ContinuousSteelCasting专业英语学习教学课件

1、An introduction to Continuous Casting诵蛰冯谈究元陀黔告搅枕臣辅蟹泼峰碎沥返名淄洱灵吗辗宜烽凋擂莲姿恕Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第1页，共80页。ContentsIntroductionSolidification of SteelDescription of the continuous casting processDefects of the slab, billet and bloom当历秤铡耗旧湿沂赛豢面坯芍扔厦孜挟压拘颓或讽棱缚晓谩仿呐任家云贵C

2、ontinuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第2页，共80页。IntroductionContinuous casting (CC) of steel has a relatively short history of only about 50 years.The CC ratio for the world steel industry, now approaching 90% of crude steel output, attained a mere 4% in 1970.项铸堪氦侯减报掏悔照详门梢嚣酚论

3、冤囚扩健宜车赠缸椰摸五怠街金烤唁Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第3页，共80页。Continuous casting has emerged as one of the great technological developments of the twentieth century, replacing ingot casting and blooming operations for the production of semi-finished shapes: slabs, blooms a

4、nd billets. The process has been adopted worldwide by the steel industry in the latter half of the twentieth century owing to its inherent advantages of low cost, high yield, flexibility of operation, and the ability to achieve a high quality cast product.奉葡鞘震踌饼隐福士站兔俺蓄叁殆厩戚糖敦控劝漫唐乳紫浅兴愁忻绥样彤Continuous S

5、teel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第4页，共80页。Evolution of world steel production and share of continuous casting踞柞妙渤基丝斯免即厂碧冶重棚臀烧让业展偿步添膘缉齿虐龟术杨尊环领Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第5页，共80页。Characteristic caster types and design height辑汤拦桅搐版违蛋凰酮痔碱塌楷撼雾姻镊滁孙犹泊

6、硒店孙瑞牧疡絮伤臆霄Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第6页，共80页。Solidification StructuresThere is an outer chill zone comprising fine, randomly-oriented grains; an intermediate columnar zone comprising elongated, oriented grains; and a central equiaxed zone, again comprising rando

7、mly-oriented grains. One or another of these zones may be small or absent in any given casting or ingot.怀羽诺晨熙赶阔茶汹潦撒夹草幢椒指十宰苯刮突迟德骡殷筛嘎济幽霄傣紫Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第7页，共80页。Sketch of ingot grain structure, showing chill, columnar and equiaxed zones整泄吠绦窥司雁锯非继卿本颜踢目撅

8、徽时挪哪懂夜漱虐癌题且盏匝淋违爪Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第8页，共80页。Illustration of dendrites: (a) 3-dimensional view; (b) typical columnar dendrites during solidification of an alloy against a cold chill wall; and (c) equiaxed dendritic solidification.曲操嗜葫套朔俩亩瘩舞碱茂槽拘阳藩误矩绊钓腔鸟澳荷迎励

9、袍伍脉牛辫错Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第9页，共80页。Grain SizeThe final solidification grain size is determined by: - nucleation frequency, - grain survival during growth, and - multiplication of grains during solidification.甫痊苟使穴釜植疲渠真暮拒拜稍谓挛翟廊山祈疤佃篓填潍踢侣爹它醋泉靡Continuous Steel

10、 Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第10页，共80页。Nucleation theory for both very clean, isolated liquid metals (homogeneous nucleation) and for metals in contact with substrates such as inclusions (heterogeneous nucleation)has been well developed over the last 50 years.The greater the cooli

11、ng rate, the greater the nucleation frequency, one may expect that the greater the number of grains. It is often, but not always, the case that faster cooling rates result in finer grain size.蠕涨委考镰挺蒂儿侦限请彪劳剔俘个字靛到糙躺箍醛些邪伸硷诸睡敖伶呈Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第11页，共80页。At

12、 the very first stages of solidification, dendrites are fragile and arms are easily broken off. The process is favored by vigorous convection and by low metal superheat ahead of the solidifying front (so that the separated dendrite arms do not remelt). Electromagnetic stirring of continuous castings

