Surface processing method for corrosion-resistant alloy plate

Abstract

The application discloses a surface processing method of corrosion-resistant alloy plate, which comprises the following steps: S1, heating a plate blank; S2, rolling the heated plate blank into a plate; S3, heat treating and quenching the plate; S4, performing shot blasting treatment on the plate after the heat treatment and quenching; S5, performing preliminary inspection on the plate after the shot blasting, preliminarily grinding defects of the plate, and detecting whether the number or area of single-side defects of the plate exceeds a threshold value; if the number or area of single-side defects of the plate does not exceed the threshold value, a first process is performed; if the number or area of single-side defects of the plate exceeds the threshold value, a second process is performed; whether the number or area of single-side defects of the plate exceeds the threshold value is used to determine which process the plate enters; different processing methods are adopted according to the defect degree of the plate, the risk of over pickling of corrosion-resistant alloy 800 series plates in the pickling process is greatly reduced, and the shot blasting and pickling qualified rate of the corrosion-resistant alloy plate is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of corrosion-resistant alloy plates, in particular to a surface processing method of corrosion-resistant alloy plates. BACKGROUND

[0002] The processing procedure of corrosion-resistant alloy 800 series steel plates usually sequentially passes through slab heating, rolling, heat treatment quenching, shot blasting, pickling, grinding (or abrasive belt grinding), and packaging processes. Due to the material properties of the 800 series steel plates, over-pickling phenomenon easily occurs in the pickling process, so that the near-surface grain boundaries of the steel plates have transgranular phenomenon, and surface crack defects occur in the subsequent processing.

[0003] Taking N08810 corrosion-resistant alloy as an example, the alloy contains about 30% Ni, 20% Cr and other elements. It is mainly used in high-temperature corrosion-resistant environments such as oil and gas pipelines, heat exchangers, steam power turbines, etc. It is a widely used brand in corrosion-resistant alloys. During the slab heating process of the corrosion-resistant alloy plate, some iron oxide scales are generated. After the slab is dephosphorized and rolled, some iron oxide scales are still brought to the plate surface with the deformation of rolling. At the same time, the secondary iron oxide scales after rolling and the iron oxide scales during the solid solution heat treatment process are all covered on the matrix of the corrosion-resistant alloy plate (including the transition layer). In addition, some rolling defects such as pitting, folding, and scratches may occur on the surface of the corrosion-resistant alloy plate during the rolling process. According to the factory specification or technical agreement, the above defects are usually cleaned by the manufacturer. The quality state of the upper and lower surfaces of the corrosion-resistant alloy plate is determined by the processes such as shot blasting process, pickling process, and abrasive belt grinding process in the typical pressure processing process of the corrosion-resistant alloy plate. The current surface pressure processing method of the hot-rolled corrosion-resistant alloy plate mainly has the following two methods:

[0004] The first method is a process flow of slab heating, rolling, heat treatment quenching, abrasive belt grinding (or supplementary manual grinding), and packaging. The characteristic of this process flow is that the shot blasting and pickling processes in the traditional processing technology are omitted, which technically avoids the over-pickling phenomenon in the pickling process, and the subsequent user is less likely to produce crack defects, so the user's recognition degree is high. However, the disadvantage of this process is that the upper and lower surfaces of the steel plate are ground by the abrasive belt, which takes a long time, has high process cost, and has low yield.

[0005] The second process involves slab heating, rolling, heat treatment quenching, shot blasting, pickling, manual grinding (or belt grinding), and packaging. The advantages of this process are the use of shot blasting and pickling, reducing the amount of grinding or belt grinding required on the steel plate, resulting in shorter production time, lower process costs, and higher output. Pickling uses a mixed acid solution, specifically a mixture of nitric acid and hydrofluoric acid. The concentration of the mixed acid solution is 200-280 g / L for nitric acid and 20-45 g / L for hydrofluoric acid, with a temperature of 40-50℃. However, the disadvantage of this process is the risk of over-pickling the steel plate. If over-pickling occurs, the remedy is to use P40 (or P60) grit abrasive belts for coarse grinding or P80 grit abrasive belts for fine grinding or polishing.

