A method for predicting water ripples in bevel grinding

Abstract

The present invention provides a method for predicting water ripples in bevel grinding. The method comprises the following steps: cutting raw steel at the center position of its plate width along the length direction of the raw steel and performing acid corrosion treatment on the raw steel; dividing the cross section into three equal parts along the thickness direction of the raw steel to form a middle region and two side edge regions; measuring the primary carbide diameter in each region, measuring the width distance between the primary carbide in each region and the thickness edge of the raw steel closest to the primary carbide in each region, and measuring the thickness of the raw steel; and calculating the ratio of the width distance to the thickness of the raw steel; if ① the primary carbide diameter in the middle region is ≥5μm and the position of at least one primary carbide in the middle region satisfies the following: a / w<0.4, or ② the primary carbide diameter in the two side edge regions is ≥3μm and the position of at least one primary carbide in the two side edge regions satisfies the following: a / w<0.4, the method is rated as "B" and is prone to generating water ripples in bevel grinding; if the above ① and ② are not satisfied, the method is rated as "A" and is not prone to generating water ripples in bevel grinding.

Description

Technical Field

[0001] The invention belongs to the field of stainless steel metallographic inspection, in particular to a method for predicting water ripples in bevel grinding. Background Art

[0002] Knife stainless steel typically contains 13% or more chromium (e.g., 30Cr13: 0.3% carbon, 13% chromium; 40Cr13: 0.4% carbon, 13% chromium, etc.). Knife stainless steel grades with a carbon content of 0.3% or more commonly exhibit moiré due to carbon segregation, affecting the product's aesthetics and potentially leading to product degradation and scrapping.

[0003] Currently, there are no reports, either domestically or internationally, on technologies for predicting water ripples in bevel grinding. While conventional metallographic examination can detect carbon segregation, it cannot truly reflect the probability of water ripples occurring in bevel grinding. Therefore, a method for predicting water ripples in bevel grinding is urgently needed to reduce user losses and provide guidance on product selection. Summary of the Invention

[0004] The object of the present invention is to provide a method for predicting water ripples during bevel grinding.

[0005] The technical solution for achieving the purpose of the present invention is: a method for predicting water ripples in bevel grinding, comprising the following steps:

[0006] (1) Carbon segregation corrosion treatment: The raw steel for bevel grinding is cut along the length direction of the raw steel at the center of the plate width, and the resulting cross section is subjected to acid corrosion treatment;

[0007] (2) Observe and measure the primary carbides on the metallographic image of the cross section obtained in step (1): divide the cross section into three equal parts along the thickness direction of the raw steel to form a middle region and two side regions, and observe the distribution of the primary carbides in the two side regions and the primary carbides in the middle region respectively; measure the diameter of the primary carbides in each region; measure the width distance between the primary carbide in each region and the thickness edge of the raw steel closest to it and the thickness of the raw steel, and calculate the ratio of the width distance to the thickness of the raw steel;

[0008] (3) Rating criteria:

[0009] ① The diameter of the primary carbide in the middle region is ≥5μm, and the position of at least one primary carbide in the middle region satisfies the following conditions: a / w < 0.4;

[0010] ② The diameter of the primary carbide in the edge regions on both sides is ≥ 3 μm, and the position of at least one primary carbide in the edge regions on both sides satisfies: a / w < 0.4;

[0011] If the above ① or ② are met, it is rated as "B" and is prone to produce water ripples when sharpening the knife;

[0012] If the above ① and ② are not met, it is rated as "A" and is not prone to water ripples caused by oblique grinding.

[0013] During long-term testing, the inventors discovered that when carbon segregation is severe and located close to the edge, water ripple defects will appear during the bevel grinding process. Based on this, the present invention provides a method for predicting water ripples in bevel grinding. Raw steel rated "B" is prone to water ripples in bevel grinding and is not suitable for bevel grinding production. Raw steel rated "A" is less likely to produce water ripples in bevel grinding and can be used for bevel grinding. This method can predict the suitability of raw steel for bevel grinding production, provide guidance and determine the use of raw steel, and reduce user losses.

[0014] Preferably, the acid etching solution in step (1) is a hydrochloric acid / ferric chloride solution prepared by mixing 4-5 g of ferric chloride, 40-50 ml of hydrochloric acid, and 200-250 ml of water, and the etching time is 5-10 seconds. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the position measurement of primary carbides on the cross section of raw steel according to the present invention, wherein the dotted line is the bisection line dividing the cross section of the raw steel into three equal parts;

[0016] Figures 2 to 14 1 and 2 are metallographic images of the cross sections of the raw steels of Samples 1 to 13 of the present invention. Implementation Method

[0017] The following examples are provided to further illustrate the present invention, but are not intended to limit the present invention. The technical solutions described in the present invention, unless otherwise specified, are conventional solutions in the art; the reagents and materials described, unless otherwise specified, are all from commercial sources.

