KR101304644B1 - High strength steel plate having excellent fatigue crack arrestability and manufacturing method the same - Google Patents

Abstract

The present invention is in weight%, carbon (C): 0.02 to 0.12%, silicon (Si): 0.01 to 0.6%, manganese (Mn): 0.3 to 2.5%, aluminum (Al): 0.005 to 0.5%, niobium (Nb) ): 0.005 to 0.10%, boron (B): 5 to 40 ppm, titanium (Ti): 0.005 to 0.1%, nitrogen (N): 15 to 150 ppm, phosphorus (P): 0.02% or less, sulfur (S): 0.01 Fatigue crack propagation inhibiting properties comprising less than%, residual iron (Fe) and other unavoidable impurities, microstructure comprises 5.57-8% of phase martensite (MA) and mixed tissue of residual granular bainite and bainitic ferrite This is an excellent high strength steel sheet.

Fatigue crack, phase martensite, high strength, cooling end temperature

Description

High strength steel plate with excellent fatigue crack propagation suppression and its manufacturing method {HIGH STRENGTH STEEL PLATE HAVING EXCELLENT FATIGUE CRACK ARRESTABILITY AND MANUFACTURING METHOD THE SAME}

The present invention relates to a steel sheet used in a super-large welded structure and a method for manufacturing the same, and more particularly, to a high strength steel sheet and a method for manufacturing the same, when fatigue cracking occurs under repeated stresses. will be.

In recent years, steel structures are becoming increasingly large in size, and the use of high-strength steels is increasing according to this trend. As the strength of the steel increases, the stress concentrated around the crack also increases, so the crack propagation speed of the steel also increases.

In the fatigue process of steel, cracks occur at stress concentrations and cracks are propagated. In particular, in the case of a welded structure, a large number of defects are present in the weld metal, so it is practical to completely prevent the occurrence of fatigue cracks. It is impossible. Therefore, in order to improve the fatigue life of the welded structure, it is important to slow the crack growth rate from the existing state rather than to prevent the crack generation itself.

Japanese Patent Application Laid-Open No. 2000-17379 describes such a technique. When this technique is referred to as ND as the vertical direction of the steel plate surface, crystal grains in which the (100) plane of the ferrite crystal has a direction parallel to the ND direction, The boundary between grains whose (111) planes have an orientation parallel to ND is equal to the ferrite (111) plane fraction and (100) in the measurement plane that crosses at least one place at least 30 μm along the crack propagation direction or is parallel to the steel plate surface. The ratio of the ratio of the surface fraction to 1.25 to 2.0 relates to a steel sheet having improved fatigue crack propagation suppression characteristics.

The present invention is to provide a high-strength steel sheet excellent in fatigue crack suppression characteristics that slow down the growth rate of fatigue cracks generated by the cyclic stress applied to the weld structure and a method of manufacturing the same.

In one embodiment, the present invention provides, by weight, carbon (C): 0.02 to 0.12%, silicon (Si): 0.01 to 0.6%, manganese (Mn): 0.3 to 2.5%, aluminum (Al): 0.005 to 0.5 %, Niobium (Nb): 0.005 to 0.10%, boron (B): 5 to 40 ppm, titanium (Ti): 0.005 to 0.1%, nitrogen (N): 15 to 150 ppm, phosphorus (P): 0.02% or less, sulfur (S): 0.01% or less, containing residual iron (Fe) and other unavoidable impurities, the microstructure is fatigue crack growth, a mixed structure of 5.57-8% of the phase martensite (MA) and the residual granular bainite and bainitic ferrite Provided is a high strength steel sheet having excellent suppression characteristics.

The steel sheet is chromium (Cr): 0.05 ~ 1.0%, molybdenum (Mo): 0.01 ~ 1.0%, nickel (Ni): 0.01 ~ 2.0%, copper (Cu): 0.01 ~ 1.0% and vanadium (V): 0.005 ~ It may further comprise one or two or more of 0.3%.

