Forging and rolling method for improving hot rolling edge cracks of ultra-super ferritic stainless steel

Abstract

The invention relates to the technical field of extra-super ferritic stainless steel, in particular to a forging and rolling method for improving hot rolling edge cracks of the extra-super ferritic stainless steel. In order to solve the problem that the hot rolling edge crack phenomenon is easily generated in the rolling process of the super ferrite stainless steel, the novel forging and rolling method for improving the hot rolling edge crack of the super ferrite stainless steel comprises the steps of smelting, casting, casting blank three-section heating, two-round forging and intermediate heating, rough rolling, heating after rough rolling and finish rolling. The two aspects of component control and the preparation process are improved, precipitation of aluminum oxide particles is reduced, TiN and Nb (C and N) particles are prevented from clustering around the aluminum oxide particles, precipitation of brittle phases such as sigma is inhibited, grains are refined, the plasticity and toughness of the steel plate are improved, the rolling performance is improved, and the prepared ultra-super ferrite stainless steel hot-rolled plate is free of edge cracks.

Description

Technical Field

[0001] The invention relates to the technical field of super ferrite stainless steel, in particular to a forging method for improving hot-rolled edge cracks of super ferrite stainless steel. Background Art

[0002] Super ferritic stainless steel is a high-chromium, high-molybdenum, aluminum-containing ferritic stainless steel. Its high Cr and Mo contents are the key to high corrosion resistance, and its low Ni content reduces material costs. At the same time, by adding a certain amount of Al content, the precipitation of σ and χ phases is suppressed, and the precipitation of nano-scale Laves phases is promoted to pin grain boundaries and refine grains. It has good corrosion resistance, mechanical properties, and thermal conductivity. It is usually used as a low-cost heat exchange material in corrosive environments, such as the super ferritic stainless steel described in the announcement number 115652224 B and the patent name "Super ferritic stainless steel and its preparation method". Although the super ferritic stainless steel adds a certain amount of Al elements to reduce the precipitation kinetics of the σ phase, the added Al elements are easy to change the lattice constant, increase dislocation resistance, and reduce plasticity. At the same time, during the smelting process, it is easy to combine with O to precipitate alumina particles, and the alumina particles provide nucleation points for TiN and Nb (C, N), which promotes the precipitation of TiN and Nb (C, N) particles and clusters such as Figure 1 As shown in the figure, during the rolling process, large particles of alumina, TiN, and Nb (C, N) will be crushed to produce micro cracks, holes and other micro defects. Figure 2 As shown in the figure, the phenomenon of hot rolling edge cracking is prone to occur. Figure 3 As shown, how to reduce the precipitation of alumina particles in the preparation process, avoid the clustering of TiN and Nb (C, N) particles around the alumina particles, inhibit the precipitation of brittle phases and refine the grains, and improve the plasticity and toughness of the steel plate are the key to improving the hot-rolled edge cracking of super ferritic stainless steel.

[0003] Chinese patent CN114990417A discloses a smelting method for achieving purification and grain refinement of super ferritic stainless steel. The method improves the purity of molten steel, reduces alumina inclusion particles, and reduces the tendency of hot rolling cracking by adding rare earth silicon-manganese alloy. However, the Al content in the steel is low and only serves as a deoxidizer element. This method cannot be applied to super ferritic stainless steel. Summary of the invention

[0004] In order to solve the problem that hot-rolled edge cracking is easy to occur in the rolling process of super ferrite stainless steel, the present invention provides a new forging method for improving the hot-rolled edge cracking of super ferrite stainless steel.

