Method for solving problems of hole flanging and cracking of stainless steel thick plate floor drain product

Abstract

The invention provides a method for solving the problem of hole flanging and cracking of a stainless steel thick plate floor drain product, the stainless steel thick plate floor drain contains 0.2%-0.3% of Cu, the thickness of the stainless steel thick plate floor drain is 2.5-3.5 mm, the difference of the same plate is smaller than or equal to 0.02 mm, the tensile strength is 710-730 Mpa, the yield strength is 260-280 Mpa, the ductility is larger than or equal to 60%, and the hardness is smaller than or equal to HRB 82. The method has the beneficial effects that the production mechanism and influence factors of the austenitic stainless steel stamping hole flanging defect can be analyzed in detail, standardized process parameter control is formulated according to the production process characteristics of the whole process of the product, component selection and Md30 and grain size index control are innovatively and initially increased, the cracking problem is effectively solved, and the production efficiency is improved. The product quality is improved, and a certain economic effect is created.

Description

Technical Field

[0001] The invention belongs to the technical field of stainless steel, and in particular relates to a solution to the problem of hole flipping and cracking of stainless steel thick plate floor drain products. Background Art

[0002] 0Cr18Ni9DQ austenitic stainless steel is widely used in the bathroom decoration industry due to its good corrosion resistance, low magnetism and formability. With the development of society and the needs of the industry, the market supply of products is gradually increasing. However, during the processing and use of bathroom floor drain products, 3.0mm thick 0Cr18Ni9DQ stainless steel thick plates will have hole-turning cracking defects, with a cracking ratio of 20%-30%. To solve this problem, market customers need to increase the coating and improve the mold accuracy to adjust, which seriously reduces work efficiency and increases process costs. Therefore, solving the hole-turning cracking problem of austenitic stainless steel thick plates has become a key technical research direction.

[0003] After consulting the existing published patent documents, CN202715712U and CN113523056A both disclose that the problem of cracking of finished products is solved by improving the hole-turning die. There is an essential difference between the above documents and the method field of solving the problem involved in the patent of the present invention. Summary of the invention

[0004] In view of this, the present invention aims to propose a solution to the problem of hole flipping and cracking of stainless steel thick plate floor drain products, so as to solve the problems existing in the background technology.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows: A solution to the problem of cracking of stainless steel thick plate floor drain products. The stainless steel thick plate floor drain contains 0.2%-0.3% Cu, and the thickness of the stainless steel thick plate floor drain is 2.5-3.5mm, the difference between the same plate is ≤0.02mm, the tensile strength is 710-730Mpa, the yield strength is 260-280Mpa, the elongation is ≥60%, and the hardness is ≤HRB 82.

[0006] Furthermore, the stainless steel thick plate floor drain includes, by weight percentage: C: 0.03%-0.05%, Si: ≤0.75%, Mn: 1.0%-1.2%, Ni: 8%-8.2%, Cr: 18%-18.5%, N: 0.04%-0.06%, Cu: 0.2%-0.3% and other impurity elements: P: ≤0.04%, S: ≤0.03%.

[0007] Preferably, the thickness of the stainless steel thick plate floor drain is 3 mm.

[0008] Furthermore, the sum of the weight percentages of C and N in the stainless steel thick plate floor drain is ≤0.09%.

[0009] Furthermore, the value of Md30 is 5-10°C and the thickness of the stainless steel thick plate floor drain is 2.5-3.5mm Furthermore, the calculation formula according to the elemental composition is as follows: Md30=551-462*(WC+WN)-9.2*WSi-8.1*WMn-13.7*WCr-29*(WNi+WCu)-18.5*WMo; WC is the weight percentage of C; WN is the weight percentage of N; WSi is the weight percentage of Si; WMn is the weight percentage of Mn; WCr is the weight percentage of Mn; WNi is the weight percentage of Ni; WCu is the weight percentage of Cu; WMo is the weight percent of Mo.

[0010] Furthermore, the preparation method of the stainless steel thick plate floor drain includes the steps of hot rolled coil annealing and pickling, rolling, cold rolled coil annealing and pickling, and flattening to obtain a stainless steel product for punching and punching.

