HIGH-STRENGTH DOUBLE-SIDED STAINLESS STEEL COMPOSITE BOARD AND MANUFACTURING METHOD THEREFOR

Abstract

Disclosed in the present invention is a high-strength double-sided stainless steel clad sheet, including a substrate layer, and stainless steel clad layers clad-rolled on double sides of the substrate layer. The substrate layer consists, in mass percent, the chemical elements: C: 0.03-0.12%, 0<Si0.30%, Mn: 0.2-1.0%, Al: 0.02-0.04%, Ti: 0.01-0.03%, Nb: 0.005-0.020%, d N: 0.003-0.006%, with the balance being iron and other inevitable impurities. Also disclosed in the present invention is a manufacturing method for the high-strength double-sided stainless steel clad sheet, including the steps of: (1) obtaining the substrate layer and the stainless steel clad layer; (2) billet making; (3) clad-rolling; and (4) solution annealing and pickling treatment: controlling the solution temperature to be 950-1020 C., and then cooling down to room temperature at an average cooling rate of 20-50 C./s.

Claims

1. A high-strength double-sided stainless steel clad sheet, comprising a substrate layer and stainless steel clad layers clad-rolled on opposing sides of the substrate layer, wherein the substrate layer consists o, in mass percent, chemical elements: C: 0.03-0.12%, 0Si0.30%, Mn: 0.2-1.0%, Al: 0.02-0.04%, Ti: 0.01-0.03%, Nb: 0.005-0.020%, and N: 0.003-0.006%, with the balance being iron and other inevitable impurities.

2. The high-strength double-sided stainless steel clad sheet of claim I, wherein the chemical elements in the substrate layer also satisfy: 2.7C+0.4Si+Mn1.25, wherein C, Si and Mn each represent mass percent respectively,

3. The high-strength double-sided stainless steel clad sheet of claim 1, wherein a microstructure of the substrate layer is ferrite+pearlite+bainite, or ferrite+pearlite+bainite+widmanstatten, wherein a phase proportion of the bainite is 20%, and a phase proportion of the widmanstatten is 10%.

4. The high-strength double-sided stainless steel clad sheet of claim 1, wherein the ferrite in the microstructure of the substrate layer has a grain size numbergrade 7.

5. The high-strength double-sided stainless steel clad sheet of claim 1, wherein the clad sheet has a yield strength at room temperature of 300 MPa to 420 MPa, an elongation rate at room temperature of 30% to 48%, and a value of yield platform during mechanical stretching of 2.0%.

6. The high-strength double-sided stainless steel clad sheet of claim 1, wherein the stainless steel clad layer is an austenitic stainless steel clad layer.

7. The high-strength double-sided stainless steel clad sheet of claim 6, wherein austenitic stainless steel is CrNi based stainless steel or CrNiMo based stainless steel.

8. The high-strength double-sided stainless steel clad sheet of claim 1, wherein a total thickness of the double-sided stainless steel clad layer accounts for 10%-30% of a full thickness of the high-strength double-sided stainless steel clad sheet, and the stainless steel clad layer on upper and lower surfaces of the substrate layer is set to be symmetrical or asymmetrical in thickness.

9. A manufacturing method for the high-strength double-sided. stainless steel clad sheet of claim 1, comprising the steps of: (a) obtaining a substrate layer and a stainless steel clad layer; (b) billet making; (c) clad-rolling; and (d) solution annealing and pickling treatment: controlling the solution temperature to be 950-1020 C., and then cooling down to room temperature at an average cooling rate of 20-50 C./s.

10. The manufacturing method of claim 9, wherein the average cooling rate in the step (d) is 20-35 C./s.

11. The manufacturing method of claim 9, further comprising the steps of: (e) cold rolling; and (f) solution annealing, pickling and leveling treatment: controlling the solution temperature to be from 950-1020 C., and then cooling down to room temperature at an average cooling rate of 20-50 C./s.

