78results about How to "Improve crack arrest performance" patented technology

This high-strength thick steel plate has a component composition in which the carbon equivalent (Ceq) is 0.3-0.5% and has a microstructure containing 70% or less of ferrite by area ratio and 30% or more of bainite by area ratio. At 1/4 of the plate thickness, the crystal grain boundary density, which is the total length per unit area of crystal grain boundaries having a crystal orientation difference of 15 DEG or greater, is 400-1000 mm/mm2; and the area ratio of the {100} plane, which forms an angle within 15 DEG with respect to a plane that is perpendicular to the main rolling direction, is 10-40%. At 1/2 of the plate thickness, the crystal grain boundary density is 300-900 mm/mm2; and the area ratio of the {110} plane, which forms an angle within 15 DEG with respect to a plane that is perpendicular to the main rolling direction, is 40-70%.

The invention relates to a high-strength thick steel plate with an excellent crack-arrest property. The steel plate has the following characteristics: a wide-plate tensile value Kca for determining the crack-arrest property is larger than 6000 N/mm<1.5>; yield strength at the positions, which are respectively 1/4 and 1/2 the thickness of the steel plate away from the surface of the steel plate, isno less than 460 MPa; tensile strength is 570 to 720 MPa; Charpy impact energy at minus 40 DEG C is no less than 200 J; and a zero-ductility transition temperature is less than minus 60 DEG C. The steel plate provided by the invention comprises the following components by weight: 0.04 to 0.16% of C, 0.1 to 0.5% of Si, 0.9 to 1.6% of Mn, 0.1 to 0.3% of Cu, 0.2 to 0.9% of Ni, no more than 0.02% ofP, no more than 0.02% of S, 0.01% to 0.05% of Als, 0.002 to 0.010% of N, 0.02% to 0.05% of Nb and 0.01 to 0.03% of Ti, with the balance being Fe and unavoidable impurities. According to the invention,through optimization of chemical components of a high-strength steel plate and adoption of controlled rolling and controlled cooling processes for controlling the microscopic structure and grain sizein a plate thickness direction, the crack-arrest steel plate with high yield and stable strength and toughness is obtained. The high-strength thick steel plate provided by the Invention is used as container vessel steel, and has the characteristics of excellent crack-arrest toughness, high yield strength, excellent low-temperature toughness and large thickness.

The present invention provides high strength thick steel plate superior in crack arrestability high in strength, free of deterioration of HAZ toughness, and free of anisotropy, that steel plate containing, by mass %, C: 0.03 to 0.15%, Si: 0.1 to 0.5%, Mn: 0.5 to 2.0%, P: ≦0.02%, S: ≦0.01%, Al: 0.001 to 0.1%, Ti: 0.005 to 0.02%, Ni: 0.15 to 2%, and N: 0.001 to 0.008% and having a balance of iron and unavoidable impurities as chemical components, having a microstructure of a ferrite and/or pearlite structure with bainite as a matrix phase, and having an average circle equivalent diameter of crystal grains with a crystal misorientation angle of 15° or more of 15 μm or less in the regions of 10% of plate thickness from the front and rear surfaces and of 40 μm or less in the other region including the center part of plate thickness.

The invention specifically relates to X80 pipeline steel with the high stress ratio and high arrest toughness and a preparation method and application of the X80 pipeline steel. The X80 pipeline steel is composed of, by weight, 0.03% to 0.08% of C, 0.15% to 0.35% of Si, 1.50% to 2.00% of Mn, not larger than 0.010% of P, not larger than 0.003% of S, 0.04% to 0.08% of Nb, 0.015% to 0.025% of Ti, 0.015% to 0.025% of Zr, not larger than 0.03% of Mo, not larger than 0.35% of Cu, not larger than 0.30% of Ni, not larger than 0.30% of Cr and the balance Fe and inevitable impurities. Zirconium is added to promote precipitation of proeutectoid ferrite, the banded structure level is reduced, and the stress ratio and the arrest toughness of a steel plate are effectively improved. The heating temperature is strictly controlled, and the recrystallization deformation temperature section in a rough rolling stage and the rolling reduction and the temperature of the last phase of rough rolling are reasonably matched, so that the austenite grain size is reduced to the maximum degree; and a rough-rolled intermediate billet is cooled, so that grain growth generated after recrystallization deformation is reduced.