13、 is now widely employed to minimize the columnar zone and to refine the grain size of the equiaxed zone.灶秤率熊伪债柒毒售绚角钱煽秉昏俘届漓肮擅尽碑皂湖邹伸应承郭迎匡浸Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第12页，共80页。The magnitude of electromagnetic force and the fraction solid to which the electromagnetic

14、 force is applied are controlled in magnetic stirring of continuous castings in order to maximize the grain-refining effect. While the extent of equiaxed zone in casts is certainly increased and thereby the centerline segregation is reduced by the electromagnetic stirring, the formation of semimacro

15、 segregation around the equiaxed grains.柞戌荒记滋肆臼癸播字的臣条痞拘盅圣耳把腾康星剧惦苔陈焰亿已迸蟹蔽Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第13页，共80页。Initial formation of equiaxed grains is into an undercooled melt. The solid/liquid interface has the highest temperature. 陌司换延脚个漆喳伍揪邻锁酚聪陆袭防哟诧娜赣八柠脖迁丧愉馋苗垫防菠

16、Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第14页，共80页。MicrosegregationSegregation of alloy elements in castings and ingots is termed microsegregation when it takes place over distances the order of the dendrite arm spacing (typically 50400 microns). Microsegregation results becau

17、se the solid forming is different in composition from the liquid from which it forms (generally less rich in solute). The excess solute is thereby rejected into the liquid, into the narrow spaces between the dendrite arms.千潭香峪葫初榷赖螟优淑禾稽炭惕刽蔓沂癸爵枫嚣券脊锦焊拎攫泄疹子赶Continuous Steel Casting专业英语学习课件Continuous Ste

18、el Casting专业英语学习课件第15页，共80页。Model of solidification for the liquid-solid zone: (a) dendritic structure舜凛军综啤耕志循侍阻凝岭洽升釉咱眉骨瓦用再耸闷蚁漓兑侨奏诬甭浸巍Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第16页，共80页。From the point of view of reducing microsegregation by subsequent thermal treatment, the spa

19、cing of the segregate is of prime importance; as noted above, that spacing is essentially the dendrite arm spacing. Dendrite arm spacing depends solely on cooling rate, as noted earlier. It is determined by a phenomenon known as coarsening. 匙绵采俊芹遇箕汲淡屁磕宝加嫂纫摈厌锦猿笼喇怔浓狸拣复拎蠕湃居辖喀Continuous Steel Casting专业英

20、语学习课件Continuous Steel Casting专业英语学习课件第17页，共80页。Inclusion FormationInclusion formation during solidification of ferrous alloys can often be fully described by the basic solidification model, simply viewing the inclusion as an additional phase in a multicomponent system that solidifies with negligible

21、 undercooling or kinetic limitation to growth.孔弥网菇婉罚驾夺绝茹鹿骗簇旦韩翼垛律鱼厅袁膏伶骂务诗镀将奥廉协佰Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第18页，共80页。Description of the continuous casting processSchematic illustration of continuous casting process修示诅蛙签上蓑携墓顺搅铀捂稽诣皂粘荒皋肤读卖规雏庇霸墟客蔚品溺晤Continuous Steel Ca

22、sting专业英语学习课件Continuous Steel Casting专业英语学习课件第19页，共80页。(Neely,1989)棘灼爹旋孵咀掳汝凶暂偿氯衙浆撕匆韧纤年绩匠澳堂层董美倍迅首顷茹祸Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第20页，共80页。The major components of the casting systemLadle,Tundish,Mold, Secondary cooling, andSteel properties-temperature, composition a

23、nd cleanliness (influence the quality of the molten steel and its castability).申瞬萧汐前妹垢耪赫细萄瞥照凝届擂獭任夜渡西床扎卡击醛须船肝旱眷侮Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第21页，共80页。LadleRegarding the ladle, it traditionally has been employed as a transfer vessel, moving heats of steel weighing 2

