CN106435380A - Microalloyed high-aluminum high-ductility steel plate and manufacturing method thereof - Google Patents

Abstract

The invention relates to a micro-alloyed high-aluminum high-plasticity steel plate and a preparation method thereof, belonging to the field of alloy steel. The chemical composition mass percentage of the steel plate of the present invention is: C: 0.8%~1.0%, Mn: 28%~30%, Al: 8.0%~10%, Nb: 0.02~0.10%, V: 0.02~0.10%, Ti: 0.02~0.10%, N: 0.02~0.08%, P<0.003%, S<0.003%, the balance is Fe and unavoidable impurities. The method of the present invention firstly prepares raw materials according to the chemical composition, then forges the slab into a slab after smelting and casting, heats the slab, and performs multi-pass hot rolling deformation after homogenization treatment, and the cumulative deformation is 85% to 90%. Water cooling after rolling, air cooling to room temperature; solution treatment of the hot-rolled steel plate, rapid heating to the solution temperature, heat preservation for a period of time, and water quenching to room temperature; pickling of the solution treated steel plate, cold rolling, after Multi-pass rolling deformation, the cumulative compression is 65%~80%; the cold-rolled steel plate is subjected to final annealing treatment, and then water-quenched to room temperature to obtain a micro-alloyed high-alumina high-plasticity steel plate. The strength and plasticity of the steel plate prepared by the invention can reach 50GPa·%, which obviously improves the impact and collision resistance of the material.

Description

A kind of micro-alloyed high-aluminum high-plasticity steel plate and preparation method thereof

technical field

The invention belongs to the field of alloy steel, in particular to a micro-alloyed high-aluminum high-plasticity steel plate and a preparation method thereof.

Background technique

With the rapid development of the automobile industry and the continuous improvement of human awareness of environmental protection and energy conservation, metal materials for automobiles are developing towards the two main goals of energy conservation and safety. For this reason, on the one hand, the specific strength of metal materials should be improved to reduce the weight of the vehicle body and fuel consumption, which is conducive to saving energy and reducing environmental pressure; on the other hand, the collision absorption capacity of metal materials should be improved to convert most of the collision energy into The plastic deformation of the material of the reasonable part of the body ensures the safety of the driver.

Chinese invention patent CN103667883A discloses a low-density, high-strength and high-toughness automobile steel plate and its preparation process, which is characterized in that its composition and mass fraction are composed of the following: C: 0.60%~0.70%, Si: 0.30%~0.40%, Mn : 10.0%~15.0%, Al: 5.0%~10.0%, P<0.005%, S<0.003%, the balance is Fe and unavoidable impurities. The tensile strength of this steel is 905MPa, the elongation after fracture is 42%, the strength-plastic product is 38%, and the tensile strength is low, which cannot meet the requirements of ultra-high-strength steel. Chinese invention patent CN104694816A discloses a method for preparing a high-Al medium-manganese steel with a strength-plasticity product greater than 30GPa·%. Mn, 4.0%~7.5%Al, P<0.003%, S<0.002%, the balance is Fe and unavoidable impurities. The elongation rate of this kind of steel after fracture is good, reaching about 45%, but its tensile strength is a bit low, and its comprehensive mechanical properties are not very good, all around 800MPa, which may not meet the requirements of some automobiles for ultra-high-strength steel.

Contents of the invention

The purpose of the present invention is to provide a micro-alloyed high-aluminum high-plasticity steel plate, the chemical composition and mass percentage of the steel plate are: C: 0.8%~1.0%, Mn: 28%~30%, Al: 8.0%~10% %, Nb: 0.02~0.10%, V: 0.02~0.10%, Ti: 0.02~0.10%, N: 0.02~0.08%, P<0.003%, S<0.003%, and the balance is Fe and unavoidable impurities.

Another object of the present invention is to provide a method for preparing the microalloyed high-alumina high-plasticity steel plate, which specifically includes the following steps:

(1) Forging into slabs after smelting and casting;

(2) Hot rolling: heat the slab, and perform multi-pass hot rolling deformation after homogenization treatment, the cumulative deformation is 85%~90%, water cooling after rolling, and air cooling to room temperature;

(3) Solution treatment: The hot-rolled steel plate is subjected to solution treatment, heated rapidly to the solution temperature for a period of time, and then water quenched to room temperature;

(4) Cold rolling: the steel plate after solution treatment is pickled and then cold-rolled. After multi-pass rolling deformation, the cumulative compression is 65%~80%;

(5) Annealing treatment: The cold-rolled steel plate is subjected to final annealing treatment, and then water-quenched to room temperature to obtain a micro-alloyed high-alumina high-plasticity steel plate.