The invention relates to a high-intensity, high-toughness and corrosion-resistant titanium alloy and a preparation method thereof, and belongs to the field of alloys. The titanium alloy is prepared from the following element components (in percentage by mass): 3.0 to 7.0 percent of Al; 2.0 to 6.0 percent of a beta-stable element (Mo+Nb+V), 0.01 to 6.0 percent of Ta, 0.5 to 3.5 percent of Zr and the balance of Ti and unavoidable impurities. The performance of the alloy is as follows: Rp0.2 is greater than or equal to 840 MPa, Rm is greater than or equal to 940 MPa, A is greater than or equal to8 percent, KIC is greater than or equal to 110 MPa.m<1/2>, KISCC is greater than or equal to 100 MPa.m<1/2>, and KV2 is greater than or equal to 60J. The alloy has good technology application and market prospects in the field of ship, marine engineering and the like.

The invention discloses a seawater corrosion resistant steel plate with high crack arrest and strain aging embrittlement resistance characteristics and a manufacturing method thereof. The seawater corrosion resistant steel plate is prepared from the compositions in percentage by weight: 0.040-0.070% of C, less than or equal to 0.15% of Si, 0.85-1.15% of Mn, less than or equal to 0.013% of P, lessthan or equal to 0.0030% of S, 0.90-1.20% of Cu, 0.60-1.00% of Ni, 0.05-0.30% of Mo, 0.010-0.030% of Nb, 0.008-0.014% of Ti, 0.040-0.070% of Al, less than or equal to 0.0050% of N, less than or equalto 0.0003% of B, 0.0010-0.0040% of Ca and the balance of Fe and inevitable impurities. The steel plate has high strength, excellent low-temperature toughness, the crack arresting characteristic and the strain aging embrittlement resistance characteristic, further has excellent seawater corrosion resistance, can withstand large heat input welding, is particularly suitable for icebreaker shells, offshore platforms, sea-crossing bridges, ocean wind tower structures, hydroelectric metal structures (pressure steel pipes, volutes, steel bifurcated pipes and hydraulic turbine metal components), pressure vessels and the like in ice sea areas, and can achieve stable mass industrial production.

The invention relates to low-roll-force gas-transmission pipeline steel which unit roll-force is lower than 18Kn/mm and a production method thereof. The pipeline steel comprises the following main components in percentage by weight: 96.3-98.6 wt% of Fe, 0.030-0.010 wt% of C, 1.20-1.90 wt% of Mn, 0.10-0.35 wt% of Si, 0.015-0.120 wt% of Nb, 0.005-0.025 wt% of Ti, 0.001-0.005 wt% of N and 0.020-0.040 wt% of Alt, wherein the Ti/N ratio is equal to 3-6, and the Ca/Alt ratio is greater than or equal to 0.10. The pipeline steel also comprises the following residual components in percentage by weight: at most 0.004 wt% of O, at most 0.010 wt% of P, at most 0.003 wt% of S, at most 0.03 wt% of As, at most 0.02 wt% of Sn and at most 0.02 wt% of Sb. A thick/medium plate rolling machine, of which the unit roll force is lower than 18 kN/mm, can be utilized to effectively roll various thin/medium/thick casting blanks to produce the gas-transmission pipeline steel with favorable anti-cracking performance in a ferrous metallurgy enterprise on a common equipment level by slightly adjusting the technique.

Disclosed is a production method of an X80 pipeline steel wide and thick plate. The thickness of the steel plate is larger than or equal to 19 mm, and the width of the steel plate is larger than or equal to 3800 mm. Steel comprises the chemical compositions of, by mass, 0.04-0.05% of C, no more than 0.10% of Si, 1.20-1.80% of Mn, no more than 0.015% of P, no more than 0.002% of S, 0.02-0.06% of Als, 0.02-0.08% of Nb, 0.010-0.025% of Ti, no more than 0.3% of Cr, no more than 0.3% of Mo, no more than 0.3% of Ni, no more than 0.3% of Cu, no more than 0.0005% of B, 0.001-0.002% of Ca, no less than0.3% of Cr+Mo, no more than 1.0% of Cu/Ni, no more than 0.20% of Pcm, and the balance Fe and inevitable impurities. The transverse and longitudinal microstructures of the steel plate are uniform, thetransverse and longitudinal full-thickness DWTT shearing areas at the temperature of minus 30 DEG C are all larger than or equal to 85%. The low-temperature drop weight crack arrest performance of the large-wall-thickness large-diameter high-steel-grade pipeline steel can be improved, and meanwhile the plate shape is easy to control during rolling.