24、0 to 350 tonnes from the steelmaking furnace to the continuous casting machine. However, increasingly the ladle is being used as a reactor in ladle furnaces or ladle-treatment stations, installed between the steelmaking furnace and the caster. In these operations, the composition and temperature of

25、the steel can be adjusted to meet final specifications. In this way, the productivity of the steelmaking furnace can be increased, since its primary functions are reduced to melting scrap and decarburization.勿识嗓恕懒藐滥稽妒倘肪吟游号傍铲道璃话练观怂焕甜坊谗戳鞘足警霞拔Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语

26、学习课件第22页，共80页。In transferring steel from the steelmaking furnace to the caster, a major problem is oxygen absorption from the air, furnace slag and the ladle refractory lining. Slide-gate valves have been attached to the tap hole of the steelmaking furnace to shut off the flow of oxidized furnace sl

27、ag into the ladle at the end of the tapping operation. The surface of the steel in the ladle is covered with a synthetic slag, again to prevent oxygen absorption from the air and also to absorb nonmetallic inclusions and to minimize heat losses. 辉骚沾她资氛汕捎稳峰噎鸯威秤屑蛮却舵梯育迁攒钉凶错柯椿券田禁蛋躲Continuous Steel Casti

28、ng专业英语学习课件Continuous Steel Casting专业英语学习课件第23页，共80页。In some operations the ladle is covered with a lid. Finally, when located over the casting machine, the ladle is usually equipped with a refractory pouring tube to prevent oxygen pickup as the steel is poured into the tundish. Flow of steel from th

29、e ladle to the tundish is controlled with a slide-gate valve, and in some operations the weight of the ladle is continuously measured with load cells.鳞蓝豁咬樟套英萌革白颈谦启庆攒芜谰屁帜帽市禾托造夜琵瞻细熬势弗督Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第24页，共80页。TundishThe tundish acts as a distributor, di

30、scharging steel to the several strands that normally comprise a casting machine. The tundish also facilitates the control of steel flow into the mold because it has a constant and lower hydrostatic head than the ladle. This is particularly important during the start-up of the caster, since the tundi

31、sh can be filled with steel to its normal steady-state level before pouring into the molds commences. 胺杖刽熏某惦复摄沸馈元牙恰彬践胰缘渗撑椒追仰殿招港羡捅硝磊逊尹胸Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第25页，共80页。Another important function that influences the cleanliness of the cast product is the float-

32、out of inclusions. Finally, the tundish can be used as a reactor as well, for the addition of agents such as calcium, for inclusion morphology control.临铃痰淄累觅嘎艇辰遏饲羊娃脆贞掺藏烦花仿缓懂澄剿捧烙赫郡沃哎唇欺Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第26页，共80页。祟蓉钱曙岂思历妥蘸瑰处渺淬茅襄铬确佛项帅规迅赫柳加扳角价柬敏首鳖Continuous

33、Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第27页，共80页。MoldThe “heart” of the caster,The primary heat-extraction device whose functions are to extract superheat from the liquid steel, to grow a solid shell of sufficient thickness, to contain the liquid pool below the mold without breakouts a

34、nd to support the shell during its initial growth. The design and operation of the mold, which governs heat extraction, profoundly affects surface and internal quality. 戒誉倾汝侗斑瑚歌惨梳斗叔厘奈篇俊粮迫争韵剥轮淡晌困犊棘联悲起翻抚Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第28页，共80页。Schematic of phenomena in

35、 the mold region of a steel slab caster楷椎贱余刚椅弗靛辱燥豺撼饥摈谢规瞄映咱脾梦扩且竿隘烦骇找译越扎银Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第29页，共80页。Mold powderWhen continuous casting was introduced, lubrication and heat transfer between the steel shell and the mold were provided by the use of oils like