The grain size of the island martensite is preferably 5 µm or less.

The fatigue crack growth rate of the steel sheet is preferably 2.5 * 10 ^-5 mm / cycle or less.

As another embodiment of the present invention, in weight%, carbon (C): 0.02 to 0.12%, silicon (Si): 0.01 to 0.6%, manganese (Mn): 0.3 to 2.5%, aluminum (Al): 0.005 to 0.5 %, Niobium (Nb): 0.005 to 0.10%, boron (B): 5 to 40 ppm, titanium (Ti): 0.005 to 0.1%, nitrogen (N): 15 to 150 ppm, phosphorus (P): 0.02% or less, sulfur (S): reheating the slab containing 0.01% or less, balance iron (Fe) and other unavoidable impurities at 1050-1250 ° C .; Roughly rolling the reheated slab at an austenite recrystallization temperature (Tnr) ˜1250 ° C .; Finishing the roughly rolled steel sheet in the range of bainite transformation start temperature (Bs) to Tnr; And it provides a method of producing a high strength steel sheet having excellent fatigue crack propagation suppression characteristics including a cooling step of cooling the finishing rolled steel sheet at 630 ~ 700 ℃ at a cooling rate of 2 ~ 10 ℃ / s.

The present invention may provide a steel sheet having a fatigue crack growth rate of 2 * 10 ^-5 mm / cycle or less and a tensile strength of 600 MPa or more.

The present invention controls the component system of the steel sheet, and control the cooling end temperature after rolling to form a fraction of the island martensite having a higher strength than the matrix structure, fatigue fatigue changes the direction of travel at the interface between the island martensite and matrix structure It is a high strength steel sheet with excellent fatigue crack propagation suppression property which lowers the fatigue crack propagation rate.

Hereinafter, the component system of the steel sheet of the present invention will be described.

Carbon (C): 0.02 to 0.12 wt%

Carbon is an element which forms island martensite and has a great influence on grain size, fraction, etc. of the island martensite formed. Preferably, the microstructure of the steel of the present invention contains 5.57 to 8% of phase martensite. When the carbon content is less than 0.02% by weight, the fraction of the phase martensite is less than 5.57%, and the content of carbon is 0.12% by weight. When exceeding, the fraction of the island martensite exceeds 8%.

Silicon (Si): 0.01-0.6 wt%

Silicone is used as a deoxidizer and is a useful element for improving strength. This effect is insignificant when the content of silicon is less than 0.01% by weight. However, when it exceeds 0.6 weight%, low-temperature toughness and weldability will fall. Therefore, the content of the silicon is preferably limited to 0.01 to 0.6% by weight.

Manganese (Mn): 0.3-2.5 wt%

Manganese is an element that can improve the strength of steel by solid solution strengthening, and in order to exhibit such an effect in the present invention, it is preferable to contain 0.3 wt% or more. However, when it exceeds 2.5 weight%, hardenability may become high too much and the toughness of a weld part may fall large.

Aluminum (Al): 0.005 to 0.5 wt%

Aluminum is an element used as a deoxidizer of molten steel, and the solid solution of aluminum assists in the formation of phase martensite. In order to exhibit such an effect in the present invention, it is preferable to include 0.005% by weight or more. However, if it exceeds 0.5% by weight, nozzle clogging may occur during continuous casting.

Niobium (Nb): 0.005 to 0.1 wt%

Niobium is the most important element in the production of TMCP steel, and is an element that can be precipitated in the form of NbC or NbCN to greatly improve the strength of the base metal and the welded portion. In addition, niobium dissolved in reheating at a high temperature can suppress the recrystallization of austenite and suppress the transformation of ferrite or bainite to finely control the tissue. In addition, when slab is cooled after rough rolling, bainite may be formed even at a low cooling rate, and it may play a role of promoting phase martensite formation even at a low cooling rate by greatly increasing the stability of austenite during cooling after the final rolling. Can be. This effect is insignificant when the content of niobium is less than 0.005% by weight. On the other hand, when it exceeds 0.1% by weight, brittle cracks are caused at the corners of the steel.