[0006] Therefore, for 800 series corrosion-resistant alloys, there is a need for a processing method that can significantly reduce the risk of over-pickling of steel plates during the pickling process, improve the pass rate of shot blasting and pickling, shorten the production cycle, reduce process costs, and increase output per unit time. Summary of the Invention

[0007] To solve the above-mentioned technical problems, the present invention provides a surface processing method for corrosion-resistant alloy plates, comprising:

[0008] S1: Heating the slab;

[0009] S2: Roll the heated slab into a sheet;

[0010] S3: The plate material is subjected to heat treatment and water quenching;

[0011] S4: The plate after heat treatment and water quenching is shot blasted.

[0012] S5: Perform a preliminary inspection on the plate after shot blasting, preliminarily repair the defects in the plate, and check whether the number of defects on one side of the plate or the area of ​​defects on one side of the plate exceeds the threshold. If it does not exceed the threshold, proceed to the first process; if it exceeds the threshold, proceed to the second process.

[0013] Preferably, the threshold in S5 is that the number of defects that need to be ground on a single side is 80, and the area of ​​defects on a single side accounts for 5% of the total area of ​​the single side.

[0014] Preferably, the first step includes:

[0015] S51: Shot blasting is performed on the plates after the initial inspection;

[0016] S52: Pickling treatment is performed on the shot-blasted sheet material.

[0017] S53: Inspect the pickled boards, manually repair any defects, and package them after inspection.

[0018] Preferably, the second process comprises:

[0019] S61: sand belt grinding of the plate after preliminary inspection;

[0020] S62: inspection of the plate after sand belt grinding, manual grinding of the defects of the plate, and packaging after the inspection.

[0021] Preferably, the S4 and the S51 use high-carbon steel pellets, and the pellet model is S260-S280; the surface quality of the plate after the shot blasting treatment in the S4 is ASa2.5, and the surface quality of the plate after the shot blasting treatment in the S51 is between ASa2.5 and ASa3.0.

[0022] Preferably, the pickling treatment adopts mixed acid, i.e., nitric acid and hydrofluoric acid, the concentration of the mixed acid solution is 180-260 g / L of nitric acid and 15-35 g / L of hydrofluoric acid, and the temperature of the mixed acid solution is ≤45℃.

[0023] Preferably, in the S61, the sand belt grinding adopts 40# or 46# sand belt for rough grinding, and then 36# sand belt for fine grinding, and the surface roughness of the plate after the sand belt grinding is ≤6.0 μm.

[0024] Preferably, the grinding in the inspection and the preliminary inspection refers to grinding of defects such as pitting, folding, scratches, and cracks of the steel plate, and the grinding area is rectangular.

[0025] Preferably, the defect grinding adopts sand wheel grinding first, and then polishing of the grinding area by a thousand-leaf wheel.

[0026] Preferably, the surface roughness of the areas after the preliminary grinding and the manual grinding is ≤3.0 μm.

[0027] Technical effects and advantages of the present application:

[0028] On the basis of the traditional process, after the shot blasting of the plate after heat treatment quenching, the plate after the shot blasting is subjected to preliminary inspection (preliminary grinding of the defects on the plate), the defects of the plate are detected during the preliminary inspection, whether the number of single-side defects or the area of single-side defects exceeds the threshold value is determined to determine which process the plate enters, different processing methods are adopted according to the defect degree of the plate, the risk of over-pickling of the 800 series plate during pickling is greatly reduced, and the pass rate of the shot blasting and pickling of the steel plate is improved. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a surface processing method structure schematic diagram of a corrosion-resistant alloy plate provided by the embodiment of the present application;

[0030] Figure 2This is a schematic diagram of the first step in a surface processing method for a corrosion-resistant alloy plate provided in an embodiment of this application;

[0031] Figure 3 This is a schematic diagram of the second step in a surface processing method for a corrosion-resistant alloy plate provided in an embodiment of this application;

[0032] Figure 4 This is a schematic diagram illustrating a specific implementation method provided in this application.

