TEMPERING-FREE WEAR-RESISTANT HOT ROLLED STRIP AND METHOD FOR PRODUCING SAME

Abstract

A tempering-free wear-resistant hot rolled strip, includes components in percentage by weight: 0.08-0.22% of C, 0.1-0.55% of Si, 0.8-1.5% of Mn, less than or equal to 0.012% of P, less than or equal to 0.005% of S, 0.01-0.055% of Als, 0.005-0.019% of Ti, and less than or equal to 0.007% of N. A method for producing the same includes: desulfurizing molten iron, smelting desulfurized molten iron, and casting into a blank; heating the casting blank; performing rough rolling; performing finish rolling; performing rapid cooling; performing coiling; and performing conventional temper rolling. According to the present disclosure, on the premise that the tensile strength of a steel plate is greater than or equal to 1100 MPa and the elongation is greater than or equal to 12%, the steel plate has a surface Brinell hardness of 330-390 and a core hardness that is 95% or above of the surface hardness.

Claims

1. A tempering-free wear-resistant hot rolled strip, comprising the following components in percentage by weight: 0.08-0.22% of C, 0.1-0.55% of Si, 0.8-1.5% of Mn, less than or equal to 0.012% of P, less than or equal to 0.005% of S, 0.01-0.055% of Als, 0.005-0.019% of Ti, less than or equal to 0.007% of N, and the balance of Fe and impurities, and a structure is lath martensite.

2. The tempering-free wear-resistant hot rolled strip according to claim 1, wherein a weight percentage of B added is less than or equal to 0.005%.

3. The tempering-free wear-resistant hot rolled strip according to claim 1, wherein a weight percentage of C is 0.08-0.15%.

4. The tempering-free wear-resistant hot rolled strip according to claim 1, wherein a weight percentage of Mn is 0.08-1.38%.

5. The tempering-free wear-resistant hot rolled strip according to claim 1, wherein a weight percentage of Ti is 0.005-0.015%.

6. The tempering-free wear-resistant hot rolled strip according to claim 1, wherein a weight percentage of Als is 0.01-0.048%.

7. The tempering-free wear-resistant hot rolled strip according to claim 1, wherein a weight percentage of Si is 0.10-0.46%.

8. A method for producing the tempering-free wear-resistant hot rolled strip according to claim 1, comprising the following steps: 1) desulfurizing molten iron, smelting the desulfurized molten iron, and casting into a blank; 2) heating the casting blank: wherein a heating temperature is controlled at 1220-1270° C., and the temperature is maintained for at least 60 min; a total duration in a furnace is controlled to be 140 min or more; and a temperature difference in a plate thickness direction is controlled to not exceed 5° C.; 3) performing rough rolling, wherein a rough rolling end temperature is controlled at 1050-1110° C., and a thickness of an intermediate plate at the end is 30-50 mm; 4) performing finish rolling, wherein an initial rolling temperature is controlled at 950-1050° C., a rolling speed is controlled to be 2-7 m/s, and a final rolling temperature of the finish rolling is controlled to be 830-880° C.; 5) performing rapid cooling, namely cooling to 350° C. or below at a cooling rate of 40-150° C./s, and controlling an upper and lower cooling water ratio to be 45:55-75:80; 6) performing coiling, wherein a coiling temperature is controlled at 300-400° C., and a coiling tension is controlled to be 10-20 t; and 7) performing conventional temper rolling to control a waviness to not exceed 4.5 mm/m.

9. The method according to claim 8, wherein the casting blank is heated at 1228-1263° C.

10. The method according to claim 8, wherein the coiling is performed at 325-380° C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] FIG. 1 is a metallographic structure diagram of steel of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] The present disclosure is described in detail below:

[0044] Table 1 shows values of chemical components in Embodiments and control groups of the present disclosure;

[0045] Table 2 shows values of main process parameters in Embodiments and control groups of the present disclosure; and

[0046] Table 3 shows property detection and results in Embodiments and control groups of the present disclosure.

[0047] The embodiments achieve production according to the following steps:

[0048] 1) desulfurizing molten iron, smelting the desulfurized molten iron, and casting into a blank;

[0049] 2) heating the casting blank: a heating temperature is controlled at 1220-1270° C., and the temperature is maintained for at least 60 min; a total duration in a furnace is controlled to be 140 min or more; and a temperature difference in a plate thickness direction is controlled to not exceed 5° C.;

[0050] 3) performing rough rolling, wherein a rough rolling end temperature is controlled at 1050-1110° C., and a thickness of an intermediate plate at the end is 30-50 mm;

[0051] 4) performing finish rolling, wherein an initial rolling temperature is controlled at 950-1050° C., a rolling speed is controlled to be 2-7 m/s, and a final rolling temperature of the finish rolling is controlled to be 830-880° C.;

[0052] 5) performing rapid cooling, namely cooling to 350° C. or below at a cooling rate of 40-150° C./s, and an upper and lower cooling water ratio is controlled to be 45:55-75:80;

[0053] 6) performing coiling, wherein a coiling temperature is controlled at 300-400° C., and a coiling tension is controlled to be 10-20 t; and

[0054] 7) performing conventional temper rolling to control a waviness to not exceed 4.5 mm/m.

