A process for removing surface defects from 4J42 constant expansion precision alloy by hot rolling
By combining rough rolling, softening heat treatment, multi-pass wire drawing, and texturing roll cold rolling, the problem of pitting and white spot defects on the surface of 4J42 constant expansion precision alloy was solved, achieving efficient and low-cost surface defect removal. It is applicable to other low-alloy precision alloys that are prone to surface selective oxidation defects.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 江苏圣珀新材料科技有限公司
- Filing Date
- 2026-02-10
- Publication Date
- 2026-05-26
AI Technical Summary
Existing technologies cannot completely remove pits and white spots on the surface of 4J42 constant expansion precision alloy, resulting in low production efficiency, high material loss, and high processing costs.
The process employs a combination of rough rolling and softening heat treatment, soft multi-pass wire drawing treatment, and texturing roll cold rolling finishing. First, the strip is transformed into a soft state. Then, the oxide layer defects are removed through multi-pass sanding wire drawing treatment and sanding with a specific mesh size. Finally, texturing roll rolling is used to obtain a uniform and consistent finished product surface.
It achieves efficient removal of surface defects, simplifies the production process, reduces energy consumption and auxiliary material consumption, and improves production efficiency and cost-effectiveness.
Smart Images
Figure CN122076822A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of precision alloy processing technology, specifically a process for removing hot-rolled defects on the surface of 4J42 constant expansion precision alloy. Background Technology
[0002] 4J42 constant expansion precision alloy is widely used in electronic vacuum devices, packaging, and other fields due to its coefficient of thermal expansion matching that of hard glass and ceramics within a specific temperature range. However, because the content of elements that improve oxidation resistance, such as Cr, Si, and Al, in this alloy is low, it is prone to selective oxidation during heating and holding in the furnace, forming a thick and loose outer and inner oxide layer on the surface. The coefficient of thermal expansion of this oxide layer differs significantly from that of the alloy matrix, making it easy to detach from the matrix during subsequent cooling and hot rolling. The detached oxide particles are pressed into the alloy surface during rolling, forming pitted white spot defects, which seriously affect the appearance, sealing performance, and subsequent plating quality of the product.
[0003] Traditional methods for addressing these defects mainly rely on overall grinding or multiple pickling of hot-rolled slabs, but these methods suffer from low production efficiency, high material consumption, severe environmental pollution, and difficulty in completely removing surface defects. Summary of the Invention
[0004] The purpose of this invention is to provide a hot-rolling defect removal process for the surface of 4J42 constant expansion precision alloy, in order to solve the problems of existing processes being unable to completely remove pits and white spots on the surface, resulting in low production efficiency, large material loss, and high processing costs.
[0005] To achieve the above objectives, the present invention adopts the following technical solution: a process for removing surface defects from 4J42 constant expansion precision alloy by hot rolling, comprising the following steps:
[0006] S1. Rough rolling and softening heat treatment: The hot-rolled 4J42 alloy billet is cold-rolled to an intermediate thickness, and then softening heat treatment is performed in a protective atmosphere or air to transform the cold-rolled strip into a soft state. At this time, the surface oxidation defects generated by hot rolling on the surface of the 4J42 alloy billet are transformed into white spots on the edge of the soft strip.
[0007] S2. Soft state multi-pass wire drawing treatment: The soft strip after softening heat treatment is subjected to at least two abrasive belt wire drawing treatments, and the mesh size of the abrasive belt used in the latter wire drawing is higher than that in the former, in order to remove the white spots on the edge and make the wire drawing marks on the surface of the soft strip uniform.
[0008] S3. Texturizing roll cold rolling finishing: The strip after wire drawing is cold rolled in multiple passes to the finished thickness, wherein at least in the first two rolling passes, texturizing rolls are used to eliminate the wire drawing marks and obtain a uniform finished surface.
[0009] As a further description of the above technical solution:
[0010] In step S1, the intermediate thickness is 1.6mm-2.0mm.
