A method for controlling inclusions in austenitic stainless steel for pressure vessels
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An austenitic stainless steel and pressure vessel technology, applied in the direction of improving process efficiency, can solve problems such as insufficient removal of inclusions, and achieve the effect of prolonging the floating removal time, reducing the quantity, and avoiding flaw detection.
Active Publication Date: 2020-08-25
SHANXI TAIGANG STAINLESS STEEL CO LTD
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Problems solved by technology
[0005] The technical problem to be solved by the present invention is: how to solve the problem of insufficient removal capacity of inclusions in the smelting process of austenitic stainless steel for pressure vessels
Method used
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Embodiment 1
[0010] Steel 316H
[0011] K-OBM-S is mixed with pretreated molten iron, the thickness of tapping slag is 30mm, and the amount of molten steel is 81.4t;
[0012] The vacuum degree is 1mbar during the boiling period of VOD, 1400kg of lime, 400kg of fluorite, 300kg of aluminum pellets are added during the reduction period, and the reduction time is 20min;
[0013] After LF enters the station to melt slag, add 50kg of aluminum powder to the slag surface, feed it into a pure calcium line of 160m, stir for 5min under the flow rate of argon gas blowing at the bottom of 2×150L / min, and then blow at the flow rate of argon gas at the bottom of 2×50L / min Stirring for 20 minutes, sedation time for 30 minutes;
[0014] In this embodiment, the CaO content in the lime is 95%, and the CaF in the fluorite 2 95% Al content, 99.6% Al content in aluminum pellets, 96.0% Al content in aluminum powder, 0.22kg / m of metallic calcium in pure calcium wire;
[0015] Refining slag system composition (...
Embodiment 2
[0020] Steel 316H
[0021] K-OBM-S is mixed with pretreated molten iron, the thickness of tapping slag is 30mm, and the amount of molten steel is 83.5t;
[0022] The vacuum degree is 1mbar during the boiling period of VOD, 1500kg of lime, 500kg of fluorite, 400kg of aluminum pellets are added during the reduction period, and the reduction time is 20min;
[0023] After the LF enters the station to melt slag, add 50kg of aluminum powder to the slag surface, feed it into a pure calcium line of 167m, stir for 5min at the flow rate of argon gas blowing at the bottom of 2×140L / min, and then blow at the flow rate of argon gas at the bottom of 2×45L / min Stirring for 25 minutes, sedation time for 35 minutes;
[0024] Lime CaO content is 95% in the present embodiment, and CaF in fluorite 2 95% Al content, 99.6% Al content in aluminum pellets, 96.0% Al content in aluminum powder, 0.22kg / m of metallic calcium in pure calcium wire;
[0025] In this embodiment, the refining slag is compo...
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Abstract
The invention relates to the field of stainless steel smelting, in particular to the field of smelting austenitic stainless steel for a pressure vessel. The invention relates to an inclusion control method of austenitic stainless steel for the pressure vessel. The method comprises the steps: adopting the process of a KOBMS furnace, a VOD furnace and an LF furnace during producing the austenitic stainless steel for the pressure vessel; when the thickness of slag in the KOBMS furnace is less than or equal to 50mm, tapping to the VOD furnace; in the boiling period of the VOD furnace, keeping thevacuum level no more than 2mbar; in the reducing period, adding 15-18kg of lime per ton steel, 3-6kg fluorite per ton steel and 4-5kg of aluminum pills per ton steel; keeping the reduction time for 15-25min, and then tapping to the LF furnace; after slugging by the LF furnace, adding0.625kg of aluminum powder per ton steel on top of the slag, and feeding 1-2m of pure calcium line per ton steel formicro calcium treatment; stirring for 5min under bottom blowing of 3.0-4.0L / min argon per ton steel, then stirring for 15-25min under bottom blowing of 1.0-1.5L / min argon per ton steel, and finally drawing a charge; and keeping continuous casting and killing time for 30-35min.
Description
technical field [0001] The invention relates to the field of stainless steel smelting, in particular to the field of austenitic stainless steel smelting for pressure vessels. Background technique [0002] The pressure vessel is an important part of some thermal power plants and nuclear reactors. Because it carries the key functions of equipment operation and energy conversion, it is required to be able to operate normally in harsh environments such as high temperature, high pressure, fluid erosion and corrosion. Some special fields It is also required that the design life of the pressure vessel is not less than 40 years and cannot be replaced. Stainless steel is one of the important materials for building pressure vessels, which puts forward higher requirements for stainless steel materials. [0003] Compared with ordinary stainless steel, stainless steel for pressure vessels has stricter requirements on steel purity, including five harmful elements, flaw detection, inclusi...
Claims
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