CN115138691A - High-grade surface control method for 316-series stainless steel cold-rolled strip steel production line - Google Patents
High-grade surface control method for 316-series stainless steel cold-rolled strip steel production line Download PDFInfo
- Publication number
- CN115138691A CN115138691A CN202210675544.2A CN202210675544A CN115138691A CN 115138691 A CN115138691 A CN 115138691A CN 202210675544 A CN202210675544 A CN 202210675544A CN 115138691 A CN115138691 A CN 115138691A
- Authority
- CN
- China
- Prior art keywords
- roller
- thickness
- stainless steel
- rolled strip
- roughness
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
- C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
- C23G1/08—Iron or steel
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
- C25F1/00—Electrolytic cleaning, degreasing, pickling or descaling
- C25F1/02—Pickling; Descaling
- C25F1/04—Pickling; Descaling in solution
- C25F1/06—Iron or steel
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Physics & Mathematics (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Metal Rolling (AREA)
Abstract
The invention relates to the field of stainless steel cold-rolled strip steel production, in particular to a high-grade surface control method for a 316 series stainless steel cold-rolled strip steel production line, which comprises the following steps: the first part is a rolling mill part; the second part is a heat treatment part; the third part is an acid washing part; the fourth part is a flat part; and the fifth part is the management of the full-line strip steel channel. The first-time qualified rate of the 316-series high-grade surface stainless steel on the continuous rolling production line is improved from 47% to 99.8%. And unqualified products are reduced.
Description
Technical Field
The invention relates to the field of stainless steel cold-rolled strip steel production, which comprises surface control, lubrication, full-line tension matching of a cold line unit, a heat treatment process, an acid washing model and a leveling process of a 5-rack 6-roller cold continuous rolling mill, in particular to a high-grade surface control method of a 316-series stainless steel cold-rolled strip steel production line.
Background
A cold-rolled strip steel full-continuous production line (called RAP line for short in English, hereinafter, the RAP line is used for replacing the full-continuous production line) of a Shanxi Tai steel stainless steel cold rolling mill integrates 6 working procedures of a cold continuous rolling mill, an annealing furnace, an acid washing machine, a temper mill, a tension leveler, a trimming shear and the like into one production line, and a finished product can be directly delivered to a user after the product is taken off line.
When the RAP wire is used for producing 316 series high-grade surface stainless steel, due to special requirements on surface roughness, consistency and the like of products, after rolling, annealing, pickling and leveling, the roughness fluctuation of the existing process system is large, and the steel coil with unqualified roughness reaches 44%. In addition, large-scale production lines have more rollers and long strip steel channels, so that mechanical defects such as surface bumps and pits are easily caused, defects such as surface slipping and scratching caused by unmatched tension and surface pollution of the strip steel are easily caused, the consistency is poor, unqualified steel coils reach 11%, and the use requirements and delivery requirements of customers cannot be met.
According to different specifications, different roll configurations, tension models, heating models, pickling models and leveling models are formulated, high-precision control of the surface of the full-line steel strip is achieved, and the use requirements that the roughness of a finished product meets 0.09-0.12 mu m, the surface has no concave-convex points and the pickled surface is uniform and consistent are met.
Disclosure of Invention
The invention aims to solve the problems and provides a high-grade surface control method for a 316-series stainless steel cold-rolled strip steel production line.