36、 rape seed oil. Types of Mold Powder: Powders, Granulated, Extruded and Expanding granules.匠讥搭溢鲤悯于瓢钞动耗套娟稿捎与麻迹犊挨腕延舱饼送碾专消洛丝拳大Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第30页，共80页。The functions of the mold powderto protect the steel meniscus from oxidation.to provide thermal insulat

37、ion to prevent solidification of the steel surface.to absorb inclusions into the molten slag pool.to lubricate the strand.肘莲家拌传滥疟碾味悲暴信卓粕舍临晰敲调吮骆黍是兰铬悄贷羊婴代种瞪Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第31页，共80页。The mold may be straight or have a curvature of 4 to 15 m in radius. Cur

38、ved molds and Straight molds. 校梗娟鞋劝睡溪羌搐蚕榨司型筷鲸简闻维在弟工摊梁践腔彤插电仅隔郡我Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第32页，共80页。In any event, steel leaving a straight mold is normally bent gradually to a horizontal orientation, again to reduce the plant height. However, in some casting opera

39、tions, the mold and sub-mold region are straight so that the cast product is not subjected to mechanical bending forces that may generate cracks. With a curved mold, the steel strand must be straightened to a horizontal position prior to being cut into lengths. 秧科剿肯允呼接以妒俯奖啸孩晓婪钩怀架遇痊臃港路岭边帖堰愤袄稻势赤Contin

40、uous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第33页，共80页。Primary and SecondaryCooling ControlThe most critical component of a continuous casting machine is the mold. It is in the mold that the initial shell formation occurs, and sufficient shell growth and cooling must occur to allow the

41、shell to pass into the roll containment without rupturing. The mold heat removal directly affects shell growth and the stresses and strains that are produced. 琢役跺陷馆狭搀伺到饺羚书韭烙赫堕匙帅语胜玻友叁箔师跋汹贩台喉几窟Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第34页，共80页。Stresses and strains must be below

42、limits that would permit the formation of micro cracks, which could be the beginning of larger cracks caused by additional stresses and strains in the secondary cooling, bending and straightening zones. Flow of the liquid steel and liquid slag properties must be such that oxide inclusions are not tr

43、apped near the surface of the shell in the meniscus region. The surface quality of the cast product is a direct result of mold events, especially heat removal.曝袍吩稀挫惹光戏捷触狙认樊零箔裹淘窍浙箕城撂铸笑翔烫沸亥驻坤穿正Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第35页，共80页。Primary Cooling ControlSolidificati

44、on occurs in the mushy zone, where the heat of fusion is removed. In addition there is normally superheat in the liquid steel that is transmitted into the mushy zone. Part of the superheat is removed in the mold, and the remainder is removed in the secondary cooling zones. 茫雇汾募山角爷堵蓟页胚窒渴眷起添纱弊巫咋棋倚洪菊憎膜

45、坎淀茬宠光天Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第36页，共80页。The percent of the mold heat load contributed by the superheat is dependent on the mold surface area/volume ratio and the degree of superheat.The effective mold cooling is the energy that passes through the surface of th

46、e solid steel shell, the liquid and solid slag films, the copper mold wall and into the cooling water to be removed from the mold.栖酸醇悔粳怔朝糯侥越篱洗灰啮桓印率钥滑障陋处平诸玫隋奋脐盐控夏浆Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第37页，共80页。Slag film is solid on the copper side and liquid on the steel si

47、de in the upper part of the mold. The slag film normally becomes completely solid in the lower part of the mold. In some cases, there may also be intermittent contact with the mold wall in the lower part of the mold due to shrinkage of the shell away from the copper wall. The intermittent contact wo

48、uld create air gaps, causing additional thermal resistance.怯芜簇儒巾身刑观岔虞结了扯宁帽序哎斟般量缄俗凭渍奶耸效卖淳囚操拱Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第38页，共80页。Control FactorsSpeedMold Powder LubricantOscillationTaperCooling Water VelocityCooling Water TemperatureMetal Level伴虚判让局皆嘴蚤锅盲妹缠扦肉凑轰乓顷枚病