[0033] Figure 5 This is a schematic diagram of a specific implementation method provided in this application.

[0034] In the picture:

[0035] 1. First process, 2. Second process. Detailed Implementation

[0036] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and design various embodiments with various modifications suitable for a particular purpose.

[0037] Example 1

[0038] Depend on Figures 1-3 As shown, this embodiment provides a surface processing method for a corrosion-resistant alloy plate, including:

[0039] S1: Heating the slab;

[0040] S2: Roll the heated slab into a sheet;

[0041] S3: The sheet metal undergoes heat treatment and water quenching;

[0042] S4: The plate material after heat treatment and water quenching is shot blasted.

[0043] S5: Perform initial inspection on the shot-blasted sheet, preliminarily repair defects in the sheet, and check whether the number or area of ​​defects on a single side of the sheet exceeds the threshold. If it does not exceed the threshold, proceed to the first process 1; if it exceeds the threshold, proceed to the second process 2.

[0044] The threshold value specifically refers to 80 defects on a single side, and the area of defects on a single side accounts for 5% of the total area on a single side. The first process 1 includes: S51: performing shot blasting treatment on the plate after initial inspection; S52: performing pickling treatment on the plate after shot blasting; S53: performing inspection on the plate after pickling treatment, manually grinding the defects of the plate, and packaging after completing the inspection. The second process 2 includes: S61: performing abrasive belt grinding on the plate after initial inspection, wherein the abrasive belt grinding adopts a 40# or 46# abrasive belt for rough grinding, and then a 36# abrasive belt for fine grinding, and the surface roughness Ra of the plate after abrasive belt grinding is less than or equal to 6.0 μm; S62: performing inspection on the plate after abrasive belt grinding, manually grinding the defects of the plate, and packaging after completing the inspection. In the shot blasting machine, the shot type is S260-S280, the surface quality of the plate after shot blasting in step S4 is ASa2.5, the surface quality of the plate after shot blasting in step S51 is between ASa2.5 and ASa3.0, the pickling treatment adopts mixed acid (nitric acid + hydrofluoric acid), the concentration of the mixed acid solution is 180-260 g / L of nitric acid and 15-35 g / L of hydrofluoric acid, and the temperature of the mixed acid solution is less than or equal to 45°C.

[0045] It should be noted that the grinding of the plate in the inspection and the initial inspection is manually ground by hand, which refers to grinding the defects such as pitting, folding, scratches, and cracks of the steel plate, the grinding area is rectangular, the defect grinding adopts first grinding by abrasive wheel, and then polishing the grinding area by a thousand-leaf wheel, and the surface roughness Ra of the grinding area is less than or equal to 3.0 μm. The abrasive belt grinding process is only used for individual steel plates with large-area defects on the surface of the plate during the pressure processing of the plate, and is different from the traditional process, which performs pickling after shot blasting and then performs detection and grinding after pickling. In this embodiment, if the number of defects on a single side or the area of defects on a single side does not exceed the threshold value, the plate is subjected to secondary shot blasting, and then the plate is subjected to pickling after the secondary shot blasting. The risk of over-pickling of the 800 series plate during pickling is greatly reduced, and the qualified rate of pickling is effectively improved. If the number of defects on a single side or the area of defects on a single side exceeds the threshold value, abrasive belt grinding is adopted, grinding is completed, and then inspection is performed (manual grinding is performed on the remaining defects), and packaging is performed after completing the inspection. The advantage is short production time and low process cost.