The purpose of the invention is realized by the following steps: a high-grade surface control method for a 316 series stainless steel cold-rolled strip steel production line comprises the following steps: the first part is a rolling mill part, the 316 series stainless steel cold-rolled strip steel rolling surface is controlled, and special process design is carried out through special configuration of roller roughness and rolling lubricating liquid concentration configuration; the second part is a heat treatment part, and the 316 series stainless steel cold-rolled strip steel cannot be excessively oxidized in the heat treatment process, otherwise, the results of thicker surface iron scale and difficult pickling can be caused, and meanwhile, the surface is bluish due to excessively light oxidation; annealing and heating are carried out in an environment with 3.5-5% of oxygen content after the temperature of the steel plate exceeds 980 ℃, and the time is not more than 12s; the third part is an acid washing part, and the process design is carried out from two aspects of electrolytic acid washing and mixed acid washing; sodium sulfate electrolysis belongs to neutral salt electrolysis, iron scales on the surface of a steel strip are removed by means of electrochemical reaction, due to the particularity of a surface oxide skin after heat treatment, 30s of electrolysis before the neutral salt electrolysis needs to be carried out for a large time, the electrolysis efficiency is ensured, the electrolysis current is 4500A-4700A, then the electrolysis is carried out in cooperation with 7-13s of small current, the ferrous oxide on the bottommost layer of the oxide skin can be uniformly peeled, and the electrolysis current is controlled to be 1800-2200A; the mixed acid pickling part is divided into 2 groove bodies, wherein the first groove body is high in concentration, and the second groove body is low in concentration; the concentrations of nitric acid and hydrofluoric acid in the 1 st tank body are respectively as follows: 140-180g/l,16-22g/l; the concentration of the nitric acid and the hydrofluoric acid in the 2 nd tank body are respectively as follows: 120-150g/l,12-18g/l; the fourth part is a flat part, a polishing roller is adopted as the flat roller, and the roughness is 0.08-0.12 μm; controlling the pressure and the elongation of the temper mill, and designing different elongations according to different thickness specifications so as to ensure the consistency of surface roughness; the fifth part is the management of the full-line strip steel channel; the tension of the furnace is matched with the tension of acid washing, so that the tension roller of the idle running section can be prevented from slipping, roller ways such as a drying roller, a tension roller, a deviation correction roller and the like of the whole line are subjected to regular inspection wiping and periodic replacement, and foreign matters on the surface are cleaned and removed.
Roll roughness in the mill section: according to the deformation of 5 frames, the steel is respectively used on 5 frames according to the deformation of 1.2 μm, 1.1 μm, 0.8 μm, 0.3 μm and 0.11 μm, and the roughness range of a roller is +/-0.02 μm; the concentration of the rolling lubricating liquid of the first 3 stands is configured to be 3% -3.5%, so that sufficient lubrication of the surface is ensured in the low-speed rolling process, and surface defects in the raw materials are eliminated; the concentration of the rolling lubricating liquid of the 4# and 5# frames is configured to be 1.8-2.2%, so that the phenomenon of skidding is avoided in the high-speed rolling process, and meanwhile, a boundary lubrication state is formed in a deformation area in the rolling process, so that the surface roughness of the rolled steel plate can reach 0.12-0.15 mu m.
Designing different elongation rates in the flattening part according to different thickness specifications so as to ensure that the surface roughness is consistent, specifically, the elongation rate of the finished product with the thickness of 2.0-3.0mm is controlled according to 0.55-0.65%; the elongation of the finished product with the thickness of 1.2-1.8mm is controlled according to 0.45-0.51%; the elongation of the finished product with the thickness of 0.8-1.1mm is controlled according to 0.35-0.41 percent.
When the heat treatment part meets specification change, namely the thickness of the material changes, the speed of an annealing furnace and the heating time of the material change, the temperature of a furnace area is adjusted in time according to the requirement of the thickness specification, the time for heating the material to be higher than 980 ℃ is 7-12s according to the thickness multiplied by the speed, namely the TV value is 95 +/-10, and the time for heating the material to be higher than 980 ℃ is 7-12s when the corresponding thickness is thickened, the temperature of the first 14 furnace areas is controlled to be 980-1010 ℃, so that the time of the material in the furnace is prolonged, and conversely, when the thickness of the material is thinned, the time for heating the material to be higher than 980 ℃ is 7-12s, the temperature of the first 14 furnace areas is controlled to be 1010-1120 ℃, so that the time of the material in the furnace is shortened, and excessive oxidation is avoided.
The beneficial effects of the invention are: 1. the first-time qualified rate of the 316-series high-grade surface stainless steel on the continuous rolling production line is improved from 47% to 99.8%. And unqualified products are reduced.
2. The roughness and the consistency completely meet the processing requirements of customers.
3. According to the process characteristics of rolling, heat treatment, acid cleaning and flattening of materials with different specifications, the process procedures of 316 stainless steel cold-rolled strip steels with different specifications are refined.
4. Ensuring that the roughness of the finished product meets 0.09 to 0.12 mu m.
Detailed Description
The technical scheme of the invention is as follows:
the first part is a rolling mill part, 316 is stainless steel cold-rolled strip steel rolling surface control, and special process design is carried out through special configuration of roller roughness and rolling lubricating liquid concentration configuration.
1. The roll roughness was 1.2 μm, 1.1 μm, 0.8 μm, 0.3 μm, and 0.11 μm in each of 5 stands in accordance with the amount of deformation of the 5 stands, and the range of the roll roughness was. + -. 0.02. Mu.m.