[0018] A method for predicting water ripples during bevel grinding comprises the following steps:

[0019] (1) Carbon segregation corrosion treatment: The raw steel 10 (martensitic stainless steel containing 13% or more of chromium) for bevel grinding is cut along the length direction of the raw steel 10 at the center of the plate width, and the formed cross section 100 is subjected to acid corrosion treatment so that the first carbide 200 is displayed on the metallographic diagram of the cross section 100; wherein the corrosion solution of the acid corrosion is:

[0020] Prepare a hydrochloric acid / ferric chloride solution made from 4-5g of ferric chloride, 40-50ml of hydrochloric acid, and 200-250ml of water. The etching time is 5-10s.

[0021] (2) Observe and measure the primary carbide 200 on the metallographic image of the cross section 100 obtained in step (1): Divide the cross section 100 into three equal parts along the thickness direction of the raw steel 10 to form a middle area and two side areas, and observe the two side areas respectively.

[0022] The distribution of primary carbides 200 in the central region and the primary carbides 200 in the middle region is measured; the diameter D of the primary carbides 200 in each region is measured; the width distance between the primary carbides 200 in each region and the thickness edge 101 of the raw material steel closest to the primary carbide 200 is measured;

[0023] The distance a and the thickness w of the raw steel 10 are calculated, and the ratio a / w of a to w is calculated;

[0024] (3) Rating criteria:

[0025] ① The diameter of the primary carbide in the middle region is ≥5μm, and the position of at least one primary carbide in the middle region satisfies the following conditions: a / w < 0.4;

[0026] ② The diameter of the primary carbide in the edge regions on both sides is ≥ 3 μm, and the position of at least one primary carbide in the edge regions on both sides satisfies: a / w < 0.4;

[0027] If the above ① or ② are met, it is rated as "B" and is prone to produce water ripples when sharpening the knife;

[0028] If the above ① and ② are not met, it is rated as "A" and is not prone to water ripples caused by oblique grinding.

[0029] Thirteen stainless steel samples (i.e., samples 1 to 13) selected from different batches were tested according to the method for predicting water ripples during bevel grinding. Cross-sectional metallographic photographs were observed, measured, and calculated. The results are as follows:

[0030] Table 1

[0031]

[0032] Table 2

[0033]

[0034] From Table 1 and Table 2 above, we can see that samples 1, 2, 6 to 8, 10 and 11 are all “A” grade products (metallographic images as shown in Figure 2 、 3 , 7~9, 11, 12), can be used to make oblique grinding knives; samples 3~5, 9, 12 and 13 are all "B" grade products (metallographic diagram as shown Figures 4-6 、 Figure 10 、 Figure 13 、 Figure 14are not suitable for making bevel sharpening knives.

[0035] The acid etching step of the present invention is not limited to: a hydrochloric acid / ferric chloride solution prepared by mixing 4-5 g of ferric chloride, 40-50 ml of hydrochloric acid, and 200-250 ml of water, with an etching time of 5-10 seconds; the acid etching step may also use a nitric acid ethanol solution specified in the industry standard "Central Carbon Segregation Evaluation Standard" or a stainless steel acid etching solution such as a 65% hydrochloric acid aqueous solution used in the prior art, as long as the primary carbides on the cross section of the raw steel can be revealed.

[0036] For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A method for predicting water ripples during bevel grinding, characterized in that: The following steps are involved: (1) Carbon segregation corrosion treatment: The raw steel for bevel grinding is cut along the length direction of the raw steel at the center of the plate width, and the resulting cross section is subjected to acid corrosion treatment; (2) Observe and measure the primary carbides on the metallographic image of the cross section obtained in step (1): divide the cross section into three equal parts along the thickness direction of the raw steel to form a middle region and two side regions, and observe the distribution of the primary carbides in the two side regions and the primary carbides in the middle region respectively; measure the diameter of the primary carbides in each region; measure the width distance a between the primary carbide in each region and the thickness edge of the raw steel closest to it and the thickness w of the raw steel, and calculate the ratio a / w of the width distance to the thickness of the raw steel; (3) Rating criteria: ① The diameter of the primary carbide in the middle region is ≥5μm, and the position of at least one primary carbide in the middle region satisfies the following conditions: a / w < 0.4; ② The diameter of the primary carbide in the edge regions on both sides is ≥ 3 μm, and the position of at least one primary carbide in the edge regions on both sides satisfies: a / w < 0.4; If the above ① or ② are met, it is rated as "B" and is prone to produce water ripples when sharpening the knife; If the above ① and ② are not met, it is rated as "A" and is not prone to water ripples caused by oblique grinding.

2. The method for predicting water ripples during bevel grinding according to claim 1, characterized in that: The acid etching solution in step (1) is a hydrochloric acid / ferric chloride solution prepared by mixing 4-5 g of ferric chloride, 40-50 ml of hydrochloric acid, and 200-250 ml of water. The etching time is 5-10 seconds.

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