[0005] The present invention is achieved by adopting the following technical solutions: A forging method for improving hot-rolled edge cracks of super super ferrite stainless steel comprises the following steps: 1) Smelting: The weight percentage of each element in the smelting raw material is: 25%≤Cr≤30.0%, 1.5%≤Mo≤5.5%, 1.0%≤Ni≤4.0%, C≤0.015%, N≤0.015%, 0.5%≤Al≤5.0%, 0.10%≤Nb≤0.60%, 0.10%≤Ti≤0.30%, Mn≤0.4%, Si≤0.6%, S≤0.005%, P≤0.005%, O≤0.004%, and Cr+3.3×Mo≥35%, the rest The raw materials are prepared according to the above-mentioned element ratios to obtain molten steel. (In order to reduce the purification cost, a certain content of C and N elements are retained in the raw materials. Nb and Ti elements are added to form small and dispersed Nb (C, N) and TiN compounds to stabilize the C and N elements. In order to avoid the formation of excessive and oversized Nb (C, N) and TiN compounds, C is controlled to be ≤0.015% and N is ≤0.015% in the raw materials. In order to reduce the precipitation of alumina particles, O is controlled to be ≤0.004%). 2) Casting: The molten steel obtained in step 1) is cast into a billet under argon protection, cooled to 600-800°C at a cooling rate of 10-50°C / min, and then air-cooled to room temperature; (argon protection during the casting process prevents the molten steel from contacting and reacting with elements such as O and N in the air, inhibiting the formation of alumina particles, and cooling to 600-800°C at a relatively fast cooling rate to prevent TiN and Nb (C, N) particles from precipitating and clustering around the alumina particles) 3) Multi-stage heating of ingot: The first stage of heating: heat the ingot obtained in step 2) to 400-650°C, with a heating rate of 0.5-10°C / min and a holding time of 60-90min; (the first stage of heating is to slowly increase the temperature to ensure uniform heating of the ingot as a whole) Second stage heating: heat the ingot to 1000-1100℃, heating rate ≥25℃ / min, keep warm for 60-90min; (Second stage heating, increase the heating temperature to 1000-1100℃ and quickly increase the temperature at ≥25℃ / min, avoiding the precipitation temperature range of σ and χ phases) The third stage of heating: heat the ingot to 1180-1250℃, the heating rate is 0.5-10℃ / min, and the holding time is 30-120min; (the third stage of heating, the heating temperature is 1180-1250℃, to eliminate the segregation of alloy elements such as Cr, Mo, Nb, Al during the casting process, so that the alloy elements are fully dissolved and evenly distributed, and the casting stress is eliminated at the same time); 4) Forging The heated ingot obtained in step 3) is subjected to multiple rounds of forging.

[0006] First round of forging: the starting forging temperature is 1150-1200℃, and the final forging temperature is ≥1000℃; (If the forging temperature is too high, the grain size will be coarse; if the forging temperature is too low, the forging deformation resistance will be too large, the plasticity will be poor, and the forging difficulty will be high) Intermediate heating: Heat the first round of forgings to 1100-1200℃ and keep warm for 15-120min; (intermediate heating obtains fine grain structure through recrystallization and improves the plasticity and toughness of forgings) Second round forging: the starting forging temperature is 1050-1150℃, the final forging temperature is ≥950℃, and the forgings are obtained by air cooling after forging; (if the final forging temperature is too low, the deformation resistance of the forgings will be too large, and cracks will easily appear. The slow cooling by air cooling ensures the uniformity of the forging structure, reduces the residual stress, and prevents the subsequent hot rolling edge cracks) 5) Rough rolling The forging obtained in step 4) is heated to 1100-1200°C, the heating rate is ≥25°C / min, the temperature is kept for 0.5-3h, and multiple rough rolling is adopted, the starting rolling temperature is 1080-1180°C, the final rolling temperature is 950-1000°C, the single-pass reduction rate is ≥15%, and the total reduction rate is ≥50% to obtain a rough-rolled plate; (during the second round of forging, it is inevitable to cause the interface elements to segregate and even cause the precipitation of the intermediate phase. Therefore, during the rough rolling, the forging is first heated to dissolve the elements such as Cr, Mo, Nb, Al and other elements segregated at the interface to avoid the precipitation of brittle phases such as Cr23C6, σ phase, and χ phase. At the same time, the high-temperature heating completes the recrystallization of the deformed structure formed by forging, reduces the rolling deformation resistance, improves the plastic toughness of the steel plate, and prevents rough rolling edge cracking; at the same time, a large number of deformation microstructures such as deformation bands and shear bands are formed by rough rolling with a large reduction rate, and the deformation energy storage is increased, which provides nucleation particles and driving force for the reheating after rough rolling to complete recrystallization) 6) Heating after rough rolling The rough rolled plate obtained in step 5) is heated to 1050-1150°C; (heating after rough rolling causes the rough rolled deformed structure to recrystallize and refine the grains, further improving the plastic toughness of the steel plate) 7) Finish rolling The rough rolled sheet heated in step 6) is subjected to multiple passes of finishing rolling, with the starting rolling temperature of 1000-1100°C, the final rolling temperature of 650-850°C, and the final rolling reduction rate of 15-50%. (Since the Al element inhibits the precipitation of σ and χ phases, low-temperature final rolling can be used under the premise of preventing hot rolling edge cracking. Low-temperature final rolling forms a large deformation structure, improves deformation energy storage, and refines grains. In addition, the finishing rolling temperature range is the Laves phase precipitation range. While avoiding the precipitation of Nb (C, N) particles, the excess Nb element in the steel is transformed into a favorable nano-scale Laves phase, and then the nano-scale Laves phase is used to pin the grain boundary and refine the grains.

