High-strength multiphase tinned steel raw plate and manufacturing method therefor

Abstract

Disclosed are a high-strength multiphase steel tinned raw plate and a manufacturing method therefor, wherein the mass percentages of the components of the multiphase steel tinned raw plate are: 0.081%-0.14% of C, 0.2%-0.8% of Mn, 0.01%-0.09% of Al, 0.01%-0.03% of P, 0.002%-0.015% of N, also containing one or more than one of 0.001%-0.005% of B, 0.005%-0.05% of Cr, 0.001%-0.1% of Ti, 0.001%-0.2% of Nb, 0.005%-0.03% of Cu, 0.001%-0.008% of Mo, and the balance of Fe and other inevitable impurities; and satisfy: 0.21%?Mn+1.3 Cr+3.2 Mo+0.5 Cu?0.91%. The tinned raw plate has a structure comprising ferrite grains, pearlite, martensite and cementite particles, wherein the total volume fraction of the pearlite, martensite and cementite particles is 5%-20%, the volume fraction of the martensite is 1%-5%, and the martensite has a solid solution content of carbon of ?0.07%. The tinned raw plate has a high strength and better elongation, and can be used to produce a can body, a can bottom, an easy-open end and a twist-off cap, etc. of a three-piece can which has higher requirements for strength and elongation.

Claims

1. A multiphase steel tinned raw plate, having a chemical composition consisting of, by mass percentage, C: 0.081-0.14%, Mn: 0.2-0.8%, Al: 0.01-0.09%, P: 0.01-0.03%, N: 0.002-0.015%, Cu: 0.005-0.03%, one or more elements selected from the group consisting of B: 0.001-0.005%, Cr: 0.005-0.05%, Ti: 0.001-0.1%, Nb: 0.001-0.2%, and Mo: 0.001-0.008%, and a balance of Fe and unavoidable impurities, wherein the following relationship is met: 0.21%?Mn+1.3Cr+3.2Mo+0.5Cu?0.91%, wherein the multiphase steel tinned raw plate has a structure consisting of ferrite grains, pearlite, martensite and cementite particles, wherein the pearlite, martensite, and cementite particles in the structure of the multiphase steel tinned raw plate have a volume fraction of 5-20%, and the martensite in the structure of the multiphase steel tinned raw plate has a volume fraction of equal to or higher than 1% to less than 5%; and wherein, after baking at 150-300? C. for 15-60 min, the multiphase steel tinned raw plate has a yield strength Rp0.2?(400+12?DCR)MPa, and an elongation A?(25?1.2?DCR) %, wherein DCR represents a reduction rate of double cold reduction, wherein 5%?DCR?18%.

2. The multiphase steel tinned raw plate of claim 1, wherein the ferrite in the structure of the multiphase steel tinned raw plate has a grain size of ?7 ?m.

3. The multiphase steel tinned raw plate of claim 1, wherein the martensite in the structure of the multiphase steel tinned raw plate has a carbon solid solution content of ?0.07%.

4. The multiphase steel tinned raw plate of claim 1, wherein the content of N is 0.005-0.015%.

5. The multiphase steel tinned raw plate of claim 1, wherein the martensite in the structure of the multiphase steel tinned raw plate has a volume fraction of 1% to 4.8%.

6. The multiphase steel tinned raw plate of claim 2, wherein the martensite in the structure of the multiphase steel tinned raw plate has a carbon solid solution content of ?0.07%.

