of the hot-rolled sheet is 6±0.3mm.

The specific parameters for cold rolling in step 3 are: total reduction ratio of cold rolling > 80%, rolling to a thickness of 1±0.1 mm.

The annealing process in step 3 is as follows: heat preservation at 750-850° C. for 15-25 minutes.

In step 4, the annealed high manganese steel sheet is deformed by 10% to 20% to obtain the final sheet.

The beneficial effects of the present invention are:

In the present invention, the strength and plasticity requirements of stainless steel are considered, combined with the idea of cost saving, and a reasonable deformation heat treatment process is adopted to obtain an ideal microstructure, ensure its mechanical property requirements, and improve its corrosion resistance at the same time. The method of the present invention can obtain High manganese austenitic steel plate with certain corrosion resistance, which greatly reduces the cost of stainless steel.

Description of drawings

1 is a secondary electron image in Example 1 of a method for preparing a corrosion-resistant high manganese austenitic steel sheet of the present invention;

2 is a secondary electron image in Example 2 of a method for preparing a corrosion-resistant high manganese austenitic steel sheet according to the present invention;

3 is a secondary electron image in Example 3 of a method for preparing a corrosion-resistant high manganese austenitic steel sheet according to the present invention;

4 is a secondary electron image in Example 4 of a method for preparing a corrosion-resistant high manganese austenitic steel sheet of the present invention.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The invention is a corrosion-resistant high-manganese austenitic steel plate, the structure of which is austenite, the non-proportional elongation strength of the high-manganese austenitic steel is Rp0. ≥48%, 8h salt spray corrosion weight gain ≤0.011mg/mm ² .

A preparation method of a corrosion-resistant high-manganese austenitic steel plate of the present invention, the prepared high-manganese austenitic steel is as above, and is specifically implemented according to the following steps:

Step 1, heating the ingot to 1200±50℃, then keeping the temperature for 2±0.5h, then cooling naturally, and forging into a slab;

In step 2, the slab is heated to 1150-1200°C, kept for 1±0.5h for preheating, and then rolled for 4 passes. 25% to 40% to obtain a hot-rolled sheet; specifically: the reduction ratio of the first pass is (25±0.5)%, the reduction ratio of the second pass is (38±0.5)%, and the reduction ratio of the third pass ( 37±0.5)%, the 4th pass reduction rate is 40%, and the thickness of the hot-rolled sheet after 4 passes of rolling is 6±0.3mm;

In step 3, the hot-rolled sheet obtained in step 2 is kept at 1000-1100° C. for 1±0.5 h for homogenization treatment, and then cold-rolled and annealed to obtain a high-manganese steel sheet. To 1±0.1mm thick, the annealing process is: heat preservation at 750～850℃ for 15～25min;

In step 4, the annealed high-manganese steel sheet is deformed by 2% to 30% to obtain the final sheet. Preferably, in step 4, the annealed high-manganese steel sheet is deformed by 10% to 20% to obtain the final sheet.

In the embodiment of the present invention, the microstructure of the high manganese austenitic steel plate after deformation heat treatment is observed by using a field emission electron probe JEOL JXA-8530F; room temperature stretching is carried out on a CMT5105-SANS microcomputer-controlled electronic universal testing machine; The experiment was carried out in LYW-025 salt spray test box, the mass concentration of NaCl solution was (5.0±1)%, the pH value range was 6.5～7.2, the temperature in the salt spray box was kept within the range of (35±2)℃, and the humidity was within the range of (35±2)℃. Controlled at (45±2)%Rh.

The room temperature tensile specimen is made into standard tensile specimen with rectangular section according to GB/T228-2002 "Room temperature tensile test method for metal materials"; the neutral salt spray test (NSS test) is carried out according to the standard GJB150.11A-2009.

Examples 1-4

The present invention provides a set of experimental results as examples. The composition of the steel is the same, the steelmaking, continuous casting, forging billet heating and rolling processes are the same, and the solution treatment process after cold rolling is the same. In terms of the control system of deformation, some deformation, performance test results and secondary electron image structure are given as comparative examples.