[0007] Furthermore, in step 1), the aluminum added to the smelting raw materials is granular aluminum with a particle size of ≤5 mm. During smelting, the raw materials except the granular aluminum are first placed in a medium frequency induction vacuum furnace crucible for smelting at a smelting temperature of 1600-1680°C, and then the temperature is reduced to 1500-1580°C before adding the granular aluminum for refining to obtain molten steel, so as to ensure that the Al element is fully dissolved and evenly distributed.

[0008] Furthermore, in step 4), the forging ratio of the first round of forging is 3 to 8 to ensure the deformation effect of the first round of forging.

[0009] The present invention controls the smelting of low-content C, N, and O impurity elements, reduces the precipitation of alumina particles, avoids the precipitation of TiN and Nb (C, N) particles around the alumina particles, and makes the TiN and Nb (C, N) particles small and dispersed; step 2) casting under argon protection to avoid the molten steel from contacting and reacting with elements such as O and N in the air, inhibiting the generation of alumina particles, and cooling to 600-800° C. at a relatively fast speed to avoid the precipitation of TiN and Nb (C, N) particles around the alumina particles and cluster distribution; step 3) multi-stage heating of the ingot to ensure that the entire ingot is evenly heated, while avoiding the precipitation of σ and χ phases. The temperature range is set to eliminate the segregation of elements such as Cr, Mo, Nb, and Al during the casting process, so that the alloy elements are fully dissolved and evenly distributed; after heating, the billet is subjected to multiple rounds of forging in step 4) to control the forging temperature, reduce the deformation resistance of the forging, prevent forging cracks, and improve the forging efficiency. After the first round of forging, secondary heating is performed to obtain a recrystallized fine structure to improve the plastic toughness, followed by a second round of forging, air cooling to room temperature to homogenize the forging structure, reduce residual stress, and prevent subsequent hot rolling edge cracks; the forging is heated in step 5) to dissolve the Cr, Mo, Nb, Al and other elements that are segregated at the interface caused by the second round of forging, avoiding Cr 23 Brittle phases such as C6, σ phase, and χ phase are precipitated to improve the plastic toughness of the steel plate and prevent edge cracking during rough rolling. At the same time, a large number of deformation microstructures such as deformation bands and shear bands are formed through rough rolling with a large reduction rate to improve deformation energy storage; then step 6) is carried out to heat the rough rolling deformation structure to recrystallize and refine the grains, further improving the plastic toughness of the steel plate, and at the same time, the subsequent finishing rolling temperature is controlled to avoid cracking during the finishing rolling process; finally, the heated rough rolled plate is subjected to step 7) multi-pass finishing rolling, and low-temperature final rolling is adopted to form a large number of deformation structures such as shear bands and deformation bands to improve deformation energy storage. At the same time, the finishing rolling temperature range is the Laves phase easy precipitation range, while avoiding the precipitation of Nb (C, N) particles, the excess Nb element is transformed into a favorable nano-scale Laves phase.