7. A method for manufacturing the multiphase steel tinned raw plate of claim 1, wherein the tinned raw plate has a chemical composition consisting of, by mass percentage, C: 0.081-0.14%, Mn: 0.2-0.8%, Al: 0.01-0.09%, P: 0.01-0.03%, N: 0.002-0.015%, Cu: 0.005-0.03%, one or more elements selected from the group consisting of B: 0.001-0.005%, Cr: 0.005-0.05%, Ti: 0.001-0.1%, Nb: 0.001-0.2%, and Mo: 0.001-0.008%, and a balance of Fe and unavoidable impurities, wherein the following relationship is met: 0.21%?Mn+1.3Cr+3.2Mo+0.5Cu?0.91%, wherein the tinned raw plate is subjected to continuous annealing and double cold reduction in sequence, wherein a temperature T in the continuous annealing stage is (727?100?C?30?Mn?1000?N)? 800? C.; a holding time is 30 s-50 s; a cooling rate in a zone having a temperature of 250? C. or higher is 50-90? C./s; wherein a reduction rate of the double cold reduction DCR is 5%?DCR?18%.

8. The method of claim 7 for manufacturing the multiphase steel tinned raw plate, wherein production steps prior to the continuous annealing of the tinned raw plate include smelting, hot rolling, pickling and single cold reduction.

9. The method of claim 7 for manufacturing the multiphase steel tinned raw plate, wherein: the ferrite has a grain size of ?7 ?m.

10. The method of claim 7 for manufacturing the multiphase steel tinned raw plate, wherein the martensite in the structure of the multiphase steel tinned raw plate has a carbon solid solution content of ?0.07%.

11. The method of claim 7 for manufacturing the multiphase steel tinned raw plate, wherein the content of N is 0.005-0.015%.

12. The method of claim 7 for manufacturing the multiphase steel tinned raw plate, wherein the martensite in the structure of the multiphase steel tinned raw plate has a volume fraction of 1% to 4.8%.

Description

DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a photograph of the metallographical structure of the steel plate of Example 1 according to the present disclosure.

(2) FIG. 2 is a photograph showing the topography of the pearlite+martensite+cementite particles in the metallographical structure of the steel plate of Example 1 according to the present disclosure.

DETAILED DESCRIPTION

(3) The disclosure will be further illustrated with reference to the following Examples and accompanying drawings.

(4) Table 1 lists the alloy compositions of the Examples and Comparative Examples in the present disclosure. Table 2 shows the features of the main process stages and the features of the phase compositions of the Examples and Comparative Examples in the present disclosure. Table 3 shows the yield strength and elongation properties of the Examples and Comparative Examples after baking (baking temperature 200? C.; baking time 30 min).

EXAMPLE 1

(5) The alloy composition of Example 1 is shown in Table 1: C: 0.081%, Mn: 0.5%, Al: 0.05%, P: 0.015%, N: 0.005%, B: 0.001%, Cr: 0.02%, Cu: 0.01%, Mo: 0.001%. The features of the phase composition and the production process for the strip steel are shown in Table 2: the zone of pearlite+martensite+cementite particles accounted for 10% by volume; the martensite zone accounted for 2% by volume; the grain size of ferrite was 6.5 ?m; and the carbon solid solution content in martensite was 0.082%. The temperature at the continuous annealing stage for the strip steel was 720? C.; the hold time at the annealing stage was 40 s; the cooling rate in the annealing was 60? C./s; and the reduction rate of the double cold reduction for the strip steel was 10%. The mechanical performances of the final strip steel baked at 200? C. for 30 min are shown in Table 3: the yield strength Rp0.2 was 564 MPa; and the elongation at break was 18%.

(6) As known from FIGS. 1 and 2, the structure of the tinned raw plate in this Example was consisting of ferrite grains, pearlite, martensite and cementite particles, wherein the zone of pearlite+martensite+cementite accounted for 10% by volume; the martensite zone accounted for 2% by volume; the grain size of ferrite was 6.5 ?m (the grain size of ferrite was measured from the metallographical structure shown by FIG. 1 in the transverse direction using the linear intercept method); and the carbon solid solution content in martensite was 0.082%.