Preferably, the billet heating temperature in step (2) of the present invention is 1150-1200°C, the holding time is 1-2h, the starting rolling temperature is 1100-1150°C, the finishing rolling temperature is 850-900°C, and the coiling temperature is 400-500°C.

Preferably, the solution treatment temperature of the billet in step (3) of the present invention is 950-1100° C., and the holding time is 0.5-2 hours.

Preferably, the annealing temperature in step (5) of the present invention is 900-1050° C., and the holding time is 15-30 minutes.

Preferably, the heating temperature of the ingot in step (1) is 1170-1200°C, the holding time is 1-2h, the starting forging temperature is 1100-1200°C, and the final forging temperature is 800-900°C; under these temperature conditions, the steel performance is the best. After casting, defects such as shrinkage cavities and porosity affect the mechanical properties of the steel plate. Therefore, forging is required to eliminate defects such as shrinkage cavities and porosity, and improve the mechanical properties of the material.

In the present invention, the heating temperature of the hot-rolled billet is 1150-1200°C, the holding time is 1-2h, the starting rolling temperature is 1100-1150°C, the finishing rolling temperature is 850-900°C, and the crimping temperature is 400-500°C. Best performance. Since the final steel plate is relatively small in thickness, it must be rolled and deformed to obtain the size we need and obtain a smooth surface. The rolling is divided into two parts: hot rolling and cold rolling. The higher the temperature, the higher the strength of the material. Reduced, plasticity increased, that is, the ability to resist deformation is reduced, and the requirements for the rolling force of the rolling mill are reduced, so it is hot-rolled and deformed first, and finally cold-rolled and deformed. Due to work hardening, high-strength steel plates can be obtained , and then annealing it to obtain the high-toughness steel plate we need.

The solid solution treatment temperature of the billet is 950-1100°C, and the holding time is 0.5-2h. After hot rolling and deformation, alloy carbides are precipitated during hot deformation and cooling, which is not conducive to subsequent processing. Therefore, solid solution treatment is required to fully dissolve various phases and carbides in the alloy and eliminate stress. And softening, improving the plasticity and toughness of the alloy for subsequent processing or forming.

The annealing temperature of the billet is 900-1050° C., and the holding time is 15-30 minutes. After annealed cold-rolled steel plate, the deformed grains are more uniform and finer after recrystallization, the elongation rate of the steel plate after fracture is significantly increased, and the anisotropy of the material is eliminated, and the comprehensive mechanical properties (strength and plastic product) of the material are more excellent.

The invention adds Nb, V and Ti microalloy elements to high manganese, high aluminum and high carbon steels for strengthening, while significantly increasing the yield strength and tensile strength, and at the same time ensuring that the elongation after fracture is slightly reduced or not reduced, so as to ensure the steel plate The comprehensive mechanical properties have been greatly improved to meet the needs of ultra-high-strength and high-plasticity steel plates for contemporary high-speed development of automobiles.

The present invention has the following advantages:

(1) Lower requirements on equipment: the present invention can adopt conventional hot rolling equipment and meet the production conditions. The slab heating temperature is low, which saves energy; the final rolling temperature is high, and the required rolling force is low, which can also reduce energy consumption.

(2) Good mechanical properties of the steel plate: the steel plate produced by the present invention has excellent comprehensive mechanical properties (high strength and high plasticity). After the annealing treatment of the present invention, the steel plate has a good combination of strength and plasticity, and has good impact absorption performance.

(3) Obvious weight reduction effect: Compared with DP steel, TRIP steel and other automotive structural steels, the present invention adopts a reasonable ratio of alloying elements and adds light elements such as Al. On the basis of ensuring the excellent mechanical properties of the steel plate, The density of the steel plate is reduced, and the effect of weight reduction is obvious.

(4) Broad application prospects: the high-aluminum high-plasticity steel plate described in the present invention meets the requirements of the third-generation advanced high-strength steel, and is a new type of material currently required by the automobile industry. The prepared material can be used in the automobile manufacturing industry, as well as Widely used in oil pipelines, railway transportation, engineering machinery, aircraft carriers and other industries.