[0011] As a further description of the above technical solution:
[0012] In step S1, the working conditions for the softening heat treatment are: continuous annealing at a temperature of 1000℃-1100℃ and a speed of 1-3m / min.
[0013] As a further description of the above technical solution:
[0014] Before the cold rough rolling in step S1, the pretreatment step of pickling or shot blasting the hot-rolled 4J42 alloy billet is also included.
[0015] As a further description of the above technical solution:
[0016] In step S2, the abrasive belt drawing process is performed twice: the first drawing uses a combination of 80-mesh and 120-mesh abrasive belts in sequence; the second drawing uses a combination of 120-mesh and 180-mesh abrasive belts in sequence.
[0017] As a further description of the above technical solution:
[0018] In step S3, the cold rolling process includes 8 passes, with rolling thicknesses of 1.8mm, 1.6mm, 1.4mm, 1.24mm, 1.1mm, 0.98mm, 0.88mm, and 0.8mm respectively.
[0019] As a further description of the above technical solution:
[0020] In step S3, the surface roughness Ra of the texturing roller is 0.8-1.2 μm.
[0021] As a further description of the above technical solution:
[0022] In step S3, the total processing deformation of the multi-pass cold rolling is 50%-60%.
[0023] In summary, due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art:
[0024] This invention addresses the problem of pits and white spots easily appearing on the surface of 4J42 constant expansion precision alloy after hot rolling. It proposes an innovative removal process, the core of which involves: first, softening the strip through heat treatment to transform it into a soft state; then, leveraging the good ductility and ease of large-volume uniform processing of the soft material, performing multi-pass, specific-mesh abrasive strip drawing to thoroughly remove and homogenize the loose, easily detachable oxide layer and surface defects. Following this, in the subsequent cold rolling thinning process, especially in the first few passes, a texturing roll with a specific roughness is used to further flatten the uniform surface texture after drawing, transforming it into a uniform finished surface. Through the combination of soft-state drawing, multi-pass cold rolling, and initial texturing roll rolling, a defect-free, high-quality finished product is ultimately achieved, improving the defect removal effect. This process avoids the traditional billet grinding process, simplifies the production flow, reduces energy and auxiliary material consumption, and improves production efficiency and cost-effectiveness. The principle of this process has important reference and promotion value for the surface treatment of other low-alloy precision alloys (such as 4J36, 4J50, etc.) that are prone to surface selective oxidation defects, and has a certain degree of universality. Attached Figure Description
[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0026] Figure 1 This is a flowchart of a hot-rolling defect removal process for the surface of a 4J42 constant expansion precision alloy.
[0027] Figure 2 This is a physical image of the soft strip (white spot on the edge) in step S1 of a hot rolling defect removal process for a 4J42 constant expansion precision alloy.
[0028] Figure 3 This is a photograph of the soft strip after the first wire drawing in step S2 of a hot rolling defect removal process for 4J42 constant expansion precision alloy.
[0029] Figure 4 This is a photograph of the soft strip after the second wire drawing in step S2 of a hot rolling defect removal process for 4J42 constant expansion precision alloy.
[0030] Figure 5 This is a physical image of a 4J42 constant expansion precision alloy surface hot rolling defect removal process, specifically the texturing roll rolling in step S3.
[0031] Figure 6This is a physical image of the finished product after multiple cold rolling passes in step S3 of a hot rolling defect removal process for the surface of a 4J42 constant expansion precision alloy. Detailed Implementation
[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0033] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.
[0034] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0035] In the description of the embodiments of the present invention, it should be noted that the terms "upper" and "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.
[0036] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection, an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0037] Example 1:
[0038] Please see Figure 1-6 This invention provides a technical solution: a process for removing surface defects from 4J42 constant expansion precision alloy by hot rolling, comprising the following steps:
[0039] S1. Rough rolling and softening heat treatment: The incoming material is a 3.5mm thick 4J42 hot-rolled black steel coil. The hot-rolled 4J42 alloy billet is cold rough rolled to an intermediate thickness, wherein the intermediate thickness is 1.6mm-2.0mm, preferably 1.8mm.