[0011] The raw materials are annealed and pickled by hot-rolled coils. The hot-rolled black steel coils with a thickness of 5.0 mm are annealed and pickled to obtain NO.1 plates with a clean surface and silvery white color. The NO.1 plates are rolled according to a deformation amount of 40% to obtain cold-rolled hard coils with a thickness of 3.0 mm. The cold-rolled hard coils are annealed and pickled. The plate temperature in the heating section of the furnace is controlled at 1170-1180°C. The cooling mode of air cooling and water cooling is adopted. The plate temperature in the cooling section is controlled at 200-240°C. Then, the stainless steel surface is treated to remove the oxide scale and form a passivation layer through electrolytic sodium sulfate, electrolytic nitric acid, and mixed acid sections. After the stainless steel surface is treated to remove the oxide scale and form a passivation layer, it is tempered and leveled according to a deformation amount of 0.4%.

[0012] Compared with the prior art, the solution to the problem of cracking of stainless steel thick plate floor drain products described in the present invention has the following advantages: This application can analyze in detail the generation mechanism and influencing factors of punching and hole-flashing defects in austenitic stainless steel, and formulate standardized process parameter control based on the production process characteristics of the entire product process, innovatively and for the first time increase component selection, Md30 and grain size index control, effectively solve the cracking problem, achieve product quality improvement, and create certain economic results.

[0013] The process parameters involved in this solution were originally designed to only consider the basic physical performance parameters and surface quality requirements of stainless steel products, and belong to the common parameter range in the industry for the production process of austenitic stainless steel. According to the quality control concept of conventional products, if there is no idea and quality requirement for grain size index control, the process parameters of each process of cold rolling production will not be changed. Therefore, for the concept of grain size index control innovatively proposed in this solution, it is necessary to break the conventional process parameter range and redefine the parameter range to follow up the roughness index control of each process. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0015] Figure 1 This is a schematic diagram of the use of the stainless steel thick plate floor drain described in Example 1 of the present invention; Figure 2 This is a schematic diagram of the use of the stainless steel thick plate floor drain described in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0016] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0017] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0018] Example: The cold rolling mill produces stainless steel finished coils, and the raw materials are all hot-rolled black steel coils. The raw material composition WC+WN=0.085%, Md30=9.5℃ are selected. First, in the raw material annealing and pickling unit, the hot-rolled black steel coil with a thickness of 5.0mm is annealed and pickled to obtain the NO.1 plate with a clean surface and silvery white color.

[0019] The NO.1 plate was rolled with a deformation amount of 40% to obtain a cold-rolled hard coil with a thickness of 3.0 mm.

[0020] The cold-rolled hard coils are annealed and pickled. The plate temperature in the heating section of the furnace is controlled at 1170-1180°C, and the cooling mode of air cooling + water cooling is adopted. The plate temperature in the cooling section is controlled at 200-240°C. Then, the stainless steel surface is treated to remove the oxide scale and form a passivation layer through the electrolytic sodium sulfate, electrolytic nitric acid and mixed acid sections.

[0021] According to the deformation amount of 0.4%, the steel coil with mechanical properties of tensile strength 716MPa, yield strength 268MPa, hardness HRB 81.5, and elongation 60.5% was obtained. The metallographic structure grain size grade is 7. The product produced according to the process of the embodiment is applied to the floor drain product, and the stamping cracking rate is 1.8%, and the application is as follows Figure 1 shown.

[0022] Comparative Example 1: The raw material composition C+N=0.095%, Md30=11.3℃ was selected. First, in the raw material annealing and pickling unit, the hot-rolled black steel coil with a thickness of 5.0mm was annealed and pickled to obtain the NO.1 plate with a clean surface and silvery white color.

