Rolling and temperature control process for 04Cr13Ni5Mo stainless steel plate

Abstract

The invention relates to the technical field of martensitic steel, in particular to a 04Cr13Ni5Mo stainless steel plate rolling and temperature control process, which comprises the following steps: heating a pretreated blank to 1190-1210 DEG C at a heating rate of more than 0 DEG C and less than or equal to 5 DEG C / min, and soaking for more than or equal to 2 hours; the rolling reduction rate of the blank is controlled to be 12%-15%, and compared with the reduction rate of the pass before final rolling, the reduction rate is reduced by 20%-25%; stacking slow cooling is larger than or equal to 550 DEG C, and the plate yield is increased by 30% or Through heat treatment processes of normalizing at 1040 DEG C + / -10 DEG C, preserving heat of a plate with the thickness of 85 mm for 4 hours, preserving heat of a plate with the thickness of 115 mm for 5 hours, tempering at 620 DEG C + / -10 DEG C, preserving heat of the plate with the thickness of 85 mm for 6 hours and preserving heat of the plate with the thickness of 115 mm for 8 hours, the yield ratio is stabilized at 0.8-0.85, and the uniformity of mechanical properties is improved by 25%. The stable yield ratio reduces the deformation amplitude of plates and workpieces by more than 40% during later processing, additional repair is not needed, and the production cost is reduced.

Description

Technical Field

[0001] This invention relates to the technical field of stainless steel rolling methods, specifically a rolling and temperature control process for 04Cr13Ni5Mo stainless steel plates. Background Technology

[0002] 04Cr13Ni5Mo stainless steel, as a martensitic steel, is highly favored in fields such as hydropower engineering due to its excellent mechanical properties and corrosion resistance, and is often manufactured into thick plates of 85mm and 115mm. Currently, mainstream stainless steel rolling processes (whose core processes include billet pretreatment, heating, rolling, straightening, cooling, heat treatment, and testing) are mainly designed for common austenitic or ferritic steel grades. However, existing general processes have not been specifically optimized for the martensitic characteristics of 04Cr13Ni5Mo steel, which to some extent restricts the further improvement and stabilization of the performance of its thick plate products.

[0003] The 04Cr13Ni5Mo stainless steel produced using a rolling process designed for ordinary austenitic or ferritic steel grades has significant process defects: First, it has poor thermal conductivity, resulting in a large temperature difference between the surface and the center during heating, which easily leads to thermal stress cracking; second, it has high temperature sensitivity, with excessively high heating temperatures causing phase transformation and decreased plasticity, making it prone to cracking during rolling; third, it requires high uniformity of deformation, with high resistance to high-temperature deformation, and insufficient or uneven deformation can lead to the formation of coarse martensite after cooling, affecting performance; fourth, it is sensitive to cooling, and even single-piece air cooling may produce cooling cracks; fifth, existing technologies do not focus on controlling its yield strength ratio, and the plate and workpiece are prone to large deformations during later processing (such as cutting and bending), affecting the accuracy of the finished product.

[0004] Therefore, it is essential to develop a temperature control process for rolling stainless steel plates to achieve precise temperature control, uniform deformation, and slow cooling protection in order to solve the problems of thermal stress cracking, decreased plasticity, uneven deformation, and cooling cracking in the production of 04Cr13Ni5Mo. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a rolling and temperature control process for 04Cr13Ni5Mo stainless steel plates, which solves the problems of thermal stress cracking, decreased plasticity, uneven deformation, and cooling cracking during the rolling process of 04Cr13Ni5Mo, and achieves precise temperature control, uniform deformation, and slow cooling protection.