[0040] Subsequently, a softening heat treatment is performed in a protective atmosphere or air. Specifically, continuous annealing is carried out in a continuous annealing furnace at a temperature of 1000℃-1100℃ and a speed of 1-3 m / min, preferably at 1060℃ and a speed of 2 m / min, so that the cold-rolled strip is transformed into a soft state with a Vickers hardness (HV) of approximately 130-150. At this time, the surface oxidation defects generated by hot rolling of the 4J42 alloy billet are transformed into edge white spots of the soft strip. Specifically, it is observed that the inconspicuous indentation defects on the original surface appear as continuous or discontinuous white spots at the edges, such as... Figure 2 As shown;
[0041] S2. Soft-state multi-pass wire drawing treatment: The softened heat-treated strip is subjected to at least two abrasive belt drawing treatments, with the mesh size of the abrasive belt used in the later drawing being higher than that in the earlier drawing, to remove the white spots on the edges and make the wire drawing marks on the surface of the soft strip uniform and consistent; the abrasive belt drawing treatment is performed twice, and it can be wet or dry drawing. Specifically, the first drawing uses a wet drawing machine, using 80-mesh and 120-mesh abrasive belts sequentially for drawing. After the first drawing, the soft strip is as follows: Figure 3 As shown; next, a second fine drawing process is performed using 120-mesh and 180-mesh abrasive belts. After this step, the white spots on the surface completely disappear, revealing uniform, fine, straight fibers, as shown in the image. Figure 4 As shown; using soft wire drawing makes the surface drawing of 4J42 constant expansion precision alloy with a large amount of surface defect removal more uniform;
[0042] S3. Texturized Roll Cold Roll Finishing: The drawn strip is cold rolled in multiple passes to the finished thickness. At least in the first two rolling passes, texturized rolls are used to eliminate the drawing marks and obtain a uniform finished surface, ultimately achieving defect removal. Specifically, the 1.8mm thick drawn strip is cold rolled in 8 passes to a target thickness of 0.8mm. The specific rolling passes are: 1.8mm → 1.6mm → 1.4mm → 1.24mm → 1.1mm → 0.98mm → 0.88mm → 0.8mm. At least the first pass (1.8 → 1.6mm) and the second pass (1.6 → 1.4mm) use texturized work rolls with a surface roughness Ra of 0.8-1.2μm, preferably 1.0μm. For example... Figure 5As shown, annealed wire drawing is used, followed by subsequent cold rolling. A 1.0μm texturing roll is used to treat the surface, ensuring efficient surface homogenization and resolving defects inherent in the hot-rolled slab. Subsequent passes use conventional smooth rolls. The total deformation of the multi-pass cold rolling is 50%-60%, preferably 55.56%, and the rolled product is as follows... Figure 6 As shown.
[0043] Finally, finished product inspection is carried out: the surface of the rolled 0.8mm finished strip is bright and uniform, without any white spots, pits or visible wire marks, which fully meets the requirements of high-end applications, while reducing grinding processes, improving production efficiency and saving costs.
[0044] Example 2:
[0045] Please see Figure 1 The figure illustrates a hot-rolling defect removal process for 4J42 constant expansion precision alloy provided in Embodiment 2 of the present invention. Based on the above embodiments, this embodiment further improves upon the following technical solution: Before the cold rough rolling in step S1, a pretreatment step of pickling or shot blasting is included on the hot-rolled 4J42 alloy billet. Before cold rough rolling, some of the oxide scale on the surface of the billet is removed through pretreatment such as pickling.