EXAMPLE 2

(7) The alloy composition of Example 2 was: C: 0.081%, Mn: 0.5%, Al: 0.05%, P: 0.01%, N: 0.005%, B: 0.003%, Cr: 0.05%, Ti: 0.005%, Nb: 0.2%, Cu: 0.01%, Mo: 0.005%. The features of the phase composition of the strip steel were: the zone of pearlite+martensite+cementite particles accounted for 13% by volume; the martensite zone accounted for 4% by volume; the grain size of ferrite was 6.5 ?m; and the carbon solid solution content in martensite was 0.095%. The temperature at the continuous annealing stage for the strip steel was 750? C.; the hold time at the annealing stage was 40 s; the cooling rate in the annealing was 90? C./s; and the reduction rate of the double cold reduction for the strip steel was 5%. The mechanical performances of the final strip steel baked at 200? C. for 30 min: the yield strength Rp0.2 was 512 MPa; and the elongation at break was 20.9%.

EXAMPLE 3

(8) The alloy composition of Example 3 was: C: 0.135%, Mn: 0.2%, Al: 0.05%, P: 0.01%, N: 0.005%, B: 0.003%, Cr: 0.005%, Cu: 0.03%, Mo: 0.005%. The features of the phase composition of the strip steel were: the zone of pearlite+martensite+cementite particles accounted for 5% by volume; the martensite zone accounted for 1.2% by volume; the grain size of ferrite was 5.3 ?m; and the carbon solid solution content in martensite was 0.071%. The temperature at the continuous annealing stage for the strip steel was 705? C.; the hold time at the annealing stage was 30 s; the cooling rate in the annealing was 50? C./s; and the reduction rate of the double cold reduction for the strip steel was 5%. The mechanical performances of the final strip steel baked at 200? C. for 30 min: the yield strength Rp0.2 was 482 MPa; and the elongation at break was 20.2%.

EXAMPLE 4

(9) The alloy composition of Example 4 was: C: 0.14%, Mn: 0.5%, Al: 0.01%, P: 0.015%, N: 0.015%, B: 0.003%, Cr: 0.02%, Ti: 0.1%, Cu: 0.01%, Mo: 0.008%. The features of the phase composition of the strip steel were: the zone of pearlite+martensite+cementite particles accounted for 19% by volume; the martensite zone accounted for 4.8% by volume; the grain size of ferrite was 6.2 ?m; and the carbon solid solution content in martensite was 0.1%. The temperature at the continuous annealing stage for the strip steel was 800? C.; the hold time at the annealing stage was 30 s; the cooling rate in the annealing was 90? C./s; and the reduction rate of the double cold reduction for the strip steel was 18%. The mechanical performances of the final strip steel baked at 200? C. for 30 min: the yield strength Rp0.2 was 650 MPa; and the elongation at break was 5.5%.

EXAMPLE 5

(10) The alloy composition of Example 5 was: C: 0.1%, Mn: 0.8%, Al: 0.035%, P: 0.015%, N: 0.015%, B: 0.005%, Cr: 0.02%, Ti: 0.001%, Cu: 0.01%. The features of the phase composition of the strip steel were: the zone of pearlite+martensite+cementite particles accounted for 14% by volume; the martensite zone accounted for 1.5% by volume; the grain size of ferrite was 6.8 ?m; and the carbon solid solution content in martensite was 0.081%. The temperature at the continuous annealing stage for the strip steel was 750? C.; the hold time at the annealing stage was 50 s; the cooling rate in the annealing was 50? C./s; and the reduction rate of the double cold reduction for the strip steel was 10%. The mechanical performances of the final strip steel baked at 200? C. for 30 min: the yield strength Rp0.2 was 544 MPa; and the elongation at break was 15%.