12. The manufacturing method of claim 11, wherein the solution temperature in the-step (f) is from 950-1000 C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] FIG. 1 schematically shows the microstructure of a substrate layer of a high-strength double-sided stainless steel clad sheet of Example 4 of the present invention;

[0046] FIG. 2 schematically shows the microstructure of a stainless steel clad layer of the high-strength double-sided stainless steel clad sheet of Example 4 of the present invention, and there is no carbide precipitation;

[0047] FIG. 3 schematically shows the microstructure around a bonding interface of the high-strength double-sided stainless steel clad sheet of Example 4 of the present invention.

DETAILED DESCRIPTION

[0048] The following will further explain and describe the high-strength double-sided stainless steel clad sheet and a manufacturing method therefor of the present invention with reference to the drawings attic description and specific embodiments, but the explanation and description do not improperly limit the technical solution of the present invention. Examples 1-8 and Comparative Example 1.

[0049] Table 1-1 and Table 1-2 list the mass percent of each chemical element in substrate layers of high-strength double-sided stainless steel clad sheets and models of stainless steel clad layers of Examples 1-8 and Comparative Example 1.

[0050] It should be noted that the stainless steel clad layers of the high-strength double-sided stainless steel clad sheets of Examples 1-8 and Comparative Example 1 are all stainless steels that are available in the prior art. Therefore, Tables 1-1 and 1-2 only list the specific models of the stainless steel clad layers, and the composition of various chemical elements will not be recorded.

TABLE-US-00001 TABLE 1-1 (wt %, the balance being Fe and other inevitable impurities excluding S and P) C Si Mn P S Ti Nb Al N Example substrate 0.030 0.30 0.78 0.020 0.015 0.025 0.008 0.03 0.004 1 layer stainless Model: 304, CrNi based austenitic stainless steel clad layer steel clad layer Example substrate 0.070 0.23 0.82 0.011 0.002 0.016 0.010 0.02 0.003 2 layer stainless Model: 304L, CrNi based austenitic stainless steel clad layer steel clad layer Example substrate 0.040 0.02 0.32 0.014 0.008 0.030 0.005 0.04 0.006 3 layer stainless Model: 304, CrNi based austenitic stainless steel clad layer steel clad layer Example substrate 0.042 0.02 0.36 0.011 0.008 0.030 0.005 0.03 0.004 4 layer stainless Model: 304L, CrNi based austenitic stainless steel clad layer steel clad layer Example substrate 0.100 0.18 0.82 0.013 0.003 0.010 0.020 0.03 0.004 5 layer stainless Model: 304L, CrNi based austenitic stainless steel clad layer steel clad layer Example substrate 0.044 0.05 0.20 0.013 0.002 0.012 0.007 0.04 0.005 6 layer stainless Model: 304, CrNi based austenitic stainless steel clad layer steel clad layer Example substrate 0.120 0.21 0.84 0.010 0.005 0.015 0.015 0.03 0.005 7 layer stainless Model: 316L, CrNiMo based austenitic stainless steel clad layer steel clad layer Example substrate 0.062 0.17 1.00 0.010 0.001 0.018 0.008 0.03 0.004 8 layer stainless Model: 316L, CrNiMo based austenitic stainless steel clad layer steel clad layer Comparative substrate 0.003 0.02 0.15 0.010 0.007 0.050 0.006 0.04 0.004 Example 1 layer stemless Model: 304L, CrNi based austenitic stainless steel clad layer steel clad layer