[0023] The NO.1 plate is rolled with a deformation of 40% to obtain a cold-rolled hard coil with a thickness of 3.0 mm. The cold-rolled hard coil is annealed and pickled. The plate temperature in the heating section of the furnace is controlled at 1170-1180°C, and the cooling mode of air cooling + water cooling is adopted. The plate temperature in the cooling section is controlled at 200-240°C. Then, the stainless steel surface is treated to remove the oxide scale and form a passivation layer through the electrolytic sodium sulfate, electrolytic nitric acid and mixed acid sections.

[0024] According to the deformation of 0.4%, the steel coil with mechanical properties of tensile strength of 746MPa, yield strength of 296MPa, hardness HRB 83.2 and elongation of 59.1% was obtained. The metallographic structure grain size grade is 7, and the product produced according to the process of the embodiment is applied to the floor drain product, and the stamping cracking rate is 12.5%. Figure 2 shown.

[0025] Comparative Example 2: The raw material composition C+N=0.082%, Md30=15.6℃ was selected. First, in the raw material annealing and pickling unit, the hot-rolled black steel coil with a thickness of 5.0mm was annealed and pickled to obtain the NO.1 plate with a clean surface and silvery white color.

[0026] The NO.1 plate is rolled with a deformation of 40% to obtain a cold-rolled hard coil with a thickness of 3.0mm. The cold-rolled hard coil is annealed and pickled. The plate temperature in the heating section of the furnace is controlled at 1170-1180℃, and the cooling mode of air cooling + water cooling is adopted. The plate temperature in the cooling section is controlled at 200-240℃. Then, the stainless steel surface is treated to remove the oxide scale and form a passivation layer through the electrolytic sodium sulfate, electrolytic nitric acid and mixed acid sections.

[0027] According to the deformation amount of 0.4%, the steel coil was tempered and leveled to obtain the mechanical properties of tensile strength 720MPa, yield strength 278MPa, hardness HRB 82.3, elongation 59.8%. The metallographic structure grain size grade is 7. The product produced according to the process of the embodiment is applied to floor drain products, and the stamping cracking rate is 15%.

[0028] Comparative Example 3: The raw material composition C+N=0.085%, Md30=9.5℃ were selected. First, in the raw material annealing and pickling unit, the hot-rolled black steel coil with a thickness of 5.0mm was annealed and pickled to obtain the NO.1 plate with a clean surface and silvery white. The NO.1 plate was rolled at a deformation of 50% to obtain a cold-rolled hard coil with a thickness of 3.0mm.

[0029] The cold-rolled hard coils are annealed and pickled. The plate temperature in the heating section of the furnace is controlled at 1170-1180°C, and the cooling mode of air cooling + water cooling is adopted. The plate temperature in the cooling section is controlled at 200-240°C. Then, after electrolysis of sodium sulfate, electrolysis of nitric acid, and mixed acid sections, the surface of the stainless steel is treated to remove the oxide scale and form a passivation layer. According to the deformation amount of 0.4%, the steel coils with mechanical properties such as tensile strength of 732MPa, yield strength of 287MPa, hardness HRB 82.8, and elongation of 59.6% are obtained. The metallographic structure has a grain size grade of 7. The products produced according to the embodiment process are applied to floor drain products, and the stamping cracking rate is 8.6%.

[0030] Comparative Example 4: The raw material composition C+N=0.085%, Md30=9.5℃ were selected. First, in the raw material annealing and pickling unit, the hot-rolled black steel coil with a thickness of 5.0mm was annealed and pickled to obtain the NO.1 plate with a clean surface and silvery white color. The NO.1 plate was rolled according to a deformation amount of 40% to obtain a cold-rolled hard coil with a thickness of 3.0mm.

[0031] Annealing and pickling are carried out for the cold-rolled hard coils. The plate temperature in the heating section of the furnace is controlled at 1150-1160℃, and the cooling mode of air cooling + water cooling is adopted. The plate temperature in the cooling section is controlled at 260-280℃. Then, the stainless steel surface is treated to remove the oxide scale and form a passivation layer through the electrolytic sodium sulfate, electrolytic nitric acid and mixed acid sections.

[0032] According to the 0.4% deformation, the steel coil was tempered and leveled to obtain the mechanical properties of tensile strength 745MPa, yield strength 302MPa, hardness HRB 83.6, elongation 57.5%. The metallographic structure grain size grade is 7.5.