2. The concentration of the rolling lubricating liquid of the first 3 stands is configured to be 3% -3.5%, so that sufficient lubrication of the surface is guaranteed in the low-speed rolling process, and surface defects in the raw materials are eliminated. The concentration of the rolling lubricating liquid of the 4# and 5# frames is configured to be 1.8-2.2%, so that the phenomenon of slipping is avoided in the high-speed rolling process, and meanwhile, a boundary lubrication state is formed in a deformation area in the rolling process, so that the surface roughness of the rolled steel plate can reach 0.12-0.15 mu m.
The second part is a heat treatment part, and the 316 series stainless steel cold-rolled strip steel cannot be excessively oxidized in the heat treatment process, otherwise, the results of thick surface scale and difficult pickling can be caused, and the surface is blued due to excessively light oxidation. After the temperature of the steel plate exceeds 980 ℃, annealing and heating are carried out in an environment with the oxygen content of 3.5-5%, and the time is not more than 12s.
1. When the specification changes, the speed of the annealing furnace and the heating time of the material can change, the temperature of the furnace area can be adjusted in time according to the specification requirement, and the excessive oxidation is avoided. When the specific heat treatment part meets specification change, namely the thickness of a material changes, the speed of an annealing furnace and the heating time of the material can change, the temperature of a furnace zone can be adjusted in time according to the requirement of the thickness specification, the time of the heating temperature of the material higher than 980 ℃ can reach 7-12s according to the thickness multiplied by the speed, namely the TV value is 95 +/-10, the time of the heating temperature of the material higher than 980 ℃ can reach 7-12s when the corresponding thickness becomes thick, the time of the heating temperature of the material higher than 980 ℃ is ensured to be 7-12s, the temperature of the first 14 furnace zones is controlled to be 980-1010 ℃, so that the time of the material in the furnace can be prolonged, and conversely, when the thickness of the material becomes thin, the time of the heating temperature of the material higher than 980 ℃ is ensured to be 7-12s, the temperature of the first 14 furnace zones is controlled to be 1010-1120 ℃, so that the time of the material in the furnace can be shortened, and excessive oxidation can be ensured not occur.
2. In the annealing furnace, the surface of the steel strip can contact with the furnace bottom roller, cracks and protrusions cannot be formed on the surface of the furnace bottom roller, and the steel strip is guaranteed not to generate mechanical defects such as salient points, crack prints and the like.
The third part is an acid washing part, and 316 is difficult to wash due to Mo, so that the process design is needed from two aspects of electrolytic acid washing and mixed acid washing.
1. Sodium sulfate electrolysis belongs to neutral salt electrolysis, iron scale on the surface of a steel strip is removed mainly by means of electrochemical reaction, and due to the particularity of surface oxide skin after heat treatment, 30 seconds before neutral salt electrolysis needs to be greatly electrolyzed to ensure the electrolysis efficiency, and the electrolysis current is 4500A to 4700A. Then, the electrolysis is carried out for 10 seconds, so that the ferrous oxide at the bottommost layer of the oxide scale can be uniformly peeled, otherwise, the non-uniform corrosion of the mixed acid can be caused, and the electrolysis current is controlled to be 2000A.
2. And the mixed acid pickling part is divided into 2 tank bodies, wherein the first tank body has high concentration, and the second tank body has low concentration. The concentration of nitric acid and hydrofluoric acid in the 1 st tank body are respectively as follows: 140 to 180g/l, and 16 to 22g/l. The concentration of nitric acid and hydrofluoric acid in the 2 nd tank body are respectively as follows: 120 to 150g/l,12 to 18g/l. And through mixed acid corrosion and passivation, the surface is ensured not to be excessively corroded and the roughness is increased. Because the thicknesses of the materials are different and the process TV value is the same, after acid washing, the surface roughness is slightly different, the roughness of the thick specification material is large, the roughness of the thin specification material is small, and the roughness needs to be improved by a flattening machine.
The fourth part is the leveling part and the leveler is the last item of surface roughness control. The leveling roller is a polishing roller with the roughness of 0.1 μm.
1. The pressure and the elongation of the temper mill need to be controlled, and different elongation designs are carried out according to different thickness specifications, so that the consistency of the surface roughness is ensured.
2. The elongation of the material is controlled according to the thickness of the finished product of 2.0 to 3.0mm and 0.55 to 0.65 percent.
3. The elongation of the material is controlled according to the thickness of the finished product of 1.2 to 1.8mm and is controlled according to the elongation of 0.45 to 0.51 percent.