The present invention carries out fine-grain strengthening and precipitation strengthening through Nb, V and Ti micro-alloying to increase its strength, and the reduction of plasticity is not obvious or does not decrease, and finally the high-quality steel with stable performance, good toughness and excellent anti-collision performance can be obtained. Tough steel plate; it has a tensile strength of 1100~1250MPa, an elongation of 40~50%, and a strong plastic product of about 50GPa·%. Its density is 6.7~7.0 g/cm ³ , and its weight reduction effect can reach 11%~ 15%.

Description of drawings

Fig. 1 is a process flow diagram of the present invention.

Fig. 2 is a schematic diagram of the thermal processing process of the high-aluminum high-plasticity steel plate of the present invention.

Fig. 3 is the XRD spectrum of the steel plate sample after solid solution treatment in Example 1 of the present invention.

Fig. 4 is the tensile fracture morphology of the steel plate of Example 1 in the present invention.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the content described.

Example 1

The chemical composition and mass percentage of the micro-alloyed high-aluminum high-plasticity steel plate described in this example are: C: 0.88%, Mn: 28.8%, Al: 8.5%, Nb: 0.045%, V: 0.05%, Ti: 0.05% , N: 0.06%, P<0.003%, S<0.003%, the balance is Fe and unavoidable impurities.

The preparation method of the micro-alloyed high-aluminum high-plasticity steel plate described in this embodiment specifically includes the following steps:

(1) Forging into slabs after smelting and casting: melt the prepared raw materials in a vacuum induction melting furnace at a smelting temperature of 1650°C, and pour them into ingots, forge and deform the ingots, and finally forge them into slabs. The cumulative deformation is 70%, and after forging, it is air-cooled to room temperature. The ingot heating temperature is 1180°C, the holding time is 1.5h, the starting forging temperature is 1150°C, and the final forging temperature is 850°C.

(2) Hot rolling: heat the slab to 1200°C, keep it warm for 2 hours, the thickness of hot rolling is 4mm, the starting temperature of hot rolling is 1150°C, the final rolling temperature is 870°C, 6 passes of rolling, and the curling temperature is 400°C ℃, water cooling after rolling, and air cooling to room temperature; the cumulative deformation is 85%.

(3) Solution treatment: The hot-rolled steel plate is subjected to solution treatment, rapidly heated to 1000° C. for 1 hour, and then water-quenched to room temperature.

(4) Cold rolling: the solution-treated steel plate is pickled and then cold-rolled. After 8 passes of rolling deformation, the cumulative compression is 70%;

(5) Annealing treatment: Heat the cold-rolled steel plate to 1000°C, hold it for 30 minutes for final annealing treatment, and then water quench to room temperature to obtain a micro-alloyed high-alumina high-plasticity steel plate. The final heat-treated steel plate is tested according to the national standard. Mechanical properties, the tensile strength is 850MPa, the elongation is 45%, and the strong-plastic product is as high as 38.3GPa·%.

The XRD spectrum of the steel plate sample prepared in step (3) of this example is shown in Figure 3. It can be seen from the figure that the experimental steel plate has a single austenite structure in the forged state and solution treatment at different temperatures, that is, the sample No phase transformation occurred during this heat treatment. The tensile fracture morphology of the steel plate is shown in Figure 4. It can be seen from the figure that the fracture microstructure of the sample presents many small, equiaxed dimple structures, and the dimples of the fracture are very deep, indicating that the sample is Very plastic.

Example 2

The chemical composition and mass percentage of the microalloyed high aluminum high plasticity steel plate described in this example are: C: 0.8%, Mn: 30%, Al: 9%, Nb: 0.02%, V: 0.10%, Ti: 0.10% , N: 0.02%, P<0.003%, S<0.003%, the balance is Fe and unavoidable impurities.

The preparation method of the micro-alloyed high-aluminum high-plasticity steel plate described in this embodiment specifically includes the following steps:

(1) Forging into slabs after smelting and casting: melt the prepared raw materials in a vacuum induction melting furnace at a smelting temperature of 1650°C, and pour them into ingots, forge and deform the ingots, and finally forge them into slabs. The accumulative deformation is 75%, air-cooled to room temperature after forging, in which the heating temperature of the ingot is 1200°C, the holding time is 2h, the starting forging temperature is 1100°C, and the final forging temperature is 800~900°C.

(2) Hot rolling: heat the slab to 1200°C, keep it warm for 2 hours, hot rolling thickness is 4mm, the hot rolling start temperature is 1100°C, the final rolling temperature is 850°C, 8 passes rolling, and the curling temperature is 450°C ℃, water cooling after rolling, and air cooling to room temperature; the cumulative deformation is 87%.