A preparation method of a corrosion-resistant high-manganese austenitic steel plate is specifically implemented according to the following steps:

Step 1, heating the ingot to 1200°C, holding the temperature for 2h, then cooling naturally, and forging into a slab;

In step 2, the slab is heated to 1200°C, held for 1 hour for preheating, and then rolled for 4 passes, with an opening temperature of 1050°C and a final rolling temperature of over 1000°C; the first pass reduction rate is 25.7%, the second pass The reduction ratio of the second pass is 38.5%, the reduction ratio of the third pass is 37.5%, and the reduction ratio of the fourth pass is 40%. At this time, the total reduction ratio is 83%, and the thickness of the obtained hot-rolled sheet is 6 mm;

Step 3, the hot-rolled sheet is kept at 1100° C. for 1 hour, subjected to homogenization treatment, and then cold-rolled and annealed. The total reduction ratio of cold-rolling is 80%, and rolled to a thickness of 1 mm. The annealing process is: keep at 850° C. for 25 minutes;

Step 4, deformation treatment process: the steel plate obtained in step 3 is stretched and deformed by 2% to 30% at room temperature to obtain the final plate; the specific processes are respectively adopted in the following 4 types: 2% (Example 1), 10% (Example 2) ), 20% (Example 3), 30% (Example 4).

The secondary electron images obtained in Examples 1-4 are shown in Figures 1-4, which are austenite structures, and with the increase of deformation, the substructure becomes more complex, and the proportion of special grain boundaries increases.

The mechanical properties and corrosion resistance test results are shown in Table 1:

Table 1

It can be seen from the results of the process comparison research in the above-mentioned embodiments that the deformation treatment process system for obtaining a high manganese austenitic steel plate with optimal mechanical properties and corrosion resistance is: deformation 10% to 20%, and the current The results are: room temperature tensile elongation strength Rp0.2≥424MPa, tensile strength Rm≥613MPa, elongation after fracture A≥48%, 8h salt spray corrosion weight gain≤0.011mg/mm ² .

Example 5

The preparation method of a corrosion-resistant high-manganese austenitic steel plate of the present invention is specifically implemented according to the following steps:

Step 1, heating the ingot to 1250°C, keeping the temperature for 2.5h, then cooling naturally, and forging into a slab;

In step 2, the slab is heated to 1200°C, held for 1.5h for preheating, and then rolled for 4 passes, the starting rolling temperature is 1100°C, the final rolling temperature is above 1000°C, and the first pass reduction rate is 25.7%. The reduction rate of the 2nd pass is 38.5%, the reduction rate of the 3rd pass is 37.5%, and the reduction rate of the 4th pass is 40% to obtain a hot-rolled sheet; after 4 passes of rolling, the thickness of the hot-rolled sheet is 6±0.3mm;

In step 3, the hot-rolled sheet obtained in step 2 is kept at 1100° C. for 1.5 hours for homogenization treatment, and then cold-rolled and annealed to obtain a high-manganese steel sheet. mm thick, the annealing process is: heat preservation at 850°C for 25min;

In step 4, the annealed high manganese steel sheet is deformed by 30% to obtain a final sheet.

Example 6

A preparation method of a corrosion-resistant high-manganese austenitic steel plate of the present invention, the prepared high-manganese austenitic steel is as above, and is specifically implemented according to the following steps:

Step 1, heating the ingot to 1150°C, then keeping the temperature for 1.5h, then cooling naturally, and forging into a slab;

In step 2, the slab is heated to 1150°C, kept for 0.5h for preheating, and then rolled for 4 passes, the starting rolling temperature is 1050°C, the final rolling temperature is above 1000°C, and the first pass reduction rate is 25.7%. The reduction rate of the 2nd pass is 38.5%, the reduction rate of the 3rd pass is 37.5%, and the reduction rate of the 4th pass is 40% to obtain a hot-rolled sheet; after 4 passes of rolling, the thickness of the hot-rolled sheet is 6±0.3mm;

In step 3, the hot-rolled sheet obtained in step 2 is kept at 1000° C. for 0.5 h for homogenization treatment, and then cold-rolled and annealed to obtain a high-manganese steel sheet. mm thick, the annealing process is: heat preservation at 750°C for 15min;

In step 4, the annealed high manganese steel sheet is deformed by 2% to obtain a final sheet.

