37results about How to "Avoid Nitrogen Problems" patented technology

The invention relates to steel capable of being subjected to rapid impact molding for a cell shell and a preparation method thereof. The steel comprises the components in percentage by weight: 0.0001-0.0050% of C, 0.10-0.20% of Mn, 0.010-0.050% of Al, 0.0001-0.0040% of N, 0.010-0.030% of Nb, not more than 0.020% of P, not more than 0.015% of S, not more than 0.05% of Cu, not more than 0.05% of Ni, not more than 0.08% of Cr, not more than 0.05% of Mo and not more than 0.020% of Si. The preparation method comprises the steps: smelting according to a pure steel process and carrying out continuous casting to obtain a blank; heating the continuous cast blank; carrying out rough rolling; carrying out finish rolling in a single-phase austenite region; coiling; pickling; carrying out cold rolling; degreasing; annealing in a full-hydrogen bell-type furnace; and leveling for later use. The finished product obtained in the invention has stable mechanical properties, hardness being 90-100, tensile strength being not lower than 300 MPa, elongation percentage being not lower than 36% and yield ratio being not more than 0.6; the impact-molded cell shell is not easy to crack and has good drum body shape fixity; and the finished product has high corrosion resistance.

The invention discloses a preparation process of slag-stopping wire-feeding low-carbon aluminum killed clean steel, belonging to the technical field of ferrous metallurgy. The preparation process is characterized in that the production of the formed low-carbon aluminum killed clean steel is carried out without calcium treatment, and comprises the following steps of: adjusting 0.02-0.04% of refinedincoming molten steel [ Al ] in an LF (ladle furnace) refining step, wherein the temperature of the molten steel is not less than 1550 DEG C; adding lime according to 6-7 Kg / ton, controlling the slagcomposition, wherein the alkalinity CaO / SiO2 value is 8-9; refining to prepare white slag; adjusting the aluminum component of the molten steel, adding aluminum twice, and feeding a limestone cored wire; and controlling the mass percent of the refined outgoing molten steel component. Compared with the prior art, the preparation process has the advantages that a calcium treatment process is not adopted, the calcium treatment cost is saved, the problem that high-melting-point aluminate is easy to generate flocculation flow is avoided, the forming performance of a steel plate is improved, and the cold bending cracking occurrence probability is reduced.

The invention discloses a process for low-carbon silicon-controlled aluminum killed clean steel and belongs to the field of steel preparation. The production process comprises the following steps: (1)reducing the sulfur content of molten iron to 0.02% or below by means of molten iron pretreatment and the like; (2) an oxygen top-bottom combined blown converter is adopted, specifically, slag stop and tapping are carried out, and the end-point molten steel [O] of the converter is less than 600 ppm; (3) LF refining is carried out, specifically, the slag is controlled to comprise 55-60% of CaO, 35-40% of Al2O3, 2-4% of SiO2 and 5-7% of MgO, specifically, the alkalinity value of CaO / SiO2 is 20-26, refining is carried out to make white slag, the aluminum component of the molten steel is adjusted, and aluminum is dosed twice; (4) soft blowing and calming argon at the bottom of a steel ladle; (5) continuous casting is carried out; and (6) rolling steel. Compared with the prior art, the methodhas the advantages that the calcium treatment cost is saved, the problems that high-melting point aluminate is prone to flocculation and nitrogen increase are avoided, the forming performance of a steel plate is improved, and the occurrence probability of cold bending cracking is reduced.

The invention discloses a low-cost manufacturing method of a flaw-detection-ensured Q345B stage steel plate. The steel plate comprises, by mass percent, 0.15 to 0.20% of C, 0.15 to 0.50% of Si, 0.50 to 0.90% of Mn, not larger than 0.035% of P, not larger than 0.025% of S, 0.020 to 0.060% of Ti, 0.015 to 0.035% of Als, and the balance Fe and inevitable impurities. During preparing, molten iron is subject to KR desulfurization treatment firstly, the molten iron obtained after desulfurization treatment is subject to slag removal, the molten iron is converted into a converter to be smelted, outputmolten steel is subject to continuous casting and rolling, finally, the rolled steel plate is subject to stacking for slow-cooling for 24 to 72 hours, and then sampling inspection is carried out; thechemical components and the production process of the prepared Q345B stage steel plate are simple, the production cost is low, the flaw detection property is good, and the method has the good application and popularization prospects.

The invention relates to a smelting method of low-carbon low-nitrogen high-chrome steel. The low-carbon low-nitrogen high-chrome steel comprises the following components in mass percent: less than 0.03% of C, equal to or less than 0.10% of Si, equal to or less than 0.20% of Mn, 3.0-3.55% of Cr, less than 0.05% of N, equal to or less than 0.020% of P, equal to or less than 0.020% of S, and the balance of Fe and unavoidable impurities. The smelting method of low-carbon low-nitrogen high-chrome steel comprises the following steps: molten iron is pretreated; the pretreated molten iron is boiled in a converter and steel tapping is carried out, during the steel tapping, C is controlled to be between 0.03-0.05%, the temperature is higher than 1710 DEG C, and the oxygen activity in steel in a tank is ensured to be between 500-700 ppm; if the oxygen activity in steel is greater than 700 ppm, the oxygen activity of molten steel in the tank is controlled to be between 500-700 ppm; steel ladles are carried back to the converter after being carried out of an RH furnace, after the large tank is moved to a steel tapping position, argon blowing is carried out, low-carbon chromium iron is fed in the tank through a stock bin at the same time, and argon blowing is carried out for 5 minutes and then stopped; temperature is measured after the steel ladles are fed in an LF furnace, if the temperature is higher than 1575 DEG C, the steel ladles are fed in a machine for pouring, and if the temperature is lower than 1575 DEG C, the steel ladles are moved out after the temperature is raised to 1575 DEG C. The smelting method of low-carbon low-nitrogen high-chrome steel has the advantages of realizing the purpose that low-carbon low-nitrogen high-chrome steel is produced in a plain carbon steel factory and ensuring the reliability of RH production.

The invention belongs to the technical field of ferrous metallurgy, in particular relates to a method for controlling nitrogen content of aluminum killed steel produced in a converter process, and is used for preventing the problem that the nitrogen content increases in the aluminum killed steel produced in the converter process. The technical problem is solved by controlling the nitrogen content of the aluminum killed steel produced in the converter process according to the technical proposal as follows: the alkalinity of converter slag CaO / SiO2 is adjusted to 5-7 when a converter starts to produce the slag, the denitrification rate can be increased in the converter smelting process by controlling the alkalinity of the converter slag, the denitrification rate is increased from 50%-70% to 65%-85%, and the terminal nitrogen content of the molten steel in the converter can be controlled within 15PPm. The alkalinity is controlled, special slag is added, and a seal washer with brim is employed to seal between a steel ladle lower opening and a protection tube before starting continuous casting, thus realizing the stable control that the casting blank nitrogen content is not more than 35PPm by an LD-LF-SCC process and the casting blank nitrogen content is not more than 30PPm by an LD-LF-RH-BCC process.