EXAMPLE 6

(11) The alloy composition of Example 6 was: C: 0.1%, Mn: 0.5%, Al: 0.09%, P: 0.03%, N: 0.005%, B: 0.003%, Cr: 0.02%, Ti: 0.005%, Nb: 0.001, Cu: 0.005%. The features of the phase composition of the strip steel were: the zone of pearlite+martensite+cementite particles accounted for 5% by volume; the martensite zone accounted for 2.5% by volume; the grain size of ferrite was 5.5 ?m; and the carbon solid solution content in martensite was 0.09%. The temperature at the continuous annealing stage for the strip steel was 700? C.; the hold time at the annealing stage was 30 s; the cooling rate in the annealing was 90? C./s; and the reduction rate of the double cold reduction for the strip steel was 12%. The mechanical performances of the final strip steel baked at 200? C. for 30 min: the yield strength Rp0.2 was 597 MPa; and the elongation at break was 13%.

EXAMPLE 7

(12) The alloy composition of Example 7 was: C: 0.1%, Mn: 0.5%, Al: 0.09%, P: 0.03%, N: 0.002%, B: 0.003%, Cr: 0.02%, Ti: 0.005%, Cu; 0.01%. The features of the phase composition of the strip steel were: the zone of pearlite+martensite+cementite particles accounted for 14% by volume; the martensite zone accounted for 3.5% by volume; the grain size of ferrite was 6.2 ?m; and the carbon solid solution content in martensite was 0.089%. The temperature at the continuous annealing stage for the strip steel was 750? C.; the hold time at the annealing stage was 40 s; the cooling rate in the annealing was 80? C./s; and the reduction rate of the double cold reduction for the strip steel was 10%. The mechanical performances of the final strip steel baked at 200? C. for 30 min: the yield strength Rp0.2 was 575 MPa; and the elongation at break was 17%.

EXAMPLE 8

(13) The alloy composition of Example 8 was: C: 0.1%, Mn: 0.5%, Al: 0.05%, P: 0.015%, N: 0.005%, B: 0.003%, Cr: 0.02%, Ti: 0.005%, Cu: 0.01%. The features of the phase composition of the strip steel were: the zone of pearlite+martensite+cementite particles accounted for 19% by volume; the martensite zone accounted for 1.2% by volume; the grain size of ferrite was 6.7 ?m; and the carbon solid solution content in martensite was 0.080%. The temperature at the continuous annealing stage for the strip steel was 800? C.; the hold time at the annealing stage was 30 s; the cooling rate in the annealing was 50? C./s; and the reduction rate of the double cold reduction for the strip steel was 5%. The mechanical performances of the final strip steel baked at 200? C. for 30 min: the yield strength Rp0.2 was 497 MPa; and the elongation at break was 20.3%.

COMPARATIVE EXAMPLE 1

(14) The alloy composition of Comparative Example 1 was: C: 0.07%, Mn: 0.5%, Al: 0.09%, P: 0.03%, N: 0.002%, B: 0.003%, Cr: 0.02%, Ti: 0.005%, Cu: 0.04%. The features of the phase composition of the strip steel were: no pearlite+martensite zone; the grain size of ferrite was 5.2 ?m. The temperature at the continuous annealing stage for the strip steel was 690? C.; the hold time at the annealing stage was 40 s; the cooling rate in the annealing was 50? C./s; and the reduction rate of the double cold reduction for the strip steel was 19%. The mechanical performances of the final strip steel baked at 200? C. for 30 min: the yield strength Rp0.2 was 645 MPa; and the elongation at break was 0.5%.

COMPARATIVE EXAMPLE 2

(15) The alloy composition of Comparative Example 2 was: C: 0.1%, Mn: 0.1%, Al: 0.05%, P: 0.008%, N: 0.005%, B: 0.01%, Cr: 0.02%, Ti: 0.005%, Cu: 0.01%. The features of the phase composition of the strip steel were: the zone of pearlite+martensite+cementite particles accounted for 12% by volume; the martensite zone accounted for 3.2% by volume; the grain size of ferrite was 8.2 ?m; and the carbon solid solution content in martensite was 0.068%. The temperature at the continuous annealing stage for the strip steel was 750? C.; the hold time at the annealing stage was 60 s; the cooling rate in the annealing was 50? C./s; and the reduction rate of the double cold reduction for the strip steel was 10%. The mechanical performances of the final strip steel baked at 200? C. for 30 min: the yield strength Rp0.2 was 501.3 MPa; and the elongation at break was 8%.