Boron (B): 5-40 ppm

Boron is an element for improving hardenability and is an inexpensive element, and preferably 5 ppm or more in order to improve hardenability in the present invention. However, when it exceeds 40 ppm, Fe ₂₃ (CB) ₆ is formed, rather curability falls, and low-temperature toughness is also greatly reduced.

Titanium (Ti): 0.005 to 0.1 wt%

Titanium is an element that suppresses the growth of crystal grains upon reheating the slab and greatly improves low temperature toughness. In order to exhibit such an effect in the present invention, titanium is preferably included by 0.005% by weight or more. However, when it exceeds 0.1 weight%, nozzle clogging occurs at the time of performance, and low-temperature toughness falls.

Nitrogen (N): 15-150ppm

Nitrogen is an element that increases the strength of steel but decreases its toughness. When the nitrogen content is less than 15 ppm, the steelmaking load is increased. When the nitrogen content is more than 150 ppm, the toughness of the steel sheet is lowered.

The remainder of the present invention is iron (Fe). However, in the normal steel manufacturing process, impurities that are not intended from raw materials or the surrounding environment may be inevitably mixed, and thus cannot be excluded. Since these impurities are known to those skilled in the art of ordinary steel manufacturing, not all of them are specifically mentioned herein.

However, since phosphorus and sulfur are generally mentioned impurities, the following briefly describes them.

Phosphorus (P): 0.02 wt% or less

Phosphorus is an impurity contained inevitably and is contained in steel to lower toughness. Therefore, it is preferable to control phosphorus as low as possible. In theory, the phosphorus content is advantageously limited to 0%, but inevitably contained in the manufacturing process. Therefore, it is important to manage the upper limit, and in the present invention, the upper limit of the phosphorus content is preferably limited to 0.02% by weight.

Sulfur (S): 0.01 wt% or less

Sulfur is inevitable impurity, and reacts with manganese to form MnS, which lowers the low temperature toughness. In theory, the sulfur content is advantageously limited to 0%, but inevitably contained in the manufacturing process. Therefore, it is important to manage the upper limit, the upper limit of the sulfur content in the present invention is preferably limited to 0.01% by weight.

In addition, the steel material of the present invention is added when one or two or more elements of chromium (Cr), molybdenum (Mo), nickel (Ni), copper (Cu) and vanadium (V) to be described below additionally The effect can be further improved.

Chromium (Cr): 0.05-1.0 wt%

Chromium is an element that can increase the strength of steel by increasing the hardenability, and in order to exhibit such an effect in the present invention, it is preferably included 0.05% by weight or more. However, when it exceeds 1.0 weight%, weldability will fall.

Molybdenum (Mo): 0.01-1.0 wt%

Molybdenum is an element capable of greatly improving the hardenability, suppressing the formation of ferrite, and greatly improving the strength. In order to exhibit such an effect in the present invention, it is preferable to include 0.01 wt% or more. However, when it exceeds 1.0 weight%, the hardness of a weld part will be excessively increased and toughness will be inhibited.

Nickel (Ni): 0.01-2.0 wt%

Nickel is an element capable of improving the strength and toughness of the base material at the same time. In order to exhibit such an effect in the present invention, it is preferably included 0.01 wt% or more. However, when it exceeds 2.0 weight%, economic efficiency will fall.

Copper (Cu): 0.01-1.0 wt%

Copper is an element capable of minimizing toughness reduction of the base metal and at the same time improving strength, and in order to exhibit such an effect in the present invention, it is preferably included 0.01 wt% or more. However, when it exceeds 1.0 weight%, the quality of a product surface can be greatly reduced.

Vanadium (V): 0.005-0.3 wt%

Vanadium is a low solubility temperature compared to other alloying elements, is an element that can be deposited in the heat affected zone to prevent a drop in strength, in order to exhibit such an effect in the present invention is preferably included at least 0.005% by weight. Do. However, when it exceeds 0.3 weight%, the toughness of steel materials will fall.