[0046] In summary, due to the adoption of the above technical solution, the hot rolling defect removal process for 4J42 constant expansion precision alloy in this embodiment has the following advantages compared with the prior art:
[0047] This invention addresses the problem of pits and white spots easily appearing on the surface of 4J42 constant expansion precision alloy after hot rolling. It proposes an innovative removal process, the core of which involves: first, softening the strip through heat treatment to transform it into a soft state; then, leveraging the good ductility and ease of large-volume uniform processing of the soft material, performing multi-pass, specific-mesh abrasive strip drawing to thoroughly remove and homogenize the loose, easily detachable oxide layer and surface defects. Following this, in the subsequent cold rolling thinning process, especially in the first few passes, a texturing roll with a specific roughness is used to further flatten the uniform surface texture after drawing, transforming it into a uniform finished surface. Through the combination of soft-state drawing, multi-pass cold rolling, and initial texturing roll rolling, a defect-free, high-quality finished product is ultimately achieved, improving the defect removal effect. This process avoids the traditional billet grinding process, simplifies the production flow, reduces energy and auxiliary material consumption, and improves production efficiency and cost-effectiveness. The principle of this process has important reference and promotion value for the surface treatment of other low-alloy precision alloys (such as 4J36, 4J50, etc.) that are prone to surface selective oxidation defects, and has a certain degree of universality.
[0048] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A process for removing surface defects from 4J42 constant expansion precision alloy by hot rolling, characterized in that, Includes the following steps: S1. Rough rolling and softening heat treatment: The hot-rolled 4J42 alloy billet is cold-rolled to an intermediate thickness, and then softening heat treatment is performed in a protective atmosphere or air to transform the cold-rolled strip into a soft state. At this time, the surface oxidation defects generated by hot rolling on the surface of the 4J42 alloy billet are transformed into white spots on the edge of the soft strip. S2. Soft state multi-pass wire drawing treatment: The soft strip after softening heat treatment is subjected to at least two abrasive belt wire drawing treatments, and the mesh size of the abrasive belt used in the latter wire drawing is higher than that in the former, in order to remove the white spots on the edge and make the wire drawing marks on the surface of the soft strip uniform. S3. Texturizing roll cold rolling finishing: The strip after wire drawing is cold rolled in multiple passes to the finished thickness, wherein at least in the first two rolling passes, texturizing rolls are used to eliminate the wire drawing marks and obtain a uniform finished surface.
2. The process for removing surface defects of 4J42 constant expansion precision alloy by hot rolling according to claim 1, characterized in that, In step S1, the intermediate thickness is 1.6mm-2.0mm.
3. The process for removing surface defects of 4J42 constant expansion precision alloy by hot rolling according to claim 1, characterized in that, In step S1, the working conditions for the softening heat treatment are: continuous annealing at a temperature of 1000℃-1100℃ and a speed of 1-3m / min.
4. The process for removing surface defects of 4J42 constant expansion precision alloy by hot rolling according to claim 1, characterized in that, Before the cold rough rolling in step S1, the pretreatment step of pickling or shot blasting the hot-rolled 4J42 alloy billet is also included.
5. The process for removing surface defects of 4J42 constant expansion precision alloy by hot rolling according to claim 1, characterized in that, In step S2, the abrasive belt drawing process is performed twice: the first drawing uses a combination of 80-mesh and 120-mesh abrasive belts in sequence; the second drawing uses a combination of 120-mesh and 180-mesh abrasive belts in sequence.
6. The process for removing surface defects of 4J42 constant expansion precision alloy by hot rolling according to claim 1, characterized in that, In step S3, the cold rolling process includes 8 passes, with rolling thicknesses of 1.8mm, 1.6mm, 1.4mm, 1.24mm, 1.1mm, 0.98mm, 0.88mm, and 0.8mm respectively.
7. The process for removing surface defects of 4J42 constant expansion precision alloy by hot rolling according to claim 1, characterized in that, In step S3, the surface roughness Ra of the texturing roller is 0.8-1.2 μm.
8. The process for removing surface defects of 4J42 constant expansion precision alloy by hot rolling according to claim 1, characterized in that, In step S3, the total processing deformation of the multi-pass cold rolling is 50%-60%.