(3) Solution treatment: The hot-rolled steel plate is subjected to solution treatment, rapidly heated to 950°C for 0.5h, and then water-quenched to room temperature.

(4) Cold rolling: the steel plate after solution treatment is pickled and then cold-rolled. After 6 passes of rolling deformation, the cumulative compression is 65%;

(5) Annealing treatment: heat the cold-rolled steel plate to 900°C, hold it for 20 minutes for final annealing treatment, and then water quench to room temperature to obtain a micro-alloyed high-alumina high-plasticity steel plate. The final heat-treated steel plate is tested according to the national standard. Mechanical properties, the tensile strength is 1100MPa, the elongation is 45%, and the strong-plastic product is as high as 49.5GPa·%.

Example 3

The chemical composition and mass percentage of the micro-alloyed high-alumina high-plasticity steel plate described in this example are: C: 1.0%, Mn: 28%, Al: 10%, Nb: 0.10%, V: 0.02%, Ti: 0.02% , N: 0.08%, P<0.003%, S<0.003%, the balance is Fe and unavoidable impurities.

The preparation method of the micro-alloyed high-aluminum high-plasticity steel plate described in this embodiment specifically includes the following steps:

(1) Forging into slabs after smelting and casting: melt the prepared raw materials in a vacuum induction melting furnace at a smelting temperature of 1650°C, and pour them into ingots, forge and deform the ingots, and finally forge them into slabs. The cumulative deformation is 80%, and after forging, it is air-cooled to room temperature. The heating temperature of the ingot is 1170°C, the holding time is 1h, the starting forging temperature is 1200°C, and the final forging temperature is 800°C.

(2) Hot rolling: heat the slab to 1200°C, keep it warm for 2 hours, the thickness of the hot rolling is 4mm, the starting temperature of the hot rolling is 1150°C, the final rolling temperature is 900°C, rolling for 8 passes, and the curling temperature is 500°C ℃, water cooling after rolling, and air cooling to room temperature; the cumulative deformation is 90%.

(3) Solution treatment: The hot-rolled steel plate is subjected to solution treatment, rapidly heated to 1100 °C for 2 hours, and then water quenched to room temperature.

(4) Cold rolling: the solution-treated steel plate is pickled and then cold-rolled. After 8 passes of rolling deformation, the cumulative compression is 80%;

(5) Annealing treatment: Heat the cold-rolled steel plate to 1050°C, hold it for 15 minutes for final annealing treatment, and then water quench to room temperature to obtain a micro-alloyed high-alumina high-plasticity steel plate. The final heat-treated steel plate is tested according to the national standard. Mechanical properties, the tensile strength is 1080MPa, the elongation is 45%, and the strong-plastic product is as high as 48.6GPa·%.

Comparative example 1

The preparation process of the high-aluminum high-plasticity steel plate, its specific steps are as follows:

(1) Ingredients: Industrial pure iron is used as the basic raw material, electrolytic metal manganese with a purity of 99.9% and high-purity aluminum with a purity of 99.85% are used as alloy raw materials, and the chemical composition is prepared according to the mass fraction (wt%): C: 0.88%, Mn: 28.8%, Al: 8.5%, N: 0.06%, P<0.003%, S<0.003%, the balance is Fe and unavoidable impurities.

(2) Melting: The prepared raw materials are melted in a vacuum induction melting furnace at a melting temperature of 1650°C, and cast into ingots.

(3) Forging: The casting billet is forged and deformed, and finally forged into a slab with a cumulative deformation of 70%. After forging, it is air-cooled to room temperature.

(4) Hot rolling: heat the steel billet to 1200°C and keep it warm for 2 hours. According to the capacity of the experimental rolling mill, the designed hot rolling thickness is 4mm, the hot rolling start temperature is 1150°C, the final rolling temperature is 870°C, and 6 passes of rolling are carried out. , set the curling temperature to 400~500°C, and air cool to room temperature;

(5) Solution treatment: The hot-rolled steel plate is subjected to solution treatment, and the steel plate is rapidly heated to 1000° C., kept for 1 hour, and then water-quenched to room temperature.

(6) Cold rolling: pickling the steel plate after solution treatment and then cold rolling. According to the capacity of the rolling mill, after 8 passes of rolling deformation, the cumulative compression is 70%.

(7) Annealing treatment: The final annealing treatment is carried out on the cold-rolled steel plate, the steel plate is heated to 1000°C, and after holding for 0.5h, it is water-quenched to room temperature. The mechanical properties of the steel plate after the final heat treatment are tested according to the national standard. The strength is 850MPa, the elongation is 45%, and the strong plastic product is as high as 38.3GPa·%.