TABLE-US-00002 TABLE 1-2 (wt %, the balance being Fe and other inevitable impurities excluding S and P) Percent of total thickness of double-sided stainless steel clad layers in full Thickness thickness of (stainless steel high-strength Microstructure Ferrite clad layer-substrate double-sided 2.7 C + 0, and phase grain size layer-stainless stainless steel 4 Si + Mn proportion number steel clad layer, mm) clad sheet (%) Example substrate layer 0.98 F + P + 10% B Grade 8 0.3-2.4-0.3 20 1 stainless steel clad layer / Example substrate layer 1.10 F + P + 15% B Grade 8 0.15-1.2-0.15 20 2 stainless steel clad layer / Example substrate layer 0.44 F + P + 10% B Grade 8.5 0.1-0.8-0.1 20 3 stainless steel clad layer / Example substrate layer 0.48 F + P + 5% B Grade 7 0.3-2.4-0.3 20 4 stainless steel clad layer / Example substrate layer 1.16 F + P + 15% B + 5% W Grade 7 0.4-3.2-0.4 20 5 stainless steel clad layer / Example substrate layer 0.34 F + P + 3% B Grade 8.5 0.1-1.8-0.1 10 6 stainless steel clad layer / Example substrate layer 1.25 F + P + 20% B + 10% W Grade 7 0.45-2.1-0.45 30 7 stainless steel clad layer / Example substrate layer 1.24 F + P + 15% B Grade 7.5 0.12-0.96-0.12 20 8 stainless steel clad layer / Comparative substrate layer 0.17 F Grade 7.5 Example 1 stainless steel clad layer / 0.15-0.7-0.15 30

[0051] Note: C, Si and Mn in the formula of 2.7C+0.4Si+Mn each represent respective mass percent of the element, and the value which is substituted into the above formula should the value before the percent sign (%), for example, when the mass percent of C is 0.1%, the mass percent of Si is 0.2%, and the mass percent of Mn is 0.7%, the values which are substituted into the formula are 0.1, 0.2, and 0.7 respectively, and the calculated value is 2.7C+0.4Si+Mn=2.70.1+0.40.2+0.7=1.05.

[0052] It should be noted that in Table 1-2, F represents ferrite, P represents pearlite, B represents bainite, and W represents widmanstatten structure.

[0053] The high-strength double-sided stainless steel clad sheets of Examples 1-8 and Comparative Example 1 are prepared by the following steps (the specific process parameters are listed in Table 2):

[0054] (1) According to Table 1-1 and Table 1-2, the substrate layer and the stainless steel clad layer are obtained, wherein austenitic stainless steel is subjected to steelmaking, continuous casting, rolling, solution annealing, precision cutting, and pickling to make to make the stainless steel clad layer to be used in the subsequent billet making process. In addition, in some embodiments, a substrate layer billet can be obtained first, and then the substrate layer billet can be used as the substrate layer to make assemble billet with the stainless steel clad layer in the subsequent steps; or the substrate layer billet can be obtained first, and then the substrate layer billet is subjected to cogging and rolling to obtain a substrate layer steel sheet, which is used as the substrate layer to make assemble billet with the stainless steel clad layer in the subsequent steps.

[0055] (2) Billet making: pretreatment is performed before billet making to ensure that there is no contamination on the stainless steel composite surface.

[0056] (3) Clad rolling: conventional hot rolling methods in the prior art are adopted to make hot rolled coils with different target thicknesses.

[0057] (4) Solution annealing and pickling treatment: the solution temperature is controlled to be 950-1020 C., then cooled down to room temperature at an average cooling rate of 20-50 C./s, blasting and pickling are performed to obtain the high-strength double-sided stainless steel clad sheet of which the surface status is named hot solution annealing and pickling surface NO.1.

[0058] (5) Cold rolling: a Sendzimir 20-high rolling mill is used to roll into cold rolled coils with different target thicknesses.

[0059] (6) Solution annealing, pickling and leveling treatment: the solution temperature is controlled to be 950-1020 C., and then cooled down to room temperature at an average cooling rate of 20-50 C./s to obtain the high-strength double-sided stainless steel clad sheet of which the surface status is named cold solution annealing and pickling surface 2B.

[0060] Table 2 Specific process parameters of the manufacturing methods for the high-strength double-sided stainless steel clad sheets of Examples 1-8 and Comparative Example 1.