[0006] To solve the above-mentioned technical problems, the present invention provides a rolling and temperature control process for 04Cr13Ni5Mo stainless steel plates, comprising the following steps: The pretreated stainless steel billet is heated to 1190℃~1210℃ at a heating rate of 0℃ / min < heating rate ≤ 5℃ / min, and homogenized at this temperature for ≥ 2 hours. During the entire heating and homogenization process, an inert gas is introduced to maintain a uniform protective atmosphere. The heated stainless steel billet is then subjected to rough rolling and multi-pass finishing rolling. The finishing rolling temperature is ≥ 950℃, and the final rolling temperature is 850℃~920℃. The single-pass reduction rate of each finishing rolling pass is 12%~15%, and the reduction rate of the previous pass before entering the final rolling is reduced by 20%~25% to obtain the rolled plate. To avoid uneven deformation of the sheet metal, the rolled sheet must be straightened and then placed in an environment with a temperature ≥550℃ for slow cooling for 8h~10h, and then allowed to cool naturally to room temperature. The plates, after slow cooling, are subjected to normalizing and tempering heat treatment. The normalizing temperature is 1030℃~1050℃, and the plates are heated for 8 hours. The plates with a thickness of 85mm are held at this temperature for 4 hours, and the plates with a thickness of 115mm are held at this temperature for 5 hours. After air cooling to room temperature, the plates are then tempered at 610℃~630℃ for 6 hours~8 hours. The plates with a thickness of 85mm are held at this temperature for 6 hours, and the plates with a thickness of 115mm are held at this temperature for 8 hours. After a second air cooling, 04Cr13Ni5Mo stainless steel plates are obtained.

[0007] Preferably, to provide sufficient rolling deformation and ensure uniform internal and external temperatures of the billet during heating to avoid thermal stress cracking, the thickness of the stainless steel billet is ≥320mm.

[0008] Preferably, to avoid increased deformation due to uneven stress during later cutting and bending, the flatness of the straightened rolled plate should be 0 < ≤ 0.5 mm / m.

[0009] Preferably, to avoid cracks and defects in the finished product, pickling is used to remove the oxide scale on the surface of the stainless steel billet, and qualified stainless steel billets are screened at the same time.

[0010] Preferably, to avoid excessive temperature drop in the heated stainless steel billet and reduce the additional cooling of the rolled piece by the descaling water, the amount of cooling water used during rough rolling and the number of descaling passes after rough rolling are controlled to ensure that the heated stainless steel billet meets the finishing rolling temperature of ≥950℃. During finishing rolling, the amount of cooling water is controlled to ensure that the final rolling temperature is 850℃~920℃, thereby controlling the finishing and final rolling temperatures. Adjusting the amount of cooling water used in the roughing and finishing rolling rolls is tailored to the characteristics of 04Cr13Ni5Mo steel, and is combined with strict control of the number of descaling passes to reduce additional cooling water, thus preventing abnormal temperature drops in the heated stainless steel billet.

[0011] This invention provides a 4Cr13Ni5Mo stainless steel plate, which is manufactured using a temperature-controlled rolling process for 04Cr13Ni5Mo stainless steel plates.

[0012] Preferably, the 04Cr13Ni5Mo stainless steel plate has a yield strength of 639 MPa, a tensile strength of 892.2 MPa, an elongation of 23%, and a hardness of HB277.

[0013] Preferably, the yield strength ratio of the 04Cr13Ni5Mo stainless steel plate is 0.8~0.85.

[0014] Preferably, the processing deformation range of the 04Cr13Ni5Mo stainless steel plate is ≤1.2mm / m.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The 04Cr13Ni5Mo stainless steel described in the prior art is a martensitic steel, which has defects such as poor thermal conductivity, temperature sensitivity, easy generation of thermal stress due to uneven heating, phase transformation of the microstructure due to excessively high temperature, decreased plasticity, uneven deformation due to insufficient or uneven reduction rate, and coarse grains after cooling. The temperature control process for rolling 04Cr13Ni5Mo stainless steel plates provided in this invention controls the heating rate of the pretreated billet to 1℃ / min ≤ heating rate ≤ 5℃ / min and the homogenization heating time within 1190℃~1210℃ for ≥2h, while introducing inert gas to achieve precise temperature control. This eliminates cracks caused by thermal stress due to uneven heating, improves thermal conductivity, and reduces temperature sensitivity. Controlling the finishing and final rolling temperatures avoids phase transformation and decreased plasticity caused by excessive temperature, while providing a suitable temperature environment for uniform rolling and grain refinement, ensuring stable mechanical properties of the plate. By controlling the billet rolling reduction rate to 12%~15% and reducing the reduction rate of the previous rolling pass by 20%~25%, uniform deformation is achieved, ensuring grain refinement and plate shape. By controlling the slow cooling at ≥550℃ for 8h~10h, cooling cracking is avoided, thus preventing decreased plasticity and uneven deformation, solving the defect of coarse grains after cooling, and increasing the plate yield by more than 30%. By controlling the heat treatment process of normalizing at 1040℃±10℃ and holding 85mm thick plates for 4 hours, and 115mm thick plates for 5 hours, followed by tempering at 620℃±10℃ and holding 85mm thick plates for 6 hours, and 115mm thick plates for 8 hours, the yield strength ratio of 04Cr13Ni5Mo was stabilized at 0.8~0.85, and the uniformity of mechanical properties was improved by 25%. The stable yield strength ratio reduces the deformation of the plates and workpieces by more than 40% during subsequent processing, eliminating the need for additional repairs, reducing production costs, and meeting the precision requirements of hydropower projects. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the heating and rolling process in Examples 1 to 5 of the present invention.