As the steel sheet having the above-described component system, it is necessary to limit the microstructure of the steel sheet to preferable conditions for becoming a steel sheet excellent in fatigue crack growth suppression characteristics. The microstructure of the steel sheet includes 5.57-8% of phase martensite (MA), and the balance consists of a mixed structure of granular bainite and bainitic ferrite. Figure 1 schematically shows the microstructure of the steel sheet of the present invention, in which the martensite phase is distributed in the matrix structure so that the progression of the fatigue crack is blocked by the martensite phase so that the direction of fatigue crack change and the rate of crack growth decreases. Let's do it. This is because fatigue mars are refracted at the interface between the martensite phase and the matrix structure because the martensite structure is much stronger than the matrix structure. The grain size of the island martensite is preferably 5 μm or less. When the size of the island martensite grains exceeds 5 mu m, the grain size is too large and a weak boundary is formed in large quantities, resulting in inferior impact toughness. In addition, the fatigue crack growth rate decreases as the fraction of phase martensite in the present invention increases, but as shown in FIG. 2, the fraction of phase martensite that can be secured according to the cooling end temperature of the present invention is 5.57 to 8%. to be.

In addition, the fatigue crack propagation rate can be controlled to 2.5 * 10 ^-5 mm / cycle or less by the above-described component system and structure characteristics, manufacturing conditions described below, and can secure a tensile strength of 600MPa or more.

The most preferred method derived by the present inventors for producing the steel sheet which satisfies the object of the present invention as described above will be described below.

The manufacturing conditions of the steel sheet of the present invention consists of the re-heating, rough rolling, finishing rolling and cooling of the slab, the conditions of each step in the manufacturing method is controlled as follows.

Hereinafter, detailed conditions of each step will be described.

Slab reheating temperature: 1050 ~ 1250 ℃

The reheating temperature of the steel of the present invention is preferably at least 1050 ° C, in order to solidify the carbonitrides of titanium and niobium formed during casting. However, when reheating excessively high temperature, austenite may coarsen, so the reheating temperature is preferably 1250 ° C or lower.

Rough rolling: Tnr ~ 1250 ℃

The slab reheated as described above is subjected to rough rolling after heating to adjust its shape. The rolling temperature is at least the temperature Tnr at which recrystallization of austenite stops. By rolling, the casting structure such as dendrites formed during casting can be destroyed and the size of austenite can be reduced.

Finish rolling: Bs ~ Tnr

Finish rolling is performed by a method for introducing a nonuniform microstructure into an austenite structure of a roughly rolled steel sheet. The rolling temperature is preferably limited to the bainite transformation start temperature (Bs) or more than the austenite recrystallization temperature (Tnr).

Cooling condition after rolling: Cooling finish at 630 ~ 700 ℃ with cooling rate of 2 ~ 10 ℃ / s

The cooling condition of the present invention is one of the main features of the present invention, and the cooling is performed at a temperature of Bs temperature or higher at a cooling rate of 2 to 10 ° C./s, preferably water-cooling, thereby reducing the Bf temperature (the temperature at which the bainite transformation is terminated). Cooling) is terminated in the range of 630-700 degreeC or more). According to such cooling conditions, the microstructure of the steel can be produced with a 5.57-8% area fraction of the island martensite structure in the matrix. If the cooling end temperature exceeds 700 ℃ ferrite structure is formed, the strength is reduced and the martensite structure is difficult to form.

Hereinafter, the present invention will be described in detail by way of examples.