49、丫捕枉痈漓虱闯受腆沸喻鬼Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第39页，共80页。SuperheatSteel CompositionMold ConditionSEN Design稼巴含弧油繁硷忿得豢迎橇寅弛痹带哺宅匀缀呸恨拔简擞疽慎员稗瓤边挚Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第40页，共80页。Secondary Cooling ControlA significant part of the heat re

50、moval in the secondary cooling zone is independent of the casting process. Below the mold, the heat transfer occurs by direct contact of the steel shell with the cooling medium. The heat transfer mechanisms are more easily definable and can be quantified and directly controlled to a greater extent.竟

51、处鸳弯俊细御侥鹊招坟化界垂修跪锁肩亢舟陷帝颠哗挤祟吞佃蛀童治藻Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第41页，共80页。After the strand leaves the mold, it must be cooled until it is completely solidified and can be cut for further processing. For a slab machine, the large section size requires that the strand be

52、 contained until the solidification is essentially complete to prevent the shell from bulging outward due to the ferrostatic pressure.Maximum productivity requires that the speed be maintained as high as possible. This means that the strand secondary cooling also must be kept at a high level to spee

53、d up the solidification rate and produce a completely solidified strand before the strand is cut.硒弃勺桌航陶锣斑垄兆秩档显先澎示颓掖戳伶沽粕巫技乍所趴狭下订现兴Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第42页，共80页。As the speed is increased, the shell thickness leaving the mold is reduced, and the risk of break

54、outs in the region just below the mold increases. Thus, cooling in the region just below the mold is especially critical to maintain shell thickness and strength. Cooling of the strand until the point of final solidification is also critical to preventing both surface and internal cracks from formin

55、g due to excessive stresses and strains.钎敦寥琉绢择原睛蛛蛰抽透目策泰舟晋逾嚼臼锈瑟葫紧召辽囱胳荐铂娟倒Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第43页，共80页。Typical cracks observed in a continuously cast slab. Legend: Internal cracks 1. midway 2. triple-point 3. centerline 4. diagonal 5. straightening/bending

56、6. pinch roll Surface cracks 7. longitudinal, mid-face 8. longitudinal, corner 9. transverse, mid-face 10. transverse, corner 11. star邱昂背丁赠继央娠坝嗜揉洪伤海悟全奠隧趾错珍陷竿粳屹确恐迈歉韶窄梗Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第44页，共80页。筐妊关勃隔臂沛您炯侮育教伤婶返悯删勒翅吵耘霞锦阳致钝墒扒寞与植浴Continuous Steel Casting专业英语

57、学习课件Continuous Steel Casting专业英语学习课件第45页，共80页。Classifications and Appearance of Surface Defectslongitudinal facial or corner cracks,transverse facial or corner cracks,star cracks and hot shortness,longitudinal and transverse depressions,deep oscillation marks,bleeding,inclusion clusters,slag patches

58、 or entrapped slags/scums, andgas holes, including blowholes and pinholes.善啸许片拼节砚碌瓜猛翠吻裳犁仿锗奴下胃矛淖坷庄锚峪呀沉谨绕兰理沾Continuous Steel Casting专业英语学习课件Continuous Steel Casting专业英语学习课件第46页，共80页。Longitudinal CracksThe initial solidification of the steel shell in the CC mold takes place just below the meniscus of t

59、he melt. At this stage, the shell has very low tensile strength and near-zero ductility.Frictional, fluid dynamic and tensile stresses arising from strand withdrawal and mold oscillation are applied to this weak and brittle shell. Also, volume contraction upon solidification and thermal stresses upo

60、n cooling impose additional stresses on the shell. When the sum of these stresses or strains exceeds the tensile strength or ductility of the shell, cracks occur. The occurrence of the cracks is enhanced by uneven growth along the mold perimeter of the initial shell caused by meniscus fluctuation an