The fine outside furnace is a steelworks the deepness to oxigenate to molten steel. Sulfur, main smelt craft is purify impurity and alloy are changed. LF fine steel includes different place erode medium to differ, main component is division of broken bits line and bath area. Because oxide is slaggy erode badly, steel wraps division of broken bits line to use the MgO-C brick of 12~18wt% normally, because slaggy line is fireproof material frit decrease is sharper, general in use process need changes broken bits line.
The fireproof material of bath area gets in fine process of steel fluid erode. Steel is packed broken bits needs before heat is repaired. The fireproof material of surface pouring broken bits basically is eroded by slaggy chemistry erode with physics. Magnalium material with carbon element can be used at the fireproof material of bath area. Aluminium magnesium material with carbon element or material of the aluminium magnesium that do not have carbon. In use process, what the wear-resisting material of bath area is located in steel to wrap is medium bottom, because this is very difficult,change. In the meantime, economy price is compared general and inferior. Accordingly, the service life of bath area decided the service life that whole steel packs greatly. The destruction of fireproof material mechanism is a more complex issue, slaggy property. Operate temperature. Be able to bear or endure the composition of material and metallurgy condition can affect his to erode a process, the attaint of spot steel liner is temperature field. Steel / the result that broken bits sheds field and chemistry to erode integrated coupling. Accordingly, the local injury mechanism of fireproof material has area of explore melt pool exploration, it is right not only fireproof the scientific exploration that erodes mechanism, and have stronger direct sense to project spot.
1. circumstance investigates some steelworks 180t to pack what pack with steel to tear open packet of process in converter steel in, discover steel packs bath bath brick ply of direction is apparent at 12 o'clock under all round bricky ply (1) seeing a picture, those who restricted the age that pack is farther rise, if express,1 is shown. Is the postulate of the factory: ? Stretch tight fine of F of blain fat Chang , scale 100% , manufacturing rolled steel is aluminous composed steel mostly, slag alkalinity is taller, if the watch is shown 2 times; The interior construction that steel includes basically distributings to was mixed at 5 o'clock at 7 o'clock (2) seeing a picture. When fine, electrode inserts steel in the bag, the position is.2 was nodded at 1 o'clock and at 6 o'clock the position (3) seeing a picture. The picture pursues 1: The ply of brick of the bath when tearing open a bag (Mm) is well-known, steel wraps the common position with bit weaker generation to have 3 kinds: ① stands by electrode. The high temperature that electrode produces can quicken slag / the reaction of steel fluid and fireproof material. ② is stood by breathe freely brick. Had blown breathe freely after the brick, quicken steel fluid to be opposite of fireproof material erode. ③ pours broken bits face. When steel packs have enough to meet need to end, the rest in needing teem to pack steel fluid and slag. In dump process, surface pouring broken bits is eroded by slag and steel fluid and erode. The weak part of the spot is not these 3 common shares, because this studies them,be significant. Of the fragile way that takes out bath from the spot and blame weakness direction hind brick (if pursue 4. The graph shows) 5 times, effective ply is 160mm and 60mm respectively. Can see from inside the graph, be not layer of broken bits of existence of surface of brick of weak direction bath, brick of weak direction bath does not have broken bits layer almost; Parallel at heating up extent direction, be not surface of brick of weak direction bath to have two break, in-house fill broken bits. Next, we will analyse resumptive brick, in order to decide attaint mechanism.
Graph 2: Steel is wrapped - breathe freely plan of bricky position site
Graph 3: Black lead electrode wraps medium opposite location drawing in steel
The brick after 2. is used undertakes method and process are apart from 25mm of hot side every other to cut a sample detect and analytic 1) to detect (25mm of × of 25)mm × 25mm) have physics and chemistry, the analysis heats up the microstructure of end. The physico-chemical analysis of the brick after 2) expresses the physical index of the 3 sample that gave out to be different from hot side. Can see, go up in these two direction in 0~25mm, the hole rate of bath brick and bulk density differ not quite, but summary prep above is not the bulk density of weak direction sample the bulk density of weak direction; 30~55mm interval, bulk density.80g/cm3 of sample of 2 weak direction. The hole of 2.74g/cm3.14.8% of brick of weak direction of blame of apparent prep above leads bulk density apparent under the blame of 16.2% fragile direction brick. Can say, the sample that comes from weak spot has higher bulk density and inferior hole rate in as same as hot side position, the bath brick that indicates direction of slight weak point is had inferior slaggy permeate layer or decarburized layer.