[0010] The beneficial effects of the present invention are as follows: by controlling the impurity elements of C, N, and O, the present invention adopts a preparation process of smelting, rapid cooling after casting, three-stage ingot heating, two-round forging with intermediate heating, rough rolling, heating after rough rolling, and fine rolling, thereby reducing the precipitation of alumina particles, avoiding the clustering of TiN and Nb (C, N) particles around the alumina particles, and inhibiting the precipitation of brittle phases such as σ phase, refining the grains, improving the plastic toughness of the steel plate, and improving the rolling performance. The prepared ultra-super ferrite stainless steel hot-rolled plate has no edge cracking phenomenon, and no brittle phases such as σ and χ phases and alumina particles are observed in the steel, and only a small amount of TiN and Nb (C, N) particles are dispersed and distributed, as well as a large amount of nano-scale Laves phases. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0012] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0013] Figure 1 It is the clustering phenomenon of TiN and Nb (C, N) particles in the hot-rolled plate of the existing process; Figure 2 The micro cracks are caused by TiN and Nb (C, N) particle clusters in the hot-rolled plate of the existing process; Figure 3 A physical picture of edge cracks in hot-rolled plates prepared by existing technology; Figure 4 The microstructure of the forged part forged by the present invention; Figure 5 The hot-rolled plate microstructure of the present invention, wherein the white phase is a nanoscale Laves phase; Figure 6 This is the phenomenon of dispersed distribution of TiN and Nb (C, N) particles in the hot-rolled plate of the present invention, wherein the black particles are TiN and the white phase around TiN is Nb (C, N); Figure 7 This is a physical picture of the hot-rolled plate prepared by the process of the present invention. DETAILED DESCRIPTION

[0014] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0015] In the description, it should be noted that the terms "first" and "second" are only used for descriptive purposes and should not be understood as indicating or implying relative importance. It should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internal communication between two elements. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0016] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all of the embodiments.

[0017] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. Embodiment 1

[0018] A forging method for improving hot-rolled edge cracks of super super ferrite stainless steel comprises the following steps: 1) Melting: The weight percentage of each element in the smelting raw material is: 30.0% Cr, 1.7% Mo, 1.0% Ni, 0.015% C, 0.015% N, 5.0% Al, 0.10% Nb, 0.30% Ti, 0.4% Mn, 0.6% Si, 0.005% S, 0.005% P, 0.004% O, and the rest is Fe and inevitable impurities. The raw materials are prepared according to the above element ratios and then smelted to obtain molten steel, wherein the aluminum added to the smelting raw materials is granular aluminum with a particle size of ≤5mm. During smelting, the raw materials except the granular aluminum are first placed in a medium frequency induction vacuum furnace crucible for smelting at a smelting temperature of 1680°C, and then the granular aluminum is added after the temperature is reduced to 1580°C for refining to obtain molten steel, so as to ensure that the Al element is fully dissolved and evenly distributed; 2) Casting: The molten steel obtained in step 1) is cast into a billet under argon protection, cooled to 800° C. at a cooling rate of 10° C. / min, and then air-cooled to room temperature; 3) Multi-stage heating of ingot: First stage heating: heating the ingot obtained in step 2) to 650°C, with a heating rate of 10°C / min and a holding time of 90min; Second stage heating: heat the ingot to 1100°C, heating rate 40°C / min, keep warm for 90min; The third stage of heating: heat the ingot to 1250℃, the heating rate is 10℃ / min, and the holding time is 120min; 4) Forging The heated ingot obtained in step 3) is subjected to multiple rounds of forging; First round forging: start forging temperature is 1200℃, final forging temperature is 1050℃, first round forging ratio is 3; Intermediate heating: heat the first round forging to 1200℃ and keep warm for 120min; Second round forging: the starting forging temperature is 1150℃, the final forging temperature is 1000℃, the thickness is forged to 50mm, and the forging is air-cooled after forging; 5) Rough rolling The forging obtained in step 4) is heated to 1200°C, the heating rate is 40°C / min, the temperature is kept for 3 hours, and multiple passes of rough rolling are adopted, the starting rolling temperature is 1180°C, the final rolling temperature is 1000°C, the single pass reduction rate is 15%, and the total reduction rate is 50% to obtain a rough rolled plate; 6) Heating after rough rolling The rough rolled sheet obtained in step 5) is heated to 1150° C.; 7) Finish rolling The rough rolled sheet heated in step 6) is subjected to multiple passes of finish rolling, with a starting rolling temperature of 1100° C., a final rolling temperature of 850° C., and a final rolling reduction rate of 50%. Embodiment 2