TABLE-US-00003 Step (4) Step (6) Average Average Solution cooling Solution cooling temperature rate temperature rate Surface No. ( C.) ( C./s) ( C.) ( C./s) status Example 1 950 35 / / NO. 1 Example 2 1000 30 1000 30 2B Example 3 1000 30 960 50 2B Example 4 1000 30 / / NO. 1 Example 5 1010 33 / / NO. 1 Example 6 1000 20 950 20 2B Example 7 1020 25 / / NO. 1 Example 8 1000 20 1000 22 2B Comparative 1000 30 900 30 2B Example 1

[0061] It should be noted that in the manufacturing methods for the high-strength double-sided stainless steel clad sheets of Examples 1-8 and Comparative Example 1, if the surface status of the finally obtained high-strength double-sided stainless steel clad sheet is hot solution annealing and pickling surface NO. 1, the product was not processed in step (5) and step (6). If the surface status of the finally obtained high-strength double-sided stainless steel clad sheet is cold solution annealing and pickling surface 2B, the product went through processing in step (5) and step (6).

[0062] The mechanical properties of the high-strength double-sided stainless steel clad sheets of Examples 1-8 and Comparative Example 1 are tested to specifically test the value of yield platform during mechanical stretching, yield strength at room temperature, tensile strength at room temperature, and elongation at room temperature, wherein the mechanical tensile properties are tested according to the GB/T 6396-2008 composite steel sheet mechanical and technological property test method. The mechanical properties test results are listed in Table 3.

TABLE-US-00004 TABLE 3 Mechanical tensile properties at room temperature Value Yield Tensile Elongation of yield strength strength rate platform No. (MPa) (MPa) (A.sub.50, %) (%) Example 1 355 510 39.0 0.5 Example 2 390 540 36.0 none Example 3 375 553 32.0 none Example 4 375 505 38.0 0.5 Example 5 420 560 30.0 none Example 6 300 480 33.0 2.0 Example 7 385 590 31.0 none Example 8 405 530 34.0 none Comparative 217 439 48.0 none Example 1

[0063] It can be seen from Table 3 that the high-strength double-sided stainless steel clad sheets of Examples 1-8 have the yield strength of 300 MPa or above, which is 83-203 MPa higher than the yield strength of the high-strength double-sided stainless steel clad sheet of Comparative Example 1, and have better surface quality, which meets the requirements of market users for good surface quality and higher yield strength.

[0064] It can be seen from FIG. 1 that the microstructure of the substrate layer of the high-strength double-sided stainless steel clad sheet of Example 4 is F+P+B, and the grain size of F is about grade 7.

[0065] It can be seen from FIG. 2 that the microstructure of the stainless steel clad layer of the high-strength double-sided stainless steel clad sheet of Example 4 is a completely recrystallized austenite grain structure.

[0066] It can be seen from FIG. 3 that at the bonding interface of the high-strength double-sided stainless steel clad sheet of Example 4, an obvious &carburization layer exists on the side close to the substrate layer, which is mainly caused by the diffusion of carbon atoms in the substrate layer to the side of the stainless steel clad layer. It shows that the substrate layer and the stainless steel clad layer in the high-strength double-sided stainless steel clad sheet of Example 4 form an obvious metallurgical bond.

[0067] It should be noted that the prior art part of the protection scope of the present invention is not limited to the Examples given in this application document, and all prior art that does not contradict the solution of the present invention, including but not limited to, prior patent documents, prior publications, prior public uses, etc. can all be included in the protection scope of the present invention.

[0068] In addition, the combination of various technical features in the present invention is not limited to the combination described in the claims of the present invention or the combination described in the specific Examples. All technical features described in the present invention can be freely combined or combined in any way, unless there are contradictions between each other.

[0069] It should also be noted that the Examples listed above are only specific Examples of the present invention, Obviously, the present invention is not limited to the above Examples, and the subsequent similar changes or modifications that can be directly derived from or easily associated with the disclosure of the present invention by those skilled in the art should fall within the protection scope of the present invention.