Different distance heats up a face the chemical index that the hole rate of sample piece and bulk basis leave hot side different to be apart from sample, can see side leaving heat is further, caO content drop off; Undertake comparative to the sample of same space, the weakness of prep above of content of sample CaO sample of direction of weakness of sample Central Africa chooses way; The sample of former brick layer; CaO content should be controlled in 1.3wt% , when blame weakness brick of direction was apart from hot side 30~55mm at 5 o'clock, caO content is 1.57% , be more than 1.3% , the osmosis of brick of this specification bath layer deepness is 25%mm at least. 3) microstructure analysis pursues the 6 microstructure graphs that are brick of the bath after direction was used at 5 o'clock. Can see, the ministry heating up a face of brick of the bath after direction was used at 5 o'clock shows cent to be 4 clearly, apparent branch is broken bits layer 4. . Reaction layer. Decarburized layer and permeate a layer; 3.4mm of ply of broken bits layer, reaction layer 2.7 ～ 4.6mm, 3.4mm of decarburized layer ply, the local oxidation calcic content that is far from hot end is higher also, the osmosis of this part deepness is very big.
From the watch the chemical analysis of 5 looks, all whole 25mm sample have slaggy permeate. The reaction layer of surface of directional bath brick is thicker at 5 o'clock, grain and matrix agglomeration are together, density is higher, intensity is higher, block up the farther oxidation of the oxide in oxygen and broken bits to the brick, it is certain to have fight erode function. Watch 5 gave out energy chart analysis, magnalium pointed spar is formed in reaction layer, the specification is in tall alkalinity broken bits, alumina and magnesia form pointed spar below high temperature is appearance of high temperature substance, can protect steel to wrap a brick well, avoid to be eroded further. Graph brick of the 6 bath after showing is in at 12 o'clock directional microstructure. Ply of broken bits layer is 0.6mm, the total ply of reaction layer and decarburized layer is 0.6mm about, permeate a ply to be 2.5mm about. At 5 o'clock unlike wall brick directional microstructure differs, weakness direction is broken bits layer. Reaction layer. Decarburized layer. Permeate a layer very thin, arrived at original bricky layer very quickly, this also with before watch 3 with the watch 4 medium physico-chemical analysises agree;
Watch 6 gave out the chemical composition of every part. Can see, as the addition that is apart from with hot side, the oxidation calcic content in the brick is reduced quickly. Area 5 when, oxidation calcic content already reached the chemical target of former brick layer, bricky osmosis deepness is relatively lesser. The place on put together is narrated, at 5 o'clock of direction hind bath brick has apparent reaction layer and decarburized layer, reaction layer is relatively compact and successive, but block up broken bits and oxygen erode with molten steel to be being destroyed of the brick further; After direction was used at 12 o'clock, bath brick surface cannot form stable reaction layer, contact ceaselessly with outside air or scoria. New reaction layer is swept very quickly, new decarburized layer reaction is exposed ceaselessly, this is one erode alternately - oxidation - erode / erode periodic. This also with a lot of document in about using hind the description that brick of broken bits line erodes is consistent.
The generation of compact reaction layer may be concerned with field work. Steel bag is pouring after steel, need from cast the rest of the teem on platform continuously steel bag broken bits and steel fluid. In process pouring broken bits, surface pouring broken bits is enclothed by broken bits, aggravate chemistry is eroded, but have heatproof concussion effect to the brick. In the meantime, tall alkalinity broken bits and brick form concentrated and successive reaction layer, block up air and broken bits are right of the brick erode further. At 12 o'clock direction irrigates the course that builds steel in, as the fall of surface of broken bits fluid, have one the layer is thin thin broken bits. Irrigate after building steel to finish, as a result of air oxidation and thermal shock, react compact layer cannot be formed. Be in below one round in use process, react the layer is swept by steel fluid, bring about reaction layer to be swept, the brick that causes this share finally has been eroded fast.
3. conclusion is aimed at steel of some steelworks fine to wrap bath brick local had eroded fast phenomenon, systems analysis area of steel bag bath is different of brick of the incomplete after place erode configuration, reach: of the following conclusion? of Bei of Zhuang of a legendary bird with poisonous feathers of benzene of duty bursa drips steel of fine of cowardly San F packs local melt to had injured fast main reason is to pour broken bits surface to be enclothed by slag, form compact reaction layer, of block up air and scoria erode further, raise what steel wraps a brick to fight erode function. Be not broken bits surface fireproof material is local and unusual erode, because the reaction layer between steel bag brick and scoria is not compact,basically be, the structure is inattentive, be eroded more easily in leaving smelt course one round to damage by molten steel. As the circular process that metallurgy fine works, the main mechanism that the lining that contain carbon injures is to erode - oxidation - erode / erode alternant process of the loop.
Be based on above analysis to conclude: ① rises be not broken bits face the packing of fireproof material, increase steel to wrap the reaction layer packing between brick and broken bits. The high temperature that ② raises fireproof material is fought lose strength, raise what steel wraps a brick to fight erode function. ③ rises be not broken bits surface of fireproof material fight oxidation ability, lower the resists unit process of cargo bandling of oxidation ability low metallurgy oxidation rate of fireproof material.
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