[0019] A forging method for improving hot-rolled edge cracks of super super ferrite stainless steel comprises the following steps: 1) Melting: The weight percentage of each element in the smelting raw material is: 25.0% Cr, 5.5% Mo, 4.0% Ni, 0.015% C, 0.015% N, 0.5% Al, 0.60% Nb, 0.10% Ti, 0.3% Mn, 0.5% Si, 0.005% S, 0.005% P, 0.003% O, and the rest is Fe and inevitable impurities. The raw materials are prepared according to the above element ratios and then melted to obtain molten steel, wherein the aluminum added to the smelting raw materials is granular aluminum with a particle size of ≤5mm. During the melting, the raw materials except the granular aluminum are first placed in a medium frequency induction vacuum furnace crucible for melting at a melting temperature of 1600°C, and then the granular aluminum is added after the temperature is reduced to 1500°C for refining to obtain molten steel, so as to ensure that the Al element is fully dissolved and evenly distributed; 2) Casting: The molten steel obtained in step 1) is cast into a billet under argon protection, cooled to 600° C. at a cooling rate of 50° C. / min, and then air-cooled to room temperature; 3) Multi-stage heating of ingot: First stage heating: heating the ingot obtained in step 2) to 400°C, with a heating rate of 0.5°C / min and a holding time of 60min; Second stage heating: heat the ingot to 1000°C, heating rate 25°C / min, keep warm for 60min; The third stage of heating: heat the ingot to 1180℃, the heating rate is 0.5℃ / min, and the holding time is 30min; 4) Forging The heated ingot obtained in step 3) is subjected to multiple rounds of forging; First round forging: start forging temperature is 1150℃, final forging temperature is 1000℃, first round forging ratio is 8; Intermediate heating: heat the first round forging to 1100℃ and keep warm for 15min; Second round forging: the starting forging temperature is 1050℃, the final forging temperature is 950℃, the thickness is forged to 20mm, and the forging is air-cooled after forging; 5) Rough rolling The forging obtained in step 4) is heated to 1100°C, the heating rate is 25°C / min, the temperature is kept for 0.5h, and multiple passes of rough rolling are adopted, the starting rolling temperature is 1080°C, the final rolling temperature is 950°C, the single pass reduction rate is 15%, and the total reduction rate is 70% to obtain a rough rolled plate; 6) Heating after rough rolling The rough rolled sheet obtained in step 5) is heated to 1050° C.; 7) Finish rolling The rough rolled sheet heated in step 6) is subjected to multiple passes of finish rolling, with a starting rolling temperature of 1000°C, a final rolling temperature of 650°C, and a final rolling reduction rate of 15%. Embodiment 3

[0020] A forging method for improving hot-rolled edge cracks of super super ferrite stainless steel comprises the following steps: 1) Melting: The weight percentage of each element in the smelting raw material is: 27.5% Cr, 3.5% Mo, 2.5% Ni, 0.01% C, 0.01% N, 1.5% Al, 0.40% Nb, 0.20% Ti, 0.3% Mn, 0.5% Si, 0.005% S, 0.005% P, 0.004% O, and the rest is Fe and inevitable impurities. The raw materials are prepared according to the above element ratios and then smelted to obtain molten steel, wherein the aluminum added to the smelting raw materials is granular aluminum with a particle size of ≤5mm. During smelting, the raw materials except the granular aluminum are first placed in a medium frequency induction vacuum furnace crucible for smelting at a smelting temperature of 1650°C, and then the granular aluminum is added after the temperature is reduced to 1550°C for refining to obtain molten steel, so as to ensure that the Al element is fully dissolved and evenly distributed; 2) Casting: The molten steel obtained in step 1) is cast into a billet under argon protection, cooled to 700° C. at a cooling rate of 30° C. / min, and then air-cooled to room temperature; 3) Multi-stage heating of ingot: First stage heating: heating the ingot obtained in step 2) to 500°C, with a heating rate of 2.5°C / min and a holding time of 60min; Second stage heating: heat the ingot to 1050°C, heating rate 30°C / min, keep warm for 90min; The third stage of heating: heating the ingot to 1200℃, with a heating rate of 5℃ / min and a holding time of 60min; 4) Forging The heated ingot obtained in step 3) is subjected to multiple rounds of forging; First round forging: start forging temperature is 1170℃, final forging temperature is 1020℃, first round forging ratio is 4.5; intermediate heating: heat the first round forging to 1150℃ and keep warm for 30min; Second round forging: the starting forging temperature is 1100℃, the final forging temperature is 970℃, the thickness is forged to 30mm, and the forging is air-cooled after forging; 5) Rough rolling The forging obtained in step 4) is heated to 1150°C, the heating rate is 30°C / min, the temperature is kept for 2h, and multiple passes of rough rolling are adopted, the starting rolling temperature is 1130°C, the final rolling temperature is 950°C, the single pass reduction rate is 20%, and the total reduction rate is 75% to obtain a rough rolled plate; 6) Heating after rough rolling The rough rolled sheet obtained in step 5) is heated to 1100° C.; 7) Finish rolling The rough rolled sheet heated in step 6) is subjected to multiple passes of finish rolling, with a starting rolling temperature of 1050°C, a final rolling temperature of 700°C, and a final rolling reduction rate of 20%.