COMPARATIVE EXAMPLE 3

(16) The alloy composition of Comparative Example 3 was: C: 0.1%, Mn: 0.5%, Al: 0.005%, P: 0.05%, N: 0.002%, B: 0.003%, Cr: 0.02%, Ti: 0.005%, Cu: 0.01%, Mo: 0.01%. The features of the phase composition of the strip steel were: the zone of pearlite+martensite+cementite particles accounted for 14% by volume; the martensite zone accounted for 7.8% by volume; the grain size of ferrite was 5.7 ?m; and the carbon solid solution content in martensite was 0.12%. The temperature at the continuous annealing stage for the strip steel was 750? C.; the hold time at the annealing stage was 40 s; the cooling rate in the annealing was 120? C./s; and the reduction rate of the double cold reduction for the strip steel was 5%. The mechanical performances of the final strip steel baked at 200? C. for 30 min: the yield strength Rp0.2 was 587 MPa; and the elongation at break was 7.8%.

COMPARATIVE EXAMPLE 4

(17) The alloy composition of Comparative Example 4 was: C: 0.13%, Mn: 0.5%, Al: 0.05%, P: 0.015%, N: 0.005%, B: 0.003%, Cr: 0.02%, Ti: 0.005%, Cu: 0.01%. The features of the phase composition of the strip steel were: the zone of pearlite+martensite+cementite particles accounted for 21.6% by volume; the martensite zone accounted for 6.9% by volume; the grain size of ferrite was 8.4 ?m; and the carbon solid solution content in martensite was 0.1%. The temperature at the continuous annealing stage for the strip steel was 820? C.; the hold time at the annealing stage was 40 s; the cooling rate in the annealing was 80? C./s; and the reduction rate of the double cold reduction for the strip steel was 10%. The mechanical performances of the final strip steel baked at 200? C. for 30 min: the yield strength Rp0.2 was 555.8 MPa; and the elongation at break was 10.2%.

COMPARATIVE EXAMPLE 5

(18) The alloy composition of Comparative Example 5 was: C: 0.10%, Mn: 0.5%, Al: 0.05%, P: 0.015%, N: 0.02%, B: 0.003%, Cr: 0.10%, Ti: 0.2%, Cu: 0.01%. The features of the phase composition of the strip steel were: the zone of pearlite+martensite+cementite particles accounted for 4% by volume; the martensite zone accounted for 0.6% by volume; the grain size of ferrite was 5.2 ?m; and the carbon solid solution content in martensite was 0.07%. The temperature at the continuous annealing stage for the strip steel was 750? C.; the hold time at the annealing stage was 20 s; the cooling rate in the annealing was 80? C./s; and the reduction rate of the double cold reduction for the strip steel was 2%. The mechanical performances of the final strip steel baked at 200? C. for 30 min: the yield strength Rp0.2 was 612.3 MPa; and the elongation at break was 5.9%.

COMPARATIVE EXAMPLE 6

(19) The alloy composition of Comparative Example 6 was: C: 0.15%, Mn: 0.9%, Al: 0.05%, P: 0.015%, N: 0.01%, Cr: 0.10%, Ti: 0.2%, Nb: 0.3%. The features of the phase composition of the strip steel were: the pearlite zone accounted for 13% by volume; the martensite zone accounted for 0% by volume; and the grain size of ferrite was 7.6 ?m. The temperature at the continuous annealing stage for the strip steel was 750? C.; the hold time at the annealing stage was 40 s; the cooling rate in the annealing was 30? C./s; and no double cold reduction was conducted. The mechanical performances of the final strip steel baked at 200? C. for 30 min: the yield strength Rp0.2 was 454.8 MPa; and the elongation at break was 20.8%.