The invention provides Cu-containing crack arrest steel and a preparation method thereof. The components of the Cu-containing crack arrest steel include 0.02-0.10% of C, 0.1-1% of Cu, 0.1-0.4% of Si, 0.5-1.2% of Mn, 0-0.2% of Al, 0.1-0.3% of Cr, 0.5-1.5% of Ni, 0-0.8% of Mo, 0.01-0.05% of Nb, 0.03-0.2% of Ti, 0-0.005% of S, 0-0.01% of P and the balance Fe and unavoidable impurity elements. The preparation method of the Cu-containing crack arrest steel includes the steps of smelting and hot rolling in which the rough rolling temperature is 1000-1100 DEG C, and the finishing rolling starting temperature is 800-1000 DEG C. A copper-rich nanophase is generated by designing a proper micro alloy content proportion, the phase composition in the steel and the shape thereof, especially separating-out of the copper-rich nanophase are controlled through the rolling and heat treatment technology, and therefore the strength, rigidity and crack arrest performance of the Cu-containing crack arrest steel are improved.

The invention discloses high-toughness quantitative-reduction ship plate marine steel. A steel plate comprises the following chemical components by weight percent: 0.04%-0.14% of C, 0.15%-0.45% of Si,0.90%-1.50% of Mn, less than or equal to 0.015% of P, less than or equal to 0.010% of S, 0.010%-0.040% of Nb, 0-0.20% of Cr, 0-0.030% of V, 0.005%-0.020% of Ti, 0.015%-0.050% of Als, less than or equal to 30 ppm of N, less than or equal to 30 ppm of O, less than or equal to 2 ppm of H, and the balance Fe and inevitable impurities, wherein Als is acid-soluble aluminum; a welding crack sensitivityindex (Pcm) of the steel plate is less than or equal to 0.22%; and a carbon equivalent value (CEV) is less than or equal to 0.39%. The steel plate is not liable to be broken and damaged, and has goodstrength and toughness, welding performance and crack arrest performance.

The invention discloses a method for rolling pipeline steel with large wall thickness, which includes the following process steps: (1) Heating: the continuous casting slab is heated by a walking beam heating furnace, and the preheating section is from room temperature at a rate of 4 to 5 min/ cm heating speed, the temperature is controlled at 800~900°C; the heating speed of the heating section is controlled at 6~8min/cm, the temperature is controlled at 1160~1180°C; the temperature of the soaking section is controlled at 1160±20°C, and the holding time is 120~160 minutes; (2) Rolling: rough rolling, finish rolling temperature ≥ 980 ℃, middle billet thickness range 80~90mm, adopt large reduction system at the same time, after widening, there are 2 consecutive passes with reduction rate ≥ 25%; finish rolling, start rolling The temperature is 830°C, the final rolling is 720~740°C, and the rolling is two passes; cooling, the starting cooling temperature is 690~710°C, the cooling speed is 15~18°C/S, and the final cooling is 380~420°C. A pipeline steel with a large wall thickness of 30.8mm, a pipe diameter of 1422mm, and a steel grade of X80 with excellent crack arrest performance was produced by using a billet with a cross-sectional size of 260mm×2280mm. Compared with the TMCP+OLT process, the manufacturing cost is reduced, that is, the online tempering cost is saved.