TABLE-US-00001 TABLE 1 Chemical components (wt %) in Embodiments and control groups of the present disclosure Si Mn P S Cr Mo Nb Als Ti B N Group C/% % % % % % % % % % % % 1 0.08 0.39 1.32 0.012 0.003 — — — 0.010 0.012 0.0012 0.005 2 0.21 0.14 0.95 0.007 0.002 — — — 0.017 0.027 0.0024 0.006 3 0.178 0.10 1.36 0.011 0.004 — — — 0.038 0.024 0.0031 0.004 4 0.127 0.25 1.23 0.006 0.005 — — — 0.034 0.005 0.0010 0.005 5 0.186 0.26 1.09 0.009 0.002 — — — 0.014 0.008 0.0024 0.004 6 0.22 0.72 0.80 0.008 0.005 — — — 0.058 0.009 0 0.006 7 0.109 0.18 0.87 0.007 0.003 — — — 0.019 0.011 0.0013 0.003 8 0.116 0.29 1.32 0.008 0.005 — — — 0.029 0.009 0.0032 0.005 9 0.106 0.42 1.14 0.010 0.003 — — — 0.018 0.008 0.0050 0.006 10 0.163 0.16 1.58 0.011 0.004 — — — 0.060 0.030 0.0024 0.007 Control 0.16 0.35 1.5 0.010 0.003 0.65 — 0.015 0.021 0.015 0.0015 0.005 Group 1 Control 0.15 0.32 1.2 0.009 0.002 0.58 0.30 — 0.017 0.0018 0.005 Group 2

TABLE-US-00002 TABLE 2 Main process parameters in Embodiments and control groups of the present disclosure Total duration Rough Initial rolling Heating Heat in a rolling End Thickness of temperature Final rolling temperature preservation furnace temperature intermediate of finish temperature Group ° C. time min min ° C. slab mm rolling ° C. ° C. 1 1259 87 157 1110 45 983 873 2 1270 71 140 1077 30 950 830 3 1252 60 162 1099 38 964 839 4 1239 73 146 1050 32 954 845 5 1243 64 150 1074 37 980 835 6 1220 80 144 1062 50 1050 880 7 1246 74 163 1075 42 954 836 8 1224 64 155 1088 38 954 831 9 1243 71 145 1109 41 978 850 10 1223 70 152 1085 49 974 870 Control 1284 90 166 1080 45 1003 880 Group 1 Control 1260 101 175 1060 58 938 850 Group 2 Rolling Cooling Upper and Cross side Water Coiling Coiling speed rate lower water water spraying pressure temperature tension Group m/s ° C./s ratio aperture bar ° C. t Quenching 1 6.1 122 45:55 Fully opened 1.8 333 23 Online 2 5.6 118 50:60 Fully opened 0.8 377 13 Online 3 3.4 100 50:55 Fully opened 0.9 318 20 Online 4 6.3 87 65:70 Fully opened 1.1 334 24 Online 5 6.1 78 70:80 Fully opened 1.4 311 12 Online 6 7.0 40 75:80 Fully opened 1.5 336 29 Online 7 4.2 143 60:70 Fully opened 1.9 303 16 Online 8 4.5 120 60:70 Fully opened 1.0 319 27 Online 9 3.2 140 45:50 Fully opened 0.9 315 24 Online 10 2.1 150 70:75 Fully opened 0.9 372 23 Online Control 5.6 22 30:40 Fully opened 0.9 640 30 890° C.*30 Group 1 min Control 6.2 26 35:45 Fully opened 1.2 610 28 890° C.*36 Group 2 min

TABLE-US-00003 TABLE 3 Mechanical property detection results in Embodiments and control groups of the present disclosure W10/3000 Tensile strength Elongation A W10/3000 (core) Group MPa % (surface) HB HB Cold bending property 1 1128 12 348 341 375 343 D = 4a, qualified at 180° 2 1160 13 347 350 348 334 D = 4a, qualified at 180° 3 1193 14 371 343 361 348 D = 4a, qualified at 180° 4 1171 12 351 362 347 339 D = 4a, qualified at 180° 5 1203 14 360 369 362 356 D = 4a, qualified at 180° 6 1124 12 366 379 346 356 D = 4a, qualified at 180° 7 1184 14 359 353 365 348 D = 4a, qualified at 180° 8 1206 13 372 372 348 348 D = 4a, qualified at 180° 9 1205 12 374 348 370 351 D = 4a, qualified at 180° 10 1217 13 365 377 358 363 D = 4a, qualified at 180° Control 1260 10.5 390 398 400 375 D = 4a, qualified at 90° Group 1 cracked at 180° Control 1201 11 410 412 418 375 D = 4a, qualified at 90° Group 2 cracked at 180°

[0055] It can be seen from Table 3 that under the condition that the chemical components are fewer (without Cr, Nb and Mo), the Brinell hardness is 341-379; the core hardness in the thickness direction is at least 96% or above of the surface hardness; and the cold bending property can satisfy D=4a, qualified at 180°. However, since the alloy content in the control groups is higher, the core hardness can only be 90-94% of the surface hardness, and the cold bending property can only satisfy D=4a, qualified at 90°.

[0056] The above embodiments are only optimal examples, but are not intended to limit the implementations of the present disclosure.