(20) TABLE-US-00001 TABLE 1 (unit: mass percentage) C Mn Al P N B Cr Ti Nb Cu Mo Ex. 1 0.081 0.5 0.05 0.015 0.005 0.001 0.02 0 0 0.01 0.001 Ex. 2 0.081 0.5 0.05 0.01 0.005 0.003 0.05 0.005 0.2 0.01 0.005 Ex. 3 0.135 0.2 0.05 0.01 0.005 0.003 0.005 0 0 0.03 0.005 Ex. 4 0.14 0.5 0.01 0.015 0.015 0.003 0.02 0.1 0 0.01 0.008 Ex. 5 0.10 0.8 0.035 0.015 0.015 0.005 0.02 0.001 0 0.01 0 Ex. 6 0.10 0.5 0.09 0.03 0.005 0.003 0.02 0.005 0.001 0.005 0 Ex. 7 0.10 0.5 0.09 0.03 0.002 0.003 0.02 0.005 0 0.01 0 Ex. 8 0.10 0.5 0.05 0.015 0.005 0.003 0.02 0.005 0 0.01 0 Comp. 0.07 0.5 0.09 0.03 0.002 0.003 0.02 0.005 0 0.04 0 Ex. 1 Comp. 0.10 0.1 0.05 0.008 0.005 0.01 0.02 0.005 0 0.01 0 Ex. 2 Comp. 0.10 0.5 0.005 0.05 0.002 0.003 0.02 0.005 0 0.01 0.01 Ex. 3 Comp. 0.13 0.5 0.05 0.015 0.005 0.003 0.02 0.005 0 0.01 0 Ex. 4 Comp. 0.10 0.5 0.05 0.015 0.020 0.003 0.10 0.2 0 0.01 0 Ex. 5 Comp. 0.15 0.9 0.05 0.015 0.01 0 0.10 0.2 0.3 0 0 Ex. 6

(21) TABLE-US-00002 TABLE 2 Phase Features Production Process Pearlite + C solid Reduction martensite + solution Continuous Hold time Cooling rate of cementite Ferrite content in annealing in rate in double cold particles Martensite grain size martensite temperature annealing annealing reduction (%) (%) (?m) (%) (? C.) (s) (? C./s) (%) Ex. 1 10 2 6.5 0.082 720 40 60 10 Ex. 2 13 4 6.5 0.095 750 40 90 5 Ex. 3 5 1.2 5.3 0.071 705 30 50 5 Ex. 4 19.0 4.8 6.2 0.1 800 30 90 18 Ex. 5 14 1.5 6.8 0.081 750 50 50 10 Ex. 6 5 2.5 5.5 0.090 700 30 90 12 Ex. 7 14 3.5 6.2 0.089 750 40 80 10 Ex. 8 19.0 1.2 6.7 0.080 800 30 50 5 Comp. 0 0 5.2 690 40 50 19 Ex. 1 Comp. 12 3.2 8.2 0.068 750 60 50 10 Ex. 2 Comp. 14 7.8 5.7 0.12 750 40 120 5 Ex. 3 Comp. 21.6 6.9 8.4 0.10 820 40 80 10 Ex. 4 Comp. 4 0.6 5.2 0.070 750 20 80 2 Ex. 5 Comp. 13 0 7.6 750 40 30 0 Ex. 6

(22) TABLE-US-00003 TABLE 3 Rp0.2(MPa) A(%) Ex. 1 564 18 Ex. 2 512 20.9 Ex. 3 482 20.2 Ex. 4 650 5.5 Ex. 5 544 15 Ex. 6 597 13 Ex. 7 575 17 Ex. 8 497 20.3 Comp. Ex. 1 645 0.5 Comp. Ex. 2 501.3 8 Comp. Ex. 3 587 7.8 Comp. Ex. 4 555.8 10.2 Comp. Ex. 5 612.3 5.9 Comp. Ex. 6 454.8 20.8