[0046] Example 2

[0047] By Figure 4As shown in the embodiment, a surface pressure tooling embodiment of N08810 corrosion-resistant alloy plate is provided (the number of single-side defects or the area of single-side defects after initial inspection does not exceed the threshold value), and the plate size is 28 mm in thickness, 2010 mm in width, and 4496 mm in length. First, the slab is heated and rolled, and the rolled plate is heat treated and quenched. After quenching, high-carbon steel pellets, model S280, are used for one-time shot blasting. Then, the plate is initially inspected (preliminary grinding), and the defects such as pitting, folding, scratching, and cracking of the steel plate are ground. The grinding area is rectangular, and the defect grinding is performed by first grinding with a grinding wheel and then polishing the grinding area with a chrysanthemum wheel. The surface roughness of the ground area of the steel plate is Ra≤3.0 μm. Next, high-carbon steel pellets, model S280, are used for two-time shot blasting, and subsequent pickling is performed using mixed acid, i.e., nitric acid + hydrofluoric acid. The mixed acid solution concentration is 220 g / L of nitric acid and 25 g / L of hydrofluoric acid, and the mixed acid solution temperature is 35°C. Then, the plate is inspected and ground, and the defects such as pitting, folding, scratching, and cracking of the steel plate are ground. The grinding area is rectangular, and the defect grinding is performed by first grinding with a grinding wheel and then polishing the grinding area with a chrysanthemum wheel. The surface roughness of the ground area of the steel plate is Ra2.5 μm. Finally, the plate is packaged (labeled), and the one-time pickling quality pass rate is stably above 99.6%.

[0048] Embodiment 3

[0049] By Figure 5 As shown in the embodiment, a surface pressure tooling embodiment of N08810 corrosion-resistant alloy plate is provided (the number of single-side defects or the area of single-side defects after initial inspection does not exceed the threshold value), and the plate size is 28 mm in thickness, 2010 mm in width, and 4496 mm in length. First, the slab is heated and rolled, and the rolled plate is heat treated and quenched. After quenching, high-carbon steel pellets, model S280, are used for one-time shot blasting. Then, the plate is initially inspected (preliminary grinding), and the defects such as pitting, folding, scratching, and cracking of the steel plate are ground. The grinding area is rectangular, and the defect grinding is performed by first grinding with a grinding wheel and then polishing the grinding area with a chrysanthemum wheel. The surface roughness of the ground area of the steel plate is Ra≤3.0 μm. Next, high-carbon steel pellets, model S280, are used for two-time shot blasting, and subsequent pickling is performed using mixed acid, i.e., nitric acid + hydrofluoric acid. The mixed acid solution concentration is 220 g / L of nitric acid and 25 g / L of hydrofluoric acid, and the mixed acid solution temperature is 35°C. Then, the plate is inspected and ground, and the defects such as pitting, folding, scratching, and cracking of the steel plate are ground. The grinding area is rectangular, and the defect grinding is performed by first grinding with a grinding wheel and then polishing the grinding area with a chrysanthemum wheel. The surface roughness of the ground area of the steel plate is Ra2.5 μm. Finally, the plate is packaged (labeled), and the one-time pickling quality pass rate is stably above 99.6%.

[0050] The working principle of the present application is:

[0051] The slab is heated, the heated slab is rolled into a plate, the plate is heat treated and quenched, the plate after heat treatment and quenching is shot blasting treated, the plate after shot blasting is preliminarily inspected (the plate defects are preliminarily polished), and whether the single-side defect quantity or single-side defect area of the plate exceeds a threshold value is detected, if not, the first process 1 is carried out, if yes, the second process 2 is carried out, the threshold value specifically refers to that the single-side defect quantity to be polished is 80, and the single-side defect area accounts for 5% of the single-side total area, the pickling treatment adopts mixed acid (nitric acid + hydrofluoric acid), the mixed acid concentration is that the nitric acid is 180-260 g / L, the hydrofluoric acid is 15-35 g / L, the mixed acid temperature is ≤45℃, the manual polishing of the plate in the inspection and preliminary inspection refers to the polishing of the defects such as the plate pitting, folding, scratch and crack, the polishing area is rectangular, the defect polishing adopts the sand wheel polishing, and the polishing area is polished by the thousand-leaf wheel, and the surface roughness Ra of the polishing area is ≤3.0 μm. The sand belt polishing process is only used for the individual plate with a large-area defect on the surface of a small amount of plates in the plate pressure processing process, and the upper and lower surfaces of the plate are polished by the sand belt, which is different from the traditional process, the traditional process is that the acid pickling is carried out after the shot blasting, the detection and polishing are carried out after the acid pickling is completed, or the upper and lower surfaces of the individual plate are polished by the sand belt, another way of the traditional process is that the plate is not shot blasted and pickled after the heat treatment and quenching, and the upper and lower surfaces of the whole batch of plates are polished by the sand belt, if the single-side defect quantity or single-side defect area does not exceed the threshold value in the embodiment, the plate is shot blasted again, the plate is pickled after the secondary shot blasting, which greatly reduces the risk of over-pickling of the 800 series plate in the pickling process, and effectively improves the qualified rate of pickling, if the single-side defect quantity or single-side defect area exceeds the threshold value, the sand belt polishing is adopted, the inspection (the remaining defects are polished) is carried out after the polishing is completed, the packaging treatment is carried out after the inspection is completed, and the advantages are short production time and low process cost.