4. The elongation of the material is controlled according to 0.35 to 0.41 percent according to the thickness of a finished product of 0.8 to 1.1 mm.
The fifth part is the whole-line strip steel channel management. The tension of the furnace is matched with the tension of the pickling, so that the tension roller of the idle running section can be prevented from slipping.
1. And (4) performing regular inspection wiping and periodic replacement on roller beds such as the full-line drying roller, the tension roller, the deviation correction roller and the like. And cleaning and removing foreign matters on the surface.
The scheme is applied to continuous rolling of No. 2 RAP lines in a stainless-steel cold rolling plant, the running time is more than 1 year, the process and program design stably run, and the using effect is good.
The above description is only an embodiment of the present invention, but the structural features of the present invention are not limited thereto, and any changes or modifications within the scope of the present invention by those skilled in the art are covered by the present invention.
Claims (4)
1. A high-grade surface control method for a 316 series stainless steel cold-rolled strip steel production line is characterized by comprising the following steps: the method comprises the following steps:
the first part is a rolling mill part, the 316 series stainless steel cold-rolled strip steel rolling surface is controlled, and special process design is carried out through special configuration of roller roughness and rolling lubricating liquid concentration configuration;
the second part is a heat treatment part, and the 316 series stainless steel cold-rolled strip steel cannot be excessively oxidized in the heat treatment process, otherwise, the results of thicker surface iron scale and difficult pickling can be caused, and meanwhile, the surface is bluish due to excessively light oxidation; annealing and heating are carried out in an environment with 3.5-5% of oxygen content after the temperature of the steel plate exceeds 980 ℃, and the time is not more than 12s;
the third part is an acid washing part, and the process design is carried out from two aspects of electrolytic acid washing and mixed acid washing; sodium sulfate electrolysis belongs to neutral salt electrolysis, iron scales on the surface of a steel strip are removed by means of electrochemical reaction, due to the particularity of a surface oxide skin after heat treatment, 30s of electrolysis before the neutral salt electrolysis needs to be carried out for a large time, the electrolysis efficiency is ensured, the electrolysis current is 4500A-4700A, then the electrolysis is carried out in cooperation with 7-13s of small current, the ferrous oxide on the bottommost layer of the oxide skin can be uniformly peeled, and the electrolysis current is controlled to be 1800-2200A; the mixed acid pickling part is divided into 2 groove bodies, wherein the first groove body is high in concentration, and the second groove body is low in concentration; the concentration of nitric acid and hydrofluoric acid in the 1 st tank body are respectively as follows: 140-180g/l,16-22g/l; the concentration of the nitric acid and the hydrofluoric acid in the 2 nd tank body are respectively as follows: 120-150g/l,12-18g/l;
the fourth part is a flat part, a polishing roller is adopted as the flat roller, and the roughness is 0.08-0.12 μm; controlling the pressure and the elongation of the temper mill, and designing different elongations according to different thickness specifications so as to ensure the consistency of surface roughness;
the fifth part is the management of the full-line strip steel channel; the tension of the furnace is matched with the tension of acid washing, so that the tension roller of the idle running section can be prevented from slipping, roller ways such as a drying roller, a tension roller, a deviation correction roller and the like of the whole line are subjected to regular inspection wiping and periodic replacement, and foreign matters on the surface are cleaned and removed.
2. The high-grade surface control method for the 316 series stainless steel cold-rolled strip steel production line according to claim 1, characterized by comprising the following steps of: roll roughness in the mill section: according to the deformation of 5 frames, the roller is respectively used on 5 frames according to 1.2 μm, 1.1 μm, 0.8 μm, 0.3 μm and 0.11 μm, and the roughness range of the roller is +/-0.02 μm; the concentration of the rolling lubricating liquid of the first 3 stands is configured to be 3% -3.5%, so that sufficient lubrication of the surface is ensured in the low-speed rolling process, and surface defects in the raw materials are eliminated; the concentration of the rolling lubricating liquid of the 4# and 5# frames is configured to be 1.8-2.2%, so that the phenomenon of skidding is avoided in the high-speed rolling process, and meanwhile, a boundary lubrication state is formed in a deformation area in the rolling process, so that the surface roughness of the rolled steel plate can reach 0.12-0.15 mu m.
3. The high-grade surface control method for the 316 series stainless steel cold-rolled strip steel production line according to claim 1, characterized by comprising the following steps of: designing different elongation rates in the flattening part according to different thickness specifications so as to ensure that the surface roughness is consistent, specifically, the elongation rate of the finished product with the thickness of 2.0-3.0mm is controlled according to 0.55-0.65%; the elongation of the finished product with the thickness of 1.2-1.8mm is controlled according to 0.45-0.51%; the elongation of the finished product with the thickness of 0.8-1.1mm is controlled according to 0.35-0.41%.