Comparative example 2

The difference from Comparative Example 1 is that Nb trace elements are added to the chemical composition of the raw materials, and the Nb content is 0.045%. The mechanical properties of the annealed steel plate are tested according to the national standard. The tensile strength is 950MPa and the elongation is 47%. , the strong plastic product is as high as 44.7GPa·%.

Comparative example 3

The difference from Comparative Example 1 is that Nb and V trace elements are added to the chemical composition of the raw materials, the content of which is: Nb: 0.045%, V: 0.05%, and the mechanical properties of the steel plate after the final heat treatment are tested according to the national standard. Its tensile strength is 1050MPa, elongation is 44%, and its strength and plasticity are as high as 46.2GPa·%.

Table 1 is the mechanical property of the embodiment of the present invention

It can be seen from Table 1 that the steel plate with Nb, V and Ti trace elements added alone has a proper increase in strength and a slight improvement in plasticity. The effect of a single element in the steel has its limitations. The strength and plasticity of the steel plate with three trace elements of V and Ti have been greatly improved, and as shown in Example 1 of Table 1, when the trace element content is: Nb: 0.045%, V: 0.05%, Ti: When the concentration is 0.05%, the comprehensive mechanical properties of the steel plate are the best, that is, the value of the strength-plastic product is the largest; this is because trace elements inhibit the deformation and recrystallization of austenite and prevent the growth of its grains during thermal processing; the second is through The precipitation of their carbonitride compounds exerts the precipitation strengthening effect of Nb, V, and Ti; and the composite microalloying makes full use of the interaction between Nb, V, and Ti, which effectively saves resources and greatly reduces the corrosion resistance of high-strength steel. Cost of production.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can also be made without departing from the gist of the present invention. Here It is not possible to exhaustively list all the implementation methods, and any obvious changes derived from the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims (6)

1. a kind of microalloying high alumina high-ductility steel plate, it is characterised in that：The chemical composition and mass percent of the steel plate be： C：0.8% ~ 1.0%, Mn：28% ~ 30%, Al：8.0% ~ 10%, Nb：0.02~0.10%、V：0.02~0.10%、Ti：0.02~ 0.10%、N：0.02~0.08%、P<0.003%th, S<0.003%, balance of Fe and inevitable impurity.

2. the preparation method of microalloying high alumina high-ductility steel plate described in claim 1, it is characterised in that specifically include following step Suddenly：

（1）Slab is forged into after smelting, casting；

（2）Hot rolling：By heating of plate blank, after Homogenization Treatments, carry out multistage hot deformation deformation, accumulative deflection 85% ~ 90%, Rear water-cooled is rolled, is air cooled to room temperature；

（3）Solution treatment：Steel plate after hot rolling is carried out solution treatment, a period of time is incubated using solid solubility temperature is heated rapidly to Water quenching is to room temperature afterwards；

（4）Cold rolling：To carry out cold rolling after steel plate acid-washing after solution treatment, deform through multi- pass rolling, accumulation decrement is 65%~80%；

（5）Annealing：Steel plate after will be cold rolling carries out final annealing, and water quenching afterwards to room temperature obtains microalloying height Aluminum high-ductility steel plate.

3. the preparation method of microalloying high alumina high-ductility steel plate according to claim 1, it is characterised in that：Step（1）Casting Ingot heating-up temperature is 1170 ~ 1200 DEG C, 1 ~ 2h of temperature retention time, 1100 ~ 1200 DEG C of starting forging temperature, 800 ~ 900 DEG C of final forging temperature.

4. the preparation method of microalloying high alumina high-ductility steel plate according to claim 1, it is characterised in that：Step（2）Steel Base heating-up temperature is 1150 ~ 1200 DEG C, 1 ~ 2h of temperature retention time, 1100 ~ 1150 DEG C of start rolling temperature, 850 ~ 900 DEG C of finishing temperature, volume 400 ~ 500 DEG C of Qu Wendu.

5. the preparation method of microalloying high alumina high-ductility steel plate according to claim 1, it is characterised in that：Step（3）Steel Base solid solution temperature is 950 ~ 1100 DEG C, and temperature retention time is 0.5 ~ 2h.

6. the preparation method of microalloying high alumina high-ductility steel plate according to claim 1, it is characterised in that：Step（5）Move back Fiery treatment temperature is 900 ~ 1050 DEG C, and temperature retention time is 15 ~ 30min.