[0052] Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art and related fields without creative labor should belong to the protection scope of the present application. The structures, devices and operation methods not specifically described and explained in the present application are implemented according to the conventional means in the art, if not specially described and limited.

Claims

1. A surface processing method for a corrosion-resistant alloy plate, characterized in that, include: S1: Heating the slab; S2: Roll the heated slab into a sheet; S3: The plate material is subjected to heat treatment and water quenching; S4: The plate after heat treatment and water quenching is shot blasted. S5: Perform a preliminary inspection on the plate after shot blasting, perform preliminary grinding on the plate defects, and check whether the number of defects on one side of the plate or the area of ​​defects on one side exceeds the threshold. If it does not exceed the threshold, proceed to the first process (1); if it exceeds the threshold, proceed to the second process (2). The threshold in S5 is specifically defined as follows: the number of single-sided grinding defects is ≥80, or the area of ​​single-sided grinding defects accounts for ≥5% of the total area of ​​a single side. The first process (1) includes: S51: Shot blasting is performed on the plates after the initial inspection; S52: Pickling treatment is performed on the shot-blasted sheet material. S53: Inspect the pickled boards, manually repair any defects, and package them after inspection. The second process (2) includes: S61: Sanding the boards after initial inspection; S62: Inspect the plates after sanding with a sanding belt, manually repair any defects in the plates, and then package them after inspection.

2. The surface processing method for a corrosion-resistant alloy plate according to claim 1, characterized in that, In S4 and S51, the shot blasting machine uses high-carbon steel shot, with shot type S260-S280. The surface quality of the plate after shot blasting in S4 is ASa2.5, and the surface quality of the plate after shot blasting in S51 is between ASa2.5 and ASa3.

0.

3. The surface processing method for a corrosion-resistant alloy plate according to claim 1, characterized in that, The pickling treatment uses a mixed acid solution, specifically a mixture of nitric acid and hydrofluoric acid. The concentration of the mixed acid solution is 180-260 g / L for nitric acid and 15-35 g / L for hydrofluoric acid. The temperature of the mixed acid solution is ≤45℃.

4. The surface processing method for a corrosion-resistant alloy plate according to claim 1, characterized in that, In step S61, the belt grinding process uses a 40# or 46# abrasive belt for coarse grinding, followed by a 36# abrasive belt for fine grinding. After belt grinding, the surface roughness Ra of the board is ≤6.0μm.

5. The surface processing method for a corrosion-resistant alloy plate according to claim 1, characterized in that, The aforementioned inspection and the initial inspection refer to the grinding of the steel plate to repair defects such as pitting, folds, scratches, and cracks.

6. The surface processing method for a corrosion-resistant alloy plate according to claim 5, characterized in that, Preliminary grinding of sheet metal defects and manual grinding of sheet metal defects refer to the grinding of defects such as pitting, folding, scratches, and cracks in steel plates. The grinding area is rectangular. The defect grinding is carried out by first grinding with a grinding wheel and then polishing the grinding area with a flap wheel.

7. The surface processing method for a corrosion-resistant alloy plate according to claim 6, characterized in that, The surface roughness Ra of the grinding area is ≤3.0μm.

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