[0017] Figure 2 This is a schematic diagram of the overall leveling process in Embodiments 1 to 5 of the present invention. Detailed Implementation

[0018] To make the above-mentioned objectives, features, and advantages of the embodiments of the present invention more apparent and understandable, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] It should be noted that when numerical ranges are involved in this invention, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as those in Embodiments 1 to 5, preferred embodiments are described in this invention to avoid redundancy. However, this invention is not limited to these, but can be specifically implemented in other ways within the scope of the technical solutions defined in the appended claims.

[0020] In the following embodiments, unless otherwise specified, the methods described are conventional methods, and the reagents described are commercially available unless otherwise specified.

[0021] The technical solution of the present invention will be further illustrated below with specific examples.

[0022] Example 1 like Figure 1 and Figure 2 As shown, a rolling and temperature control process for 04Cr13Ni5Mo stainless steel plate includes the following steps: 320mm thick blanks without impurities or defects are selected and surface-cleaned by pickling to remove the oxide scale from the surface of the stainless steel blanks.

[0023] The pretreated stainless steel billet is heated to 1200℃ at a preheating rate of 4℃ / min using heating furnace 1, and then homogenized at this temperature for 2.5h. During the entire heating and homogenization process, inert gas needs to be introduced to maintain a uniform protective atmosphere.

[0024] The heated stainless steel billet is roughed and finished using roughing mill 2 and finishing mill 3. The finishing temperature is 960℃ and the final rolling temperature is 880℃. The single-pass reduction rate of each finishing rolling pass is 13%, and the reduction rate of the previous pass before entering the final rolling is reduced by 20%. The cooling water for rolling is reduced, and descaling is only performed once after roughing to obtain an 85mm rolled plate.

[0025] The 85mm rolled plate was straightened at point 4 on the feed rollers to ensure a flatness of 0.5mm / m. The straightened 85mm plate was then placed in a stacking rack, and the rack temperature was maintained at 560℃ for slow cooling treatment for 8 hours.

[0026] After slow cooling, the sheet material was heated at 1050℃ for 8 hours in a heating and finishing mechanism, held at that temperature for 4 hours, air-cooled to room temperature, and after an interval of 9 hours, it was tempered at 630℃ for 8 hours, held at that temperature for 6 hours, and then air-cooled a second time to obtain an 85mm thick 04Cr13Ni5Mo stainless steel sheet.

[0027] Example 2 like Figure 1 and Figure 2 As shown, a rolling and temperature control process for 04Cr13Ni5Mo stainless steel plate includes the following steps: 320mm thick blanks without impurities or defects are selected and surface-cleaned by pickling to remove the oxide scale from the surface of the stainless steel blanks.

[0028] The pretreated stainless steel billet is heated to 1195°C at a preheating rate of 3°C / min using a heating furnace 1, and then homogenized at this temperature for 3 hours. During the entire heating and homogenization process, an inert gas is introduced to maintain a uniform protective atmosphere.

[0029] The heated stainless steel billet is roughed and finished using roughing mill 2 and finishing mill 3. The finishing temperature is 955℃ and the final rolling temperature is 860℃. The single-pass reduction rate of each finishing rolling pass is 14%, and the reduction rate of the previous pass before entering the final rolling is reduced by 25%. The cooling water for rolling is reduced, and descaling is only performed once after roughing to obtain a 115mm rolled plate.

[0030] The 115mm rolled plate was straightened at point 4 on the feed rollers to ensure a flatness of 0.4mm / m. The straightened 115mm plate was then placed in a stacking rack, and the rack temperature was maintained at 570℃ for slow cooling treatment for 10 hours.