[0033] The product produced according to the process of the embodiment is applied to floor drain products, and the stamping cracking rate is 10.5% The technical innovation of this solution lies in the ability to analyze in detail the generation mechanism and influencing factors of punching and hole-flashing defects in austenitic stainless steel, and to formulate standardized process parameter control based on the production process characteristics of the entire product process, innovatively and for the first time increase component selection, Md30 and grain size index control, effectively solve the cracking problem, achieve product quality improvement, and create certain economic results.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A solution to the problem of cracking of stainless steel thick plate floor drain products, characterized by: The stainless steel thick plate floor drain contains 0.2%-0.3% Cu, and the thickness of the stainless steel thick plate floor drain is 2.5-3.5mm, the difference between the same plate is ≤0.02mm, the tensile strength is 710-730Mpa, the yield strength is 260-280Mpa, the elongation is ≥60%, and the hardness is ≤HRB 82.

2. The method for solving the problem of cracking of stainless steel thick plate floor drain according to claim 1 is characterized by: Stainless steel thick plate floor drain, including by weight percentage: C: 0.03%-0.05%, Si: ≤0.75%, Mn: 1.0%-1.2%, Ni: 8%-8.2%, Cr: 18%-18.5%, N: 0.04%-0.06%, Cu: 0.2%-0.3% and other impurity elements: P: ≤0.04%, S: ≤0.03%.

3. The solution to the problem of cracking of stainless steel thick plate floor drain products according to claim 1 is characterized by: The sum of the weight percentages of C and N in stainless steel thick plate floor drains is ≤0.09%.

4. The solution to the problem of cracking of stainless steel thick plate floor drain products according to claim 1 is characterized by: The value of Md30 is 5-10℃.

5. The solution to the problem of cracking of stainless steel thick plate floor drain products according to claim 4 is characterized by: The calculation formula based on element composition is as follows: Md30=551-462*(WC+WN)-9.2*WSi-8.1*WMn-13.7*WCr-29*(WNi+WCu)-18.5*WMo; WC is the weight percentage of C; WN is the weight percentage of N; WSi is the weight percentage of Si; WMn is the weight percentage of Mn; WCr is the weight percentage of Mn; WNi is the weight percentage of Ni; WCu is the weight percentage of Cu; WMo is the weight percent of Mo.

6. The solution to the problem of cracking of stainless steel thick plate floor drain products according to claim 1 is characterized by: The preparation method of the stainless steel thick plate floor drain comprises the following steps: the raw materials are subjected to hot-rolled coil annealing and pickling, rolling, cold-rolled coil annealing and pickling, and flattening production and processing to obtain a stainless steel product for punching and hole turning.

7. The solution to the problem of cracking of stainless steel thick plate floor drain products according to claim 6 is characterized by: The raw materials are annealed and pickled by hot-rolled coils. The hot-rolled black steel coils with a thickness of 5.0 mm are annealed and pickled to obtain NO.1 plates with a clean surface and a silvery white color.

8. The solution to the problem of cracking of stainless steel thick plate floor drain products according to claim 7 is characterized by: The NO.1 plate was rolled with a deformation amount of 40% to obtain a cold-rolled hard coil with a thickness of 3.0 mm.

9. The solution to the problem of cracking of stainless steel thick plate floor drain products according to claim 8 is characterized by: The cold-rolled hard coils are annealed and pickled. The plate temperature in the heating section of the furnace is controlled at 1170-1180℃. Air cooling and water cooling are adopted. The plate temperature in the cooling section is controlled at 200-240℃. Then, the stainless steel surface is treated with electrolytic sodium sulfate, electrolytic nitric acid and mixed acid to remove the oxide scale and form a passivation layer.

10. A solution to the problem of cracking of stainless steel thick plate floor drain products according to claim 9, characterized in that: After removing the oxide scale and forming a passivation layer on the stainless steel surface, it is tempered and leveled with a deformation amount of 0.4%.

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