Low-cost X80 pipeline steel and a manufacturing method thereof are disclosed. The steel comprises following components by weight: 0.065-0.085% of C, 1.0-2.0% of Mn, 0.25-0.35% of Si, 0.10-0.25% of Cu, 0.10-0.30% of Ni, 0.10-0.50% of Cr, 0.02-0.04% of Nb, 0.005-0.03% of Ti, 0.02-0.04% of V, 0.02-0.06% of Alt, not more than 0.006% of Ca, not more than 0.015% of P, not more than 0.003% of S and not more than 0.012% of N, with the balance being Fe and trace unavoidable impurities. A hot rolling process is controlled as follows: a slab heating temperature is 1100-1200 DEG C, a recrystallization zone rolling temperature is 900-1150 DEG C, a non-recrystallization zone rolling temperature is 700-950 DEG C, a finish rolling temperature is 700-800 DEG C, a finish cooling temperature is 350-450 DEG C, and a cooling speed is 10-25 DEG C/s. Advantages and effects of the steel and the method are that: the adding amount of alloy elements is reduced, and the steel and the method have advantages of low cost, good production efficiency, good product comprehensive performance, and the like.

The present invention relates to pipeline steel, and is especially one kind of superhigh strength X100 pipeline steel and process of making hot rolled plate of the X100 pipeline steel. The superhigh strength X100 pipeline steel consists of C 0.015-0.080 wt%, Mn 1.80-2.50 wt%, Si not more than 0.6 wt%, S not more than 0.0030 wt%, P not more than 0.015 wt%, Nb 0.04-0.15 wt%, Ti 0.005-0.030 wt%, V not more than 0.120 wt%, Alt not more than 0.060 wt%, N not more than 0.010 wt%, O not more than 0.006 wt%, Mo 0.10-0.60 wt%, Cu not more than 0.50 wt%, Ni not more than 1.50 wt%, Cr not more than 1.0 wt%, B not more than 0.0020 wt%, Ca not more than 0.01 wt%, and Fe and inevitable impurity for the rest. The rolling process of making hot rolled plate has plate blank heating temperature of 1100-1250 deg.c, final rolling temperature of 720-880 deg.c, final cooling temperature of 200-500 deg.c and cooling speed of 3-30 deg.c/s.

The invention provides a segmental welding method for butt welding of raw material band steel joint plates of a high-frequency straight welding tube. The method comprises the following steps of: segmenting: dividing a welding segment and a non-welding segment according to the width of raw material belt steel; and welding: when the tail part of the last reel of raw material band steel is left after the raw material band steel is input on a welding tube production line, unreeling the next reel of raw material band steel and leading the head part of the next reel of raw material band steel, undercutting and shearing the head and the tail of the raw material band steel to be neat and aligned, and then welding the segmented welding segment, wherein the welding method of carbon dioxide gas arc welding or manual arc welding is adopted for the butt welding of the raw material band steel. The segmental welding method provided by the invention has the advantages that no welding seams or weldingflashes exist so that the phenomenon of surface scratch of a tube blank is not generated, the surface quality of a welded tube meet a standard requirement of a qualified welded tube, the first pass yield of the welded tube is improved, the service life of a roller is prolonged, continuous production can be maintained, no losses in operation time is ensured, the consumption of welding materials isdecreased by 1/3, meanwhile, partial electric consumption is lowered.

The invention relates to a method for arresting ductile fracture of natural gas pipelines of level X100 and above, wherein two or more fracture arresting steel pipes, which are relatively low in strength level but relatively high in wall thickness and toughness, are connected among X100 or higher-level steel pipes at intervals of 50-100 steel pipes and by a length within a range of 600-1200 m; and the wall thickness of the fracture arresting steel pipe is calculated according to pressure bearing capacity the same as that of a main pipeline, while the toughness thereof is determined by a method recommended in Petroleum and Natural Gas Industries-Steel Pipe for Pipeline Transport System ISO 3183: 2007 and the appendix G of Pipeline Steel Pipe Standards (Version 44) API Spec5L: 2007. The manufacturing technical difficulty and the manufacturing cost of the fracture arresting steel pipe with low strength level and high toughness are low, and the toughness index thereof is easy to achieve, so that the safety requirements of the pipeline fracture arrest are met, and unification of safety and economical efficiency is realized.

The invention discloses a thick-specification pipeline steel cooling method which is mainly used for cooling thick-specification pipeline steel with the thickness of more than 12.0mm subjected to heating, dephosphorization, rough rolling, head/tail flying shear cutting, dephosphorization and finish rolling. The method comprises the following steps: quick cooling, air cooling and laminar cooling. The method can further integrally enhance the toughness of the thick-specification pipeline steel.