[0031] After slow cooling, the sheet material was heated at 1030℃ for 8 hours in a heating and finishing unit, held at that temperature for 5 hours, air-cooled to room temperature, and after an interval of 8.5 hours, it was tempered at 610℃ for 6 hours, held at that temperature for 8 hours, and then air-cooled a second time to obtain a 115mm thick 04Cr13Ni5Mo stainless steel sheet.

[0032] Example 3 like Figure 1 and Figure 2 As shown, a rolling and temperature control process for 04Cr13Ni5Mo stainless steel plate includes the following steps: 320mm thick blanks without impurities or defects are selected and surface-cleaned by pickling to remove the oxide scale from the surface of the stainless steel blanks.

[0033] The pretreated stainless steel billet is heated to 1210℃ at a preheating rate of 2℃ / min using heating furnace 1, and then homogenized at this temperature for 3 hours. During the entire heating and homogenization process, inert gas needs to be introduced to maintain a uniform protective atmosphere.

[0034] The heated stainless steel billet is roughed and finished using roughing mill 2 and finishing mill 3. The finishing temperature is 980℃ and the final rolling temperature is 920℃. The single-pass reduction rate of each finishing rolling pass is 15%, and the reduction rate of the previous pass before entering the final rolling is reduced by 20%. The cooling water for rolling is reduced, and descaling is only performed once after roughing to obtain an 85mm rolled plate.

[0035] The 85mm rolled plate was straightened at point 4 on the feed rollers to ensure a flatness of 0.3mm / m. The straightened 85mm plate was then placed in a stacking rack, and the rack temperature was maintained at 580℃ for slow cooling treatment for 8 hours.

[0036] After slow cooling, the sheet material was heated at 1040℃ for 8 hours in a heating and finishing unit, held at that temperature for 4 hours, air-cooled to room temperature, and after an interval of 10 hours, it was tempered at 620℃ for 7 hours, held at that temperature for 6 hours, and then air-cooled a second time to obtain an 85mm thick 04Cr13Ni5Mo stainless steel sheet.

[0037] Example 4 like Figure 1 and Figure 2 As shown, a rolling and temperature control process for 04Cr13Ni5Mo stainless steel plate includes the following steps: 330mm thick blanks without impurities or defects are selected and surface-cleaned by pickling to remove the oxide scale from the surface of the stainless steel blanks.

[0038] The pretreated stainless steel billet is heated to 1190℃ at a preheating rate of 1℃ / min using heating furnace 1, and then homogenized at this temperature for 4 hours. During the entire heating and homogenization process, inert gas is introduced to maintain a uniform protective atmosphere.

[0039] The heated stainless steel billet is roughed and finished using roughing mill 2 and finishing mill 3. The finishing temperature is 1000℃ and the final rolling temperature is 860℃. The single-pass reduction rate of each finishing rolling pass is 13%, and the reduction rate of the previous pass before entering the final rolling is reduced by 22%. The cooling water is reduced, and descaling is only performed once after roughing to obtain a 115mm rolled plate.

[0040] The 115mm rolled plate was straightened at point 4 on the feed rollers to ensure a flatness of 0.1mm / m. The straightened 115mm plate was then placed in a stacking rack, and the rack temperature was maintained at 590℃ for slow cooling treatment for 8 hours.

[0041] After slow cooling, the sheet material was heated at 1030℃ for 8 hours in a heating and finishing mechanism, held at that temperature for 5 hours, air-cooled to room temperature, and after an interval of 9 hours, it was tempered at 610℃ for 8 hours, held at that temperature for 8 hours, and then air-cooled a second time to obtain a 115mm thick 04Cr13Ni5Mo stainless steel sheet.

[0042] Example 5 like Figure 1 and Figure 2 As shown, a rolling and temperature control process for 04Cr13Ni5Mo stainless steel plate includes the following steps: 320mm thick blanks without impurities or defects are selected and surface-cleaned by pickling to remove the oxide scale from the surface of the stainless steel blanks.

[0043] The pretreated stainless steel billet is heated to 1205℃ at a preheating rate of 5℃ / min using heating furnace 1, and then homogenized at this temperature for 2 hours. During the entire heating and homogenization process, inert gas needs to be introduced to maintain a uniform protective atmosphere.

[0044] The heated stainless steel billet is roughed and finished using roughing mill 2 and finishing mill 3. The finishing temperature is 950℃ and the final rolling temperature is 900℃. The single-pass reduction rate of each finishing rolling pass is 14%, and the reduction rate of the previous pass before entering the final rolling is reduced by 25%. The cooling water for rolling is reduced, and descaling is only performed once after roughing to obtain an 85mm rolled plate.

