Production method for inline increase in precipitation toughening effect of Ti microalloyed hot-rolled high-strength steel

Abstract

There is provided a production method for on-line improving precipitation strengthening effect of Ti microalloyed hot-rolled high-strength steel, comprising: casting a molten steel with microalloying element Ti added to obtain an ingot; after heating the ingot, subjecting it to rough rolling, finish rolling, laminar cooling and coiling to obtain a hot-rolled coil; after unloading the coil, covering the coil on-line with an insulating enclosure and moving it into a steel coil warehouse along with a transport chain; after a specified period of on-line insulating time, removing the coil from the insulating enclosure, and cooling it to room temperature in air, wherein the microalloying element Ti has a content of ≥0.03 wt %; the coiling is performed at a temperature of 500-700° C.; said covering on-line with an insulating enclosure means each hot-rolled coil is individually covered with an independent, closed insulating enclosure unit within 60 minutes after unloading; the on-line insulating time is ≥60 minutes. The method of the present disclosure is characterized by low cost and high efficiency, and is not affected by surroundings.

Claims

1. A production method for improving precipitation strengthening effect of Ti microalloyed hot-rolled high-strength steel, comprising: casting a molten steel with microalloying element Ti added to obtain an ingot; after heating the ingot, subjecting it to rough rolling, finish rolling, laminar cooling and coiling to obtain a hot-rolled coil; after unloading the hot-rolled coil, covering each of the hot-rolled coil individually with an independent, closed insulating enclosure unit within 60 minutes and moving it into a steel coil warehouse along with a transport chain; after an insulating time of ≥60 minutes, removing the coil from the insulating enclosure, and cooling it to room temperature in air, wherein the microalloying element Ti has a content of ≥0.03 wt %; the coiling is performed at a temperature of 500-700° C.

2. The production method for improving precipitation strengthening effect of Ti microalloyed hot-rolled high-strength steel according to claim 1, wherein the microalloying element Ti has a content of 0.03-0.10 wt %.

3. The production method for improving precipitation strengthening effect of Ti microalloyed hot-rolled high-strength steel according to claim 1, wherein the ingot is heated at a temperature of ≥1200° C., and a soaking time is ≥60 minutes.

4. The production method for improving precipitation strengthening effect of Ti microalloyed hot-rolled high-strength steel according to claim 1, wherein the ingot is heated at a temperature of 1200-1300° C., and the soaking time is 1-2 hours.

5. The production method for improving precipitation strengthening effect of Ti microalloyed hot-rolled high-strength steel according to claim 1, wherein the rough rolling is performed at a temperature of 1000-1200° C., wherein 3-8 passes of reciprocating rolling are performed, and a cumulative deformation is ≥50%.

6. The production method for improving precipitation strengthening effect of Ti microalloyed hot-rolled high-strength steel according to claim 1, wherein the finish rolling is performed with 6-7 passes of continuous rolling, wherein a cumulative deformation is ≥80%, and a final rolling temperature is 800-900° C.

7. The production method for improving precipitation strengthening effect of Ti microalloyed hot-rolled high-strength steel according to claim 1, wherein each hot-rolled coil is individually covered with an insulating enclosure within 20 minutes after it is unloaded.

8. The production method for improving precipitation strengthening effect of Ti microalloyed hot-rolled high-strength steel according to claim 1, wherein the hot-rolled coil is cooled at a cooling rate of ≤15° C./hour in the insulating enclosure.

9. The production method for improving precipitation strengthening effect of Ti microalloyed hot-rolled high-strength steel according to claim 1, wherein the insulating time of the hot-rolled coil is 1-5 hours.

Description

DETAILED DESCRIPTION

(1) The disclosure will be further illustrated with reference to the following specific Examples.

(2) Table 1 shows the key process parameters of the Examples in the present disclosure, Table 2 shows the key process parameters of the Comparative Examples in the present disclosure, and Table 3 shows the properties of the steel coils of the Examples and the Comparative Examples in the present disclosure.

(3) The process flow for the Examples in the present disclosure is as follows: providing an ingot comprising ≥0.03% Ti.fwdarw.heating the ingot.fwdarw.rough rolling.fwdarw.finish rolling.fwdarw.laminar cooling.fwdarw.coiling.fwdarw.covering with an insulating enclosure on-line.fwdarw.removing from the insulating enclosure, wherein the key process parameters are shown in Table 1.

(4) The process flow for the Comparative Examples in the present disclosure is as follows: providing an ingot comprising ≥0.03% Ti.fwdarw.heating the ingot.fwdarw.rough rolling.fwdarw.finish rolling.fwdarw.laminar cooling.fwdarw.coiling.fwdarw.slow cooling the steel coil in stack, wherein the key process parameters are shown in Table 2.

(5) TABLE-US-00001 TABLE 1 Steel coil Ti Heating Rough rolling Final rolling Coiling Covering Insulating thickness content temperature temperature temperature Temperature time time Ex. (mm) (%) (° C.) (° C.) (° C.) (° C.) (min) (h) 1 1.5 0.086 1255 1113 886 603 20 4 2 4.5 0.090 1261 1116 892 583 16 4 3 1.5 0.072 1261 1118 862 612 10 2 4 6.0 0.077 1245 1037 857 591 38 2 5 2.0 0.060 1249 1082 863 607 21 2 6 2.8 0.034 1258 1094 870 586 17 2

(6) TABLE-US-00002 TABLE 2 Steel coil Ti Heating Rough rolling Final rolling Coiling thickness content temperature temperature temperature Temperature Comp. Ex. (mm) (%) (° C.) (° C.) (° C.) (° C.) 1 1.5 0.086 1251 1117 897 608 2 4.5 0.090 1264 1115 883 582 3 1.5 0.072 1260 1123 861 610 4 6.0 0.077 1243 1042 853 593 5 4.0 0.060 1252 1075 869 601 6 2.8 0.034 1261 1107 874 588

(7) TABLE-US-00003 TABLE 3 Yield Tensile strength (MPa) strength (MPa) Elongation/% Ex. 1 792 835 23 2 773 825 22 3 771 813 21 4 636 716 20 5 620 661 26 6 573 672 23 Comp. Ex. 1 761 788 20 2 754 811 22 3 743 787 22 4 604 695 21 5 587 643 26 6 533 641 22

(8) As can be seen from the data of the Examples and Comparative Examples in Table 3, in comparison with the method employing slow cooling of steel coils in stack, the Ti micro-alloyed hot-rolled high-strength steel produced by the method proposed by the present disclosure has a yield strength increase of 10-40 MPa, a tensile strength increase of 10-50 MPa, and a comparable elongation at break, indicating that the method proposed by the present disclosure can effectively improve the precipitation strengthening effect of TiC without compromising the plasticity index of the material.

(9) The embodiments of the present disclosure are not limited to the foregoing examples. Any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present disclosure should all be equivalent alternatives, all falling in the protection scope of the present disclosure.