(Example)

The slab that satisfies the component system shown in Table 1 below was rolled and cooled to meet the manufacturing conditions shown in Table 2, and then the in-phase martensite (MA) fraction and crack growth rate were measured and shown in Table 3 below. 3 shows a microstructure photograph of Inventive Example 1. FIG.

division C Si Mn P S Al Ni Cu Cr Mo Ti Nb V B N Inventive Steel 1 0.03 0.25 1.56 0.012 0.002 0.017 0.27 0.12 0.32 0.07 0.016 0.05 0.04 6 35 Invention river 2 0.07 0.45 1.69 0.013 0.004 0.032 0.15 - 0.24 0.13 0.014 0.02 0.04 15 55 Invention steel 3 0.085 0.25 1.57 0.012 0.002 0.016 - - 0.22 0.2 0.022 0.04 - 5 42 Inventive Steel 4 0.12 0.35 1.42 0.013 0.002 0.013 0.25 0.22 0.1 0.32 0.013 0.03 - 8 42 Invention steel 5 0.075 0.25 1.52 0.013 0.004 0.015 - 0.24 0.32 0.04 0.02 0.05 - 15 42 Invention steel 6 0.082 0.35 1.43 0.012 0.003 0.013 - - 0.25 0.2 0.023 0.07 - 20 42 Invention steel 7 0.092 0.45 1.51 0.013 0.002 0.015 - - 0.19 0.15 0.03 0.04 - 16 42 Comparative River 1 0.004 0.25 1.52 0.014 0.004 0.034 - - - - 0.012 0.03 - 20 32 Comparative River 2 0.19 0.35 0.83 0.012 0.001 0.038 - - - - 0.014 0.04 - 24 28 Comparative Steel 3 0.07 0.45 1.22 0.013 0.005 0.024 - - - - 0.01 0.00 - 14 26 Comparative Steel 4 0.055 0.25 1.42 0.015 0.009 0.043 - - - - 0.009 0.04 - One 43

In Table 1, the content units of B and N are ppm, and the content units of elements other than this are in weight%.

The carbon content of Comparative Steel 1 is less than the carbon content limited by the present invention, and the Carbon content of Comparative Steel 2 exceeds the carbon content limited by the present invention. Comparative steel 3 does not contain niobium, and comparative steel 4 has a boron content less than the boron content of the present invention. On the contrary, inventive steels 1 to 7 are steel grades that satisfy all the component systems of the present invention.