[0045] The 85mm rolled plate was straightened at point 4 on the feed rollers to ensure a flatness of 0.5mm / m. The straightened 85mm plate was then placed in a stacking rack, and the rack temperature was maintained at 570℃ for slow cooling treatment for 8 hours.

[0046] After slow cooling, the sheet material was heated at 1050℃ for 8 hours in a heating and finishing mechanism, held at that temperature for 4 hours, air-cooled to room temperature, and then tempered at 610℃ for 6 hours after an 8-hour interval. After a second air cooling, an 85mm thick 04Cr13Ni5Mo stainless steel sheet was obtained.

[0047] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the heating rate is 6℃ / min and the soaking time is 1.5h; the single-pass reduction rate of finishing rolling is 10%, and the reduction amount of the last pass before final rolling remains unchanged; natural air cooling (without stacking and slow cooling); heat treatment normalizing at 1000℃ for 3h and tempering at 610℃ for 5h.

[0048] A rolling and temperature control process for 04Cr13Ni5Mo stainless steel plate includes the following steps: 320mm thick blanks without impurities or defects are selected and surface-cleaned by pickling to remove the oxide scale from the surface of the stainless steel blanks.

[0049] The pretreated stainless steel billet is heated to 1200℃ at a preheating rate of 6℃ / min using heating furnace 1, and then homogenized at this temperature for 1.5h. During the entire heating and homogenization process, inert gas needs to be introduced to maintain a uniform protective atmosphere.

[0050] The heated stainless steel billet is roughed and then finished using a roughing mill 2 and a finishing mill 3. The finishing temperature is 960℃ and the final rolling temperature is 880℃. The single-pass reduction rate of each finishing mill is 10%, resulting in an 85mm rolled plate.

[0051] The 85mm rolled plate is straightened at point 4 on the feed rollers to ensure a flatness of 0.5mm / m. It is then air-cooled.

[0052] After slow cooling, the 85mm thick plate was heated at 1000℃ for 3 hours in a heating finishing unit, held for 4 hours, air-cooled to room temperature, and after an interval of 9 hours, it was tempered at 610℃ for 6 hours, held for 5 hours, and then air-cooled a second time to obtain an 85mm thick 04Cr13Ni5Mo stainless steel plate.

[0053] Comparative Example 2 The difference between Comparative Example 2 and Example 2 is that the heating rate and homogenization time of the pretreated billet are changed.

[0054] A rolling and temperature control process for 04Cr13Ni5Mo stainless steel plate includes the following steps: 320mm thick blanks without impurities or defects are selected and surface-cleaned by pickling to remove the oxide scale from the surface of the stainless steel blanks.

[0055] The pretreated stainless steel billet is heated to 1200℃ at a preheating rate of 6℃ / min using heating furnace 1, and then homogenized at this temperature for 1.5h. During the entire heating and homogenization process, inert gas needs to be introduced to maintain a uniform protective atmosphere.

[0056] The heated stainless steel billet is roughed and finished using roughing mill 2 and finishing mill 3. The finishing temperature is 960℃ and the final rolling temperature is 880℃. The single-pass reduction rate of each finishing rolling pass is 13%, and the reduction rate of the previous pass before entering the final rolling is reduced by 20%. The cooling water for rolling is reduced, and descaling is only performed once after roughing to obtain a 115mm rolled plate.

[0057] The 115mm rolled plate was straightened at point 4 on the feed rollers to ensure a flatness of 0.5mm / m. The straightened 115mm plate was then placed in a stacking rack, and the rack temperature was maintained at 560℃ for slow cooling treatment for 8 hours.

[0058] After slow cooling, the 115mm thick plate was heated at 1030℃ for 8 hours in a heating and finishing mechanism, held at that temperature for 5 hours, air-cooled to room temperature, and after an 8.5-hour interval, it was tempered at 610℃ for 6 hours, held at that temperature for 8 hours, and then air-cooled a second time to obtain a 115mm thick 04Cr13Ni5Mo stainless steel plate.

[0059] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the single-pass reduction rate of finishing rolling is 10%, while the reduction amount of the last pass before final rolling remains unchanged.