[0021] In the above embodiments, no brittle phases such as σ and χ phases and alumina particles were observed in the forgings and hot-rolled plates. Figure 4 , 5 , 6 (the phenomena of the three embodiments are basically the same, so a group of figures are given in this application to illustrate the experimental phenomena), only a small amount of TiN and Nb (C, N) particles are dispersed and a large amount of nano-scale Laves phase (super-ferrite stainless steel uses Al element to promote the precipitation of nano-scale Laves phase to pin grain boundaries and refine grains), and no hot rolling edge cracking occurs during the hot rolling process, such as Figure 7 shown.

[0022] The above is only a specific implementation of the present invention, which enables those skilled in the art to understand or implement the present invention. Although detailed descriptions are given with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments, and they should all be covered by the protection scope of the claims.

Claims

1. A forging method for improving hot-rolled edge cracks of super ferrite stainless steel, characterized in that: The steps include: 1) Melting: The weight percentage of each element in the smelting raw material is: 25%≤Cr≤30.0%, 1.5%≤Mo≤5.5%, 1.0%≤Ni≤4.0%, C≤0.015%, N≤0.015%, 0.5%≤Al≤5.0%, 0.10%≤Nb≤0.60%, 0.10%≤Ti≤0.30%, Mn≤0.4%, Si≤0.6%, S≤0.005%, P≤0.005%, O≤0.004%, and Cr+3.3×Mo≥35%, the rest is Fe and unavoidable impurities. After the raw materials are prepared according to the above element ratios, they are melted to obtain molten steel; 2) Casting: The molten steel obtained in step 1) is cast into a casting billet under argon protection, cooled to 600-800° C. at a cooling rate of 10-50° C. / min, and then air-cooled to room temperature; 3) Multi-stage heating of ingot: The first stage of heating: heating the ingot obtained in step 2) to 400-650°C, with a heating rate of 0.5-10°C / min and a holding time of 60-90min; Second stage heating: heat the ingot to 1000-1100℃, heating rate ≥25℃ / min, keep warm for 60-90min; The third stage of heating: heat the ingot to 1180-1250℃, the heating rate is 0.5-10℃ / min, and the holding time is 30-120min; 4) Forging: The heated ingot obtained in step 3) is subjected to multiple rounds of forging; First round forging: start forging temperature is 1150-1200℃, final forging temperature is ≥1000℃; intermediate heating: heat the first round forging to 1100-1200℃, keep warm for 15-120min; Second round forging: the starting forging temperature is 1050-1150℃, the final forging temperature is ≥950℃, and the forgings are obtained by air cooling after forging; 5) Rough rolling The forging obtained in step 4) is heated to 1100-1200°C, with a heating rate of ≥25°C / min, and kept at this temperature for 0.5-3h, and rough rolled by multiple passes, with a starting rolling temperature of 1080-1180°C, a final rolling temperature of 950-1000°C, a single pass reduction rate of ≥15%, and a total reduction rate of ≥50%, to obtain a rough rolled plate; 6) Heating after rough rolling The rough rolled sheet obtained in step 5) is heated to 1050-1150° C.; 7) Finish rolling The rough rolled sheet heated in step 6) is subjected to multiple passes of finish rolling, with a starting rolling temperature of 1000-1100° C., a final rolling temperature of 650-850° C., and a final rolling reduction rate of 15-50%.

2. A forging method for improving hot-rolled edge cracks of super ferrite stainless steel according to claim 1, characterized in that: In step 1), the aluminum added to the smelting raw materials is granular aluminum with a particle size of ≤5 mm. During smelting, the raw materials except the granular aluminum are first placed in a medium frequency induction vacuum furnace crucible for smelting at a smelting temperature of 1600-1680° C., and then the temperature is lowered to 1500-1580° C. before adding the granular aluminum for refining to obtain molten steel.

3. A forging method for improving hot-rolled edge cracks of super ferrite stainless steel according to claim 2, characterized in that: The forging ratio of the first round of forging in step 4) is 3 to 8.

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