Specimen Number Steel grade Slab
extraction
Temperature
(℃) Tnr
(℃) Crude rolling
End
Temperature
(℃) Bs
(℃) Sasang rolling begins
Temperature
(℃) Sasang rolling finish
Temperature
(℃) Cooling
speed
(℃) Cooling
End
Temperature
(℃) Inventory 1 Inventive Steel 1 1065 982 985 540 932 892 6.0 630 Inventive Example 2 Inventive Steel 1 1080 982 1000 540 912 872 5.0 670 Inventory 3 Inventive Steel 1 1120 982 1040 540 902 862 4.0 687 Comparative Example 1 Inventive Steel 1 1050 982 970 540 850 810 5.0 520 Honorable 4 Invention river 2 1070 843 990 524 793 753 6.0 655 Inventory 5 Invention river 2 1075 843 995 524 773 733 5.0 665 Inventory 6 Invention river 2 1110 843 1030 524 763 723 4.0 690 Comparative Example 2 Invention river 2 1060 843 980 524 850 810 5.0 515 Honorable 7 Invention steel 3 1080 1110 1000 531 1060 1020 6.0 635 Inventive Example 8 Invention steel 3 1070 1110 990 531 1040 1000 5.0 655 Proposition 9 Invention steel 3 1120 1110 1040 531 1030 990 4.0 678 Comparative Example 3 Invention steel 3 1055 1110 975 531 850 810 5.0 525 Inventory 10 Inventive Steel 4 1080 924 1000 532 874 834 6.0 645 Exhibit 11 Inventive Steel 4 1070 924 990 532 854 814 5.0 678 Inventory 12 Inventive Steel 4 1120 924 1040 532 844 804 4.0 699 Comparative Example 4 Inventive Steel 4 1055 924 975 532 850 810 5.0 545 Inventory 13 Invention steel 5 1080 967 1000 546 917 877 6.0 658 Inventory 14 Invention steel 5 1070 967 990 546 897 857 5.0 643 Honorable Mention 15 Invention steel 5 1120 967 1040 546 887 847 4.0 657 Comparative Example 5 Invention steel 5 1055 967 975 546 850 810 5.0 555 Inventory 16 Invention steel 6 1080 1099 1000 542 1049 1009 6.0 632 Inventory 17 Invention steel 6 1070 1099 990 542 999 959 5.0 678 Inventory 18 Invention steel 6 1120 1099 1040 542 1019 979 4.0 688 Comparative Example 6 Invention steel 6 1055 1099 975 542 850 810 5.0 535 Inventive Example 19 Invention steel 7 1080 946 1000 544 896 856 6.0 677 Inventory 20 Invention steel 7 1070 946 990 544 876 836 5.0 656 Inventory 21 Invention steel 7 1120 946 1040 544 866 826 4.0 688 Comparative Example 7 Invention steel 7 1055 946 975 544 850 810 5.0 512 Comparative Example 8 Comparative River 1 1080 923 1000 589 873 833 6.0 655 Comparative Example 9 Comparative River 1 1070 923 990 589 853 813 5.0 643 Comparative Example 10 Comparative River 1 1120 923 1040 589 843 803 4.0 635 Comparative Example 11 Comparative River 2 1080 1018 1000 604 968 928 6.0 679 Comparative Example 12 Comparative River 2 1070 1018 990 604 948 908 5.0 635 Comparative Example 13 Comparative River 2 1120 1018 1040 604 938 898 4.0 646 Comparative Example 14 Comparative Steel 3 1080 799 1000 700 749 709 6.0 633 Comparative Example 15 Comparative Steel 3 1070 799 990 700 729 689 5.0 666 Comparative Example 16 Comparative Steel 3 1120 799 1040 700 719 679 4.0 689 Comparative Example 17 Comparative Steel 4 1080 996 1000 583 946 906 6.0 672 Comparative Example 18 Comparative Steel 4 1070 996 990 583 926 886 5.0 695 Comparative Example 19 Comparative Steel 4 1120 996 1040 583 916 876 4.0 677

Specimen Number MA fraction (%) Crack Growth Rate Inventory 1 5.57 2.01 Inventive Example 2 6.81 1.57 Inventory 3 7.34 1.38 Comparative Example 1 2.16 3.22 Honorable 4 6.35 1.74 Inventory 5 6.66 1.63 Inventory 6 7.43 1.35 Comparative Example 2 2.01 3.28 Honorable 7 5.73 1.96 Inventive Example 8 6.35 1.74 Proposition 9 7.06 1.48 Comparative Example 3 2.16 3.22 Inventory 10 6.04 1.85 Exhibit 11 7.06 1.48 Inventory 12 7.71 1.25 Comparative Example 4 2.94 2.95 Inventory 13 6.44 1.7 Inventory 14 5.97 1.87 Honorable Mention 15 6.41 1.71 Comparative Example 5 3.25 2.84 Inventory 16 5.63 1.99 Inventory 17 7.06 1.48 Inventory 18 7.37 1.37 Comparative Example 6 2.63 3.06 Inventive Example 19 7.03 1.49 Inventory 20 6.38 1.72 Inventory 21 7.37 1.37 Comparative Example 7 1.90 3.31 Comparative Example 8 3.15 2.95 Comparative Example 9 2.95 3.01 Comparative Example 10 1.80 3.55 Comparative Example 11 2.55 3.03 Comparative Example 12 3.1 2.98 Comparative Example 13 1.5 3.90 Comparative Example 14 3.8 2.67 Comparative Example 15 2.3 3.35 Comparative Example 16 1.08 4.25 Comparative Example 17 2.09 3.67 Comparative Example 18 1.58 3.84 Comparative Example 19 0.99 4.35

In Table 3, the unit of crack propagation rate is 10 ⁻⁵ mm / cycle.