4. The high-grade surface control method of the 316 series stainless steel cold-rolled strip steel production line according to claim 1, wherein the method comprises the following steps: when the heat treatment part meets specification change, namely the thickness of the material changes, the speed of an annealing furnace and the heating time of the material change, the temperature of a furnace area is adjusted in time according to the requirement of the thickness specification, the time for heating the material to be higher than 980 ℃ is 7-12s according to the thickness multiplied by the speed, namely the TV value is 95 +/-10, and the time for heating the material to be higher than 980 ℃ is 7-12s when the corresponding thickness is thickened, the temperature of the first 14 furnace areas is controlled to be 980-1010 ℃, so that the time of the material in the furnace is prolonged, and conversely, when the thickness of the material is thinned, the time for heating the material to be higher than 980 ℃ is 7-12s, the temperature of the first 14 furnace areas is controlled to be 1010-1120 ℃, so that the time of the material in the furnace is shortened, and excessive oxidation is avoided.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210675544.2A CN115138691A (en) | 2022-06-15 | 2022-06-15 | High-grade surface control method for 316-series stainless steel cold-rolled strip steel production line |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210675544.2A CN115138691A (en) | 2022-06-15 | 2022-06-15 | High-grade surface control method for 316-series stainless steel cold-rolled strip steel production line |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115138691A true CN115138691A (en) | 2022-10-04 |
Family
ID=83408461
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210675544.2A Pending CN115138691A (en) | 2022-06-15 | 2022-06-15 | High-grade surface control method for 316-series stainless steel cold-rolled strip steel production line |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115138691A (en) |
-
2022
- 2022-06-15 CN CN202210675544.2A patent/CN115138691A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| AU716533B2 (en) | Process for the continuous production of a rolled stainless steel sheet strip and continuous production line for carrying out the process | |
| CN108097720B (en) | Rolling process of pure titanium cold-rolled thin titanium strip with width of 1250mm | |
| CN108165822B (en) | Preparation method of TA2 cold-rolled titanium strip for low-strength and easy-to-form welded pipe | |
| CN105689392A (en) | Production method for ultra-thin cold-rolled enamelled steel strips | |
| CN1319660C (en) | High-precision very-thin special-wide cold-rolled steel band and its working process | |
| CN111014315B (en) | Method for improving surface reflectivity of rolled hard coil strip steel | |
| CN105251779B (en) | A kind of hot rolling acid-cleaning plate surface oxidation point defects controlling method | |
| CN107052060A (en) | A kind of method for eliminating acid-cleaning plate Pinhole-shaped pit defect | |
| CN109622613A (en) | The processing method of 201 cold rolled stainless steel bands | |
| CN113664037A (en) | Production method of cold-rolled IF steel with high surface cleanliness | |
| CN114107622B (en) | Production method of cold-rolled nickel-saving austenitic stainless steel 8K mirror surface | |
| CN103100562B (en) | Method of machining special passivated stainless steel surface | |
| CN115138691A (en) | High-grade surface control method for 316-series stainless steel cold-rolled strip steel production line | |
| CN111515257B (en) | Method for controlling rolling stripe color difference defect of stainless steel wide bright plate | |
| CN107252821A (en) | A kind of hot-rolled structural steel production method that can avoid producing the black steel defect of pickling | |
| CN209647212U (en) | A kind of Cold Rolling System of stainless steel band | |
| CN109530433B (en) | Cold rolling system of stainless steel strip | |
| CN115261582A (en) | Production method of special cold-rolled steel strip for economical anti-aging electrogalvanizing substrate | |
| CN103272841B (en) | Cold rolling technology of stainless steel clad plate strip coil | |
| CN105149348A (en) | Method of producing TA10 alloy rolls through twenty-roller cold rolling unit | |
| CN114682643A (en) | Production process of ultrathin copper strip | |
| CN115121625A (en) | Surface control method for stainless steel cold-rolled strip steel production line for automobile exhaust system | |
| CN111041351A (en) | Production method of high-surface acid-washing product capable of being used as electroplating substrate | |
| CN114055082B (en) | Production method of high-grade special steel precision steel strip for crochet hook | |
| CN114908288B (en) | Super-thick hot-rolled pickled plate and preparation method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |