2000MPa grade superhigh intensity high tenacity steel plate and manufacturing method thereof

Abstract

The invention provides a 2000MPa super high-strength and high-toughness steel sheet and a manufacturing method thereof. The 2000MPa super high-strength and high-toughness steel sheet comprises the following chemical components: 0.20 percent to 0.60 percent of C, 1.0 percent to 3.0 percent of Si, 1.0 percent to 5.0 percent of Mn, 0.10 percent to 0.60 percent of Mo, and the rest are Fe and inevitable impurities. In the invention, Mn-Si-Mo series components are adopted, and the steel sheet with bainite / martensite duplex phase as the tissue characteristic is obtained through a controlled rolling and cooling technology. The yield strength of the steel sheet is more than or equal to 1000Mpa, the tensile strength is more than or equal to 2000Mpa, the yield ratio is more than or equal to 0.75, the charpy impact power Akv (-40DEG C) is more than 50J, and the 50 percent ductile-brittle transition temperature FATT is lower than -40 DEG C.

Description

technical field

[0001] The invention relates to high-strength steel, in particular to a 2000MPa-level ultra-high-strength and high-toughness steel plate and a manufacturing method thereof. Background technique

[0002] Ultra-high-strength steel is a high-strength, high-toughness alloy steel developed on the basis of alloy structural steel. The thermal processing process is simple and the cost is relatively low. It has been widely used by aviation and aerospace departments. key material. Ultra-high-strength steels are more sensitive to hydrogen than normal-strength steels, and hydrogen-induced fractures may occur during use. Different microstructures have different sensitivities to hydrogen embrittlement, which generally increase in the following order: ferrite, pearlite, bainite, low carbon martensite, a mixture of martensite and bainite.

[0003] However, due to the low toughness of most ultra-high-strength steels, this will shorten their service life, making it a restric...

Examples

Embodiment 1

[0031] Smelt molten steel in a vacuum electromagnetic induction furnace according to the chemical composition shown in Table 1, and cast it into a continuous casting slab or steel ingot. The thickness of the continuous casting slab or steel ingot after casting is not less than 10 times the thickness of the finished steel plate. The steel ingot is heated to 1260°C and held for 120 minutes. The first stage of rolling is carried out on the thick plate rolling mill. The rolling temperature is 1150°C. Stage rolling, the deformation rate of the second stage rolling pass is 25%, the final rolling temperature is 1050°C, and the thickness of the finished steel plate is 18mm. After rolling, the steel plate is air-cooled.

Embodiment 2

[0033] The implementation method is the same as in Example 1, wherein the heating temperature is 1250°C, and the temperature is kept for 130 minutes; the rolling start temperature of the first stage is 1170°C, and the thickness of the rolled piece is 40mm; the rolling start temperature of the second stage rolling is 1150°C, and the pass deformation The ratio is 10%, the final rolling temperature is 1000°C, and the thickness of the finished steel plate is 18mm.

Embodiment 3

[0035] The implementation is the same as in Example 1, wherein the heating temperature is 1250°C, and the temperature is kept for 140 minutes; the rolling start temperature of the first stage is 1180°C, and the thickness of the rolled piece is 36mm; the rolling start temperature of the second stage rolling is 1100°C, and the pass deformation The ratio is 25%, the final rolling temperature is 1030°C, and the thickness of the finished steel plate is 12mm.

[0036]The scanning electron microscope photo (5000×) and the optical microscope photo (500×) of the microstructure of the 2000MPa class ultra-high strength and high toughness steel plate of this embodiment are shown in figure 1 and figure 2 .

technical field

[0001] The invention relates to high-strength steel, in particular to a 2000MPa-level ultra-high-strength and high-toughness steel plate and a manufacturing method thereof. Background technique

[0002] Ultra-high-strength steel is a high-strength, high-toughness alloy steel developed on the basis of alloy structural steel. The thermal processing process is simple and the cost is relatively low. It has been widely used by aviation and aerospace departments. key material. Ultra-high-strength steels are more sensitive to hydrogen than normal-strength steels, and hydrogen-induced fractures may occur during use. Different microstructures have different sensitivities to hydrogen embrittlement, which generally increase in the following order: ferrite, pearlite, bainite, low carbon martensite, a mixture of martensite and bainite.

[0003] However, due to the low toughness of most ultra-high-strength steels, this will shorten their service life, making it a restric...

Examples

Embodiment 1

[0031] Smelt molten steel in a vacuum electromagnetic induction furnace according to the chemical composition shown in Table 1, and cast it into a continuous casting slab or steel ingot. The thickness of the continuous casting slab or steel ingot after casting is not less than 10 times the thickness of the finished steel plate. The steel ingot is heated to 1260°C and held for 120 minutes. The first stage of rolling is carried out on the thick plate rolling mill. The rolling temperature is 1150°C. Stage rolling, the deformation rate of the second stage rolling pass is 25%, the final rolling temperature is 1050°C, and the thickness of the finished steel plate is 18mm. After rolling, the steel plate is air-cooled.

Embodiment 2

[0033] The implementation method is the same as in Example 1, wherein the heating temperature is 1250°C, and the temperature is kept for 130 minutes; the rolling start temperature of the first stage is 1170°C, and the thickness of the rolled piece is 40mm; the rolling start temperature of the second stage rolling is 1150°C, and the pass deformation The ratio is 10%, the final rolling temperature is 1000°C, and the thickness of the finished steel plate is 18mm.

Embodiment 3

[0035] The implementation is the same as in Example 1, wherein the heating temperature is 1250°C, and the temperature is kept for 140 minutes; the rolling start temperature of the first stage is 1180°C, and the thickness of the rolled piece is 36mm; the rolling start temperature of the second stage rolling is 1100°C, and the pass deformation The ratio is 25%, the final rolling temperature is 1030°C, and the thickness of the finished steel plate is 12mm.

[0036]The scanning electron microscope photo (5000×) and the optical microscope photo (500×) of the microstructure of the 2000MPa class ultra-high strength and high toughness steel plate of this embodiment are shown in figure 1 and figure 2 .

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