As shown in Table 2 and Table 3, Comparative Examples 1 to 7 is the end of the cooling is less than the limit of the present invention, the fraction of the island martensite is less than 5.57%, accordingly the crack growth rate was high. Comparative Examples 8 to 19 do not satisfy the component system of the present invention, the phase martensite fraction is less than 5.57%, the crack growth rate was high.

On the contrary, inventive examples 1 to 21 have a phase martensite fraction of 5.57% or more, and a crack propagation rate of 2.5 * 10 ^-5 mm / cycle or less, thereby ensuring excellent fatigue crack suppression characteristics and strength. . In addition, as shown in Figure 1, the matrix was a mixed structure of granular bainite and bainitic ferrite, it can be seen that the uniform martensite structure is uniformly distributed.

1 is a schematic diagram of a microstructure photograph of a steel sheet according to the present invention, in which fatigue crack propagation direction is changed by phase martensite.

2 is a graph showing the correlation between the fraction of phase martensite and the crack growth rate according to the cooling end temperature.

3 is a photograph of the microstructure of Inventive Example 1 observed with an electron microscope.

Claims (6)

By weight%, carbon (C): 0.02 to 0.12%, silicon (Si): 0.01 to 0.6%, manganese (Mn): 0.3 to 2.5%, aluminum (Al): 0.005 to 0.5%, niobium (Nb): 0.005 0.10%, boron (B): 5-40 ppm, titanium (Ti): 0.005-0.1%, nitrogen (N): 15-150 ppm, phosphorus (P): 0.02% or less, sulfur (S): 0.01% or less, Contains residual iron (Fe) and other unavoidable impurities, the microstructure comprises 5.57-8% of phase martensite (MA) and a mixed structure of residual granular bainite and bainitic ferrite, with a fatigue crack growth rate of 2.5 * High strength steel sheet with excellent fatigue crack propagation suppression property of 10 ^-5 mm / cycle or less. The method of claim 1, wherein the steel sheet is chromium (Cr): 0.05 ~ 1.0%, molybdenum (Mo): 0.01 ~ 1.0%, nickel (Ni): 0.01 ~ 2.0%, copper (Cu): 0.01 ~ 1.0% and vanadium (V): A high strength steel sheet having excellent fatigue crack propagation suppression characteristics, including one or two or more of 0.005 to 0.3%. The high strength steel sheet having excellent fatigue crack growth suppression characteristics according to claim 1, wherein the grain size of the island martensite is 5 µm or less. delete By weight%, carbon (C): 0.02 to 0.12%, silicon (Si): 0.01 to 0.6%, manganese (Mn): 0.3 to 2.5%, aluminum (Al): 0.005 to 0.5%, niobium (Nb): 0.005 0.10%, boron (B): 5-40 ppm, titanium (Ti): 0.005-0.1%, nitrogen (N): 15-150 ppm, phosphorus (P): 0.02% or less, sulfur (S): 0.01% or less, Reheating the slab comprising residual iron (Fe) and other unavoidable impurities at 1050-1250 ° C .; Roughly rolling the reheated slab at an austenite recrystallization temperature (Tnr) ˜1250 ° C .; Finishing the roughly rolled steel sheet in the range of bainite transformation start temperature (Bs) to Tnr; And A method of manufacturing a high strength steel sheet having excellent fatigue crack propagation suppression characteristics including a cooling step of cooling the finishing rolled steel sheet at 630 to 700 ° C. at a cooling rate of 2 to 10 ° C./s. The steel sheet is chromium (Cr): 0.05 ~ 1.0%, molybdenum (Mo): 0.01 ~ 1.0%, nickel (Ni): 0.01 ~ 2.0%, copper (Cu): 0.01 ~ 1.0% and vanadium (V): A method for producing a high strength steel sheet having excellent fatigue crack propagation suppression properties, including one or more of 0.005 to 0.3%.

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