[0060] A rolling and temperature control process for 04Cr13Ni5Mo stainless steel plate includes the following steps: 320mm thick blanks without impurities or defects are selected and surface-cleaned by pickling to remove the oxide scale from the surface of the stainless steel blanks.

[0061] The pretreated stainless steel billet is heated to 1200℃ at a preheating rate of 4℃ / min using heating furnace 1, and then homogenized at this temperature for 2.5h. During the entire heating and homogenization process, inert gas needs to be introduced to maintain a uniform protective atmosphere.

[0062] The heated stainless steel billet is roughed and finished using roughing mill 2 and finishing mill 3. The finishing temperature is 960℃ and the final rolling temperature is 880℃. The single-pass reduction rate of each finishing rolling is 10%. The cooling water is reduced and descaling is only performed once after roughing to obtain an 85mm rolled plate.

[0063] The 85mm rolled plate was straightened at point 4 on the feed rollers to ensure a flatness of 0.5mm / m. The straightened 85mm plate was then placed in a stacking rack, and the rack temperature was maintained at 560℃ for slow cooling treatment for 8 hours.

[0064] After slow cooling, the 85mm thick plate was heated at 1050℃ for 8 hours in a heating and finishing mechanism, held for 4 hours, air-cooled to room temperature, and after an interval of 9 hours, tempered at 630℃ for 8 hours, held for 6 hours, and then air-cooled a second time to obtain an 85mm thick 04Cr13Ni5Mo stainless steel plate.

[0065] Comparative Example 4 The difference between Comparative Example 4 and Example 2 is that the slow cooling of the stack was replaced by natural air cooling.

[0066] A rolling and temperature control process for 04Cr13Ni5Mo stainless steel plate includes the following steps: 320mm thick blanks without impurities or defects are selected and surface-cleaned by pickling to remove the oxide scale from the surface of the stainless steel blanks.

[0067] The pretreated stainless steel billet is heated to 1200℃ at a preheating rate of 4℃ / min using heating furnace 1, and then homogenized at this temperature for 2.5h. During the entire heating and homogenization process, inert gas needs to be introduced to maintain a uniform protective atmosphere.

[0068] The heated stainless steel billet is roughed and finished using roughing mill 2 and finishing mill 3. The finishing temperature is 960℃ and the final rolling temperature is 880℃. The single-pass reduction rate of each finishing rolling pass is 13%, and the reduction rate of the previous pass before entering the final rolling is reduced by 20%. The cooling water for rolling is reduced, and descaling is only performed once after roughing to obtain a 115mm rolled plate.

[0069] The 115mm rolled plate is straightened at point 4 on the feed rollers to ensure a flatness of 0.5mm / m. It is then air-cooled.

[0070] After slow cooling, the 115mm thick plate was heated at 1030℃ for 8 hours in a heating and finishing mechanism, held at that temperature for 5 hours, air-cooled to room temperature, and after an 8.5-hour interval, it was tempered at 610℃ for 6 hours, held at that temperature for 8 hours, and then air-cooled a second time to obtain a 115mm thick 04Cr13Ni5Mo stainless steel plate.

[0071] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that the normalizing temperature and holding time, as well as the tempering temperature and holding time, were changed.

[0072] A rolling and temperature control process for 04Cr13Ni5Mo stainless steel plate includes the following steps: 320mm thick blanks without impurities or defects are selected and surface-cleaned by pickling to remove the oxide scale from the surface of the stainless steel blanks.

[0073] The pretreated stainless steel billet is heated to 1200℃ at a preheating rate of 4℃ / min using heating furnace 1, and then homogenized at this temperature for 2.5h. During the entire heating and homogenization process, inert gas needs to be introduced to maintain a uniform protective atmosphere.

[0074] The heated stainless steel billet is roughed and finished using roughing mill 2 and finishing mill 3. The finishing temperature is 960℃ and the final rolling temperature is 880℃. The single-pass reduction rate of each finishing rolling pass is 13%, and the reduction rate of the previous pass before entering the final rolling is reduced by 20%. The cooling water for rolling is reduced, and descaling is only performed once after roughing to obtain an 85mm rolled plate.

[0075] The 85mm rolled plate was straightened at point 4 on the feed rollers to ensure a flatness of 0.5mm / m. The straightened 85mm plate was then placed in a stacking rack, and the rack temperature was maintained at 560℃ for slow cooling treatment for 8 hours.

[0076] After slow cooling, the 85mm thick plate was heated at 1000℃ for 3 hours in a heating and finishing mechanism, held at that temperature for 3 hours, air-cooled to room temperature, and after an interval of 9 hours, it was tempered at 600℃ for 6 hours, held at that temperature for 5 hours, and then air-cooled a second time to obtain an 85mm thick 04Cr13Ni5Mo stainless steel plate.

[0077] The temperature control rolling process for 04Cr13Ni5Mo stainless steel plates given in Examples 1 to 5 above can all produce 04Cr13Ni5Mo stainless steel plates. The performance of the 04Cr13Ni5Mo stainless steel plates prepared in Examples 1 to 5 and Comparative Examples 1 to 5 is now tested, and the results are shown in Table 1.

[0078] Table 1. Mechanical property testing results of the hot-rolled dual-phase steels prepared in Examples 1 to 5 and Comparative Examples 1 to 5. Physicochemical testing Regarding precise temperature control, Examples 1 to 5 were heated at heating rates of 4℃ / min, 3℃ / min, 2℃ / min, 1℃ / min, and 5℃ / min, respectively, and homogenized at 1190℃~1210℃ for 2h~4h. The finishing rolling temperature was 950℃~1000℃ and the final rolling temperature was 850℃~920℃, with no thermal stress cracks. Comparative Examples 1 and 2 were heated to 1200℃ at a heating rate of 6℃ / min and homogenized for 1.5h, respectively, and 3 and 1 thermal stress cracks appeared, respectively, confirming that precise temperature control solves the problem of thermal stress cracks.

[0079] Regarding uniform deformation, Examples 1 to 5 all used a single-pass reduction rate of 12% to 15% for finishing rolling, and reduced the reduction amount of the last pass before final rolling by 20% to 25%, controlling the flatness of the rolled plate to 0.1 mm / m to 0.5 mm / m. UT flaw detection showed no internal porosity, and SEM images showed uniform grain size. In contrast, Comparative Example 3 had a single-pass reduction rate of 10% and no reduction in the reduction amount before final rolling, resulting in internal porosity and uneven grain size, confirming that uniform deformation solves the problem of uneven deformation.

[0080] Regarding slow cooling protection, the slow cooling temperature of stacked samples in Examples 1 to 5 was 550℃ to 590℃, and the slow cooling time was 8h to 10h, with no cooling cracks. However, in Comparative Example 4, which was naturally air-cooled, two cooling cracks appeared, confirming that slow cooling protection solves the problem of cooling cracking.

[0081] In terms of plasticity, the elongation of the stainless steel plates in Examples 1 to 5 was 23%, which met the plasticity standard. The elongation of the stainless steel plates in Comparative Examples 1 and 5 was 20%, which reduced the plasticity. Combined with the process parameters of Examples 1 to 5, it is confirmed that precise temperature control and uniform deformation work together to solve the problem of reduced plasticity.

[0082] (0) Elemental analysis The key element contents of the 04Cr13Ni5Mo steels in Examples 1-5 and Comparative Examples 1-5 all met the standards, with C ≤ 0.04%, Cr 12.0%~14.0%, Ni 4.0%~6.0%, Mo 0.40%~0.60%, and impurity elements such as Si and Mn ≤ 1.0%. All samples were of acceptable composition, with no element exceeding the standard or segregation, ruling out performance defects caused by composition issues. Performance differences were only caused by differences in parameters such as temperature control and reduction rate.

[0083] (1) UT flaw detection Examples 1 through 5 showed no internal defects detected by UT flaw detection, achieving a 100% pass rate. Comparative Example 1 showed two internal cracks, ranging from 0.5mm to 1.0mm in size, and Comparative Example 3 showed one internal porosity, ranging from 0.3mm to 0.8mm in size. The remaining comparative examples showed no internal defects. Precise temperature control and uniform deformation in the examples eliminated internal voids, while uneven heating in Comparative Example 1 and a reduction rate of less than 10% in Comparative Example 3 resulted in internal defects.

[0084] (2) Detection of elemental composition Consistent with the elemental analysis results, the C, Cr, Ni, and Mo contents of Examples 1-5 and Comparative Examples 1-5 all meet the national standard requirements for 04Cr13Ni5Mo steel, with no local element enrichment or deficiency. The elemental composition is stable and uniform. The yield strength ratio of Examples 1-5 is 0.8-0.85, with no excessive deformation, while the yield strength ratio of the comparative examples is <0.8, with large deformation. This further verifies that the performance difference between the examples and the comparative examples is due to process control rather than compositional fluctuations.

[0085] (3) SEM SEM images of Examples 1-5 show fine and uniform grains, with a size of 10μm-15μm and a regular distribution of martensite. Comparative Example 1 shows coarse grains, with a size of 20μm-25μm and localized martensite embrittlement; Comparative Example 3 shows uneven grains, with a size of 15μm-22μm; and Comparative Example 4 shows locally coarse martensite laths. These examples, through precise temperature control and reasonable reduction rates, avoided abnormal grain growth and achieved grain refinement. Comparative Examples 1-5, due to uneven heating, insufficient reduction rates, or lack of slow cooling, resulted in abnormal grain structures, thus affecting plasticity and processability.

[0086] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A rolling and temperature control process for 04Cr13Ni5Mo stainless steel plate, characterized in that, Includes the following steps: The pretreated stainless steel billet is heated to 1190℃~1210℃ at a heating rate of 0℃ / min < heating rate ≤ 5℃ / min, and homogenized at this temperature for ≥ 2 hours. During the entire heating and homogenization process, an inert gas is introduced to maintain a uniform protective atmosphere. The heated stainless steel billet is then subjected to rough rolling and multi-pass finishing rolling. The finishing rolling temperature is ≥ 950℃, and the final rolling temperature is 850℃~920℃. The single-pass reduction rate of each finishing rolling pass is 12%~15%, and the reduction rate of the previous pass before entering the final rolling is reduced by 20%~25% to obtain the rolled plate. The rolled plate was straightened and then placed in an environment with a temperature ≥550℃ for slow cooling for 8h~10h, and then naturally cooled to room temperature. The plate after slow cooling is subjected to normalizing and tempering heat treatment. The normalizing temperature is 1030℃~1050℃, heated for 8 hours, and the 85mm thick plate is held at the temperature for 4 hours and the 115mm thick plate is held at the temperature for 5 hours. After air cooling to room temperature, after an interval of 8 hours~10 hours, it is tempered at 610℃~630℃ for 6 hours~8 hours, the 85mm thick plate is held at the temperature for 6 hours and the 115mm thick plate is held at the temperature for 8 hours. After a second air cooling, 04Cr13Ni5Mo stainless steel plate is obtained.

2. The rolling and temperature control process for 04Cr13Ni5Mo stainless steel plate according to claim 1, characterized in that, The thickness of the stainless steel billet is ≥320mm.

3. The rolling and temperature control process for 04Cr13Ni5Mo stainless steel plate according to claim 1, characterized in that, 0 < Flatness of the straightened rolled plate ≤ 0.5 mm / m.

4. The rolling and temperature control process for 04Cr13Ni5Mo stainless steel plate according to claim 1, characterized in that, Pickling is used to remove the oxide scale from the surface of stainless steel billets, and qualified stainless steel billets are screened at the same time.

5. The rolling and temperature control process for 04Cr13Ni5Mo stainless steel plate according to claim 1, characterized in that, During rough rolling, the amount of cooling water and the number of descaling cycles after rough rolling are controlled to ensure that the heated stainless steel billet meets the requirement of a finishing rolling temperature of ≥950℃. During finishing rolling, the amount of cooling water is controlled to ensure that the final rolling temperature is 850℃~920℃.

6. A 04Cr13Ni5Mo stainless steel plate, characterized in that, It is manufactured using the rolling and temperature control process of 04Cr13Ni5Mo stainless steel plate as described in any one of claims 1 to 5.

7. The 04Cr13Ni5Mo stainless steel plate according to claim 6, characterized in that, The 04Cr13Ni5Mo stainless steel plate has a yield strength of 639 MPa, a tensile strength of 892.2 MPa, an elongation of 23%, and a hardness of HB277.

8. The 04Cr13Ni5Mo stainless steel plate according to claim 6, characterized in that, The yield strength ratio of the 04Cr13Ni5Mo stainless steel plate is 0.8~0.

85.

9. The 04Cr13Ni5Mo stainless steel plate according to claim 6, characterized in that, The processing deformation range of the 04Cr13Ni5Mo stainless steel plate is ≤1.2mm / m.

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