What the present invention obtains is the high manganese austenitic steel sheet with improved corrosion resistance after deformation heat treatment, and the basis of the rolling and deformation heat treatment process adopted in the present invention is:

The hot rolling process adopts multi-pass large deformation rolling in the high temperature recrystallization zone, and the austenite grains are fully refined through dynamic recrystallization. Due to the characteristics of high manganese steel, the distribution of elements after hot rolling is uneven, and the After rolling, a solution treatment scheme with a temperature of 1100 °C for 1 h was adopted for homogenization treatment.

The solution treatment after cold rolling is to obtain uniform and refined austenite grains through the recrystallization process of the steel plate after rolling deformation, so as to obtain the required strength and toughness.

Starting from grain boundary engineering, improving the corrosion resistance of low stacking fault energy face-centered cubic structure alloys is mainly achieved through deformation and heat treatment. By controlling the deformation and annealing process parameters, not only a high proportion of CSL grain boundaries can be obtained, but also a high The proportion of recrystallized trigeminal grain boundaries plays a significant role in improving the corrosion resistance of alloys with a face-centered cubic structure.

By adopting the method of the present invention, a high manganese austenitic steel plate with certain corrosion resistance can be obtained, which greatly reduces the cost of stainless steel.

The invention meets the requirements of mechanical properties through an appropriate deformation heat treatment method, and has certain corrosion resistance at the same time, which will effectively widen the application range of the high manganese austenitic steel. The steel plate provided by the present invention can be applied to occasions where the corrosion resistance requirement is not particularly high, such as door and window handles, stair guardrails, fences, as well as construction auxiliary materials and furniture decorations in non-coastal areas.

Claims (3)

1. The preparation method of the corrosion-resistant high-manganese austenitic steel plate is characterized by comprising the following steps:

step 1, heating the cast ingot to 1200 +/-50 ℃, preserving heat for 2 +/-0.5 h, then naturally cooling and forging into a plate blank;

step 2, preheating the plate blank, and then carrying out 4-pass rolling at the initial rolling temperature of 1100-1050 ℃ and the final rolling temperature of over 1000 ℃ to obtain a hot rolled plate;

step 3, carrying out homogenization treatment on the hot rolled plate obtained in the step 2 at the temperature of 1000-1100 ℃ for 1 +/-0.5 h, and then carrying out cold rolling and annealing to obtain a high manganese steel plate;

step 4, deforming the annealed high manganese steel plate by 10-20% to obtain a final plate;

the pass reduction rate of 4-pass rolling in the step 2 is 25.7% -40%; wherein the first pass reduction rate is 25.7%, the 2 nd pass reduction rate is 38.5%, the 3 rd pass reduction rate is 37.5%, and the 4 th pass reduction rate is 40%;

the specific parameters for cold rolling in the step 3 are as follows: the total rolling reduction rate of cold rolling is more than 80 percent, and the thickness of the rolled steel is 1 plus or minus 0.1 mm;

the annealing process in the step 3 comprises the following steps: preserving the heat for 15-25 min at 750-850 ℃;

the structure of the high-manganese austenitic steel is austenite, the non-proportional elongation strength Rp0.2 of the high-manganese austenitic steel is more than or equal to 424MPa, the tensile strength Rm is more than or equal to 613MPa, the elongation A after fracture is more than or equal to 48 percent, and the 8h salt spray corrosion weight gain is less than or equal to 0.011mg/mm²。

2. The method for preparing a corrosion-resistant austenitic steel sheet with high manganese content according to claim 1, wherein the slab is preheated in step 2, specifically: and heating the plate blank to 1150-1200 ℃, and preserving heat for 1 +/-0.5 h.

3. The method of claim 1, wherein the hot-rolled sheet thickness after 4 passes of rolling is 6 ± 0.3 mm.

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