鋼水經(jīng)盛鋼包注入鑄模凝固形成鋼錠。鋼液在煉鋼爐中冶煉完成后,必須鑄成一定形狀的錠或坯才能進(jìn)行加工。用鑄模鑄成鋼錠的工藝過(guò)程簡(jiǎn)稱(chēng)為鑄錠。
鋼錠至今仍是軋鋼生產(chǎn)的主要原料。鋼錠質(zhì)量的優(yōu)劣、錠型的狀況以及其重量大小對(duì)軋鋼生產(chǎn)有著十分重要的作用。在軋鋼生產(chǎn)中除各類(lèi)初軋機(jī)可選用鋼錠作原料外,一些特殊用途軋機(jī)、部分中厚板軋機(jī)也用鋼錠為原料,我國(guó)不少地方中小企業(yè)的開(kāi)坯機(jī)成品軋機(jī)也選用小鋼錠作原料。鋼錠選擇的內(nèi)容主要是正確地選擇鋼錠種類(lèi)、它的重量以及斷面形狀和尺寸大小。
鋼錠一般情況下大致可區(qū)分為以下幾類(lèi):
未凈鋼
鋼錠只經(jīng)過(guò)了基本(低限)的脫氧處理。鋼錠凝固時(shí),鋼錠模的四周及底部生成一層接近純鐵的金屬層,而碳、硫及磷等則于中央收縮孔附近生成偏折。金屬中的氧,會(huì)生成一氧化碳卷在金屬內(nèi)生成氣孔,但氣孔會(huì)在熱軋過(guò)程中消失。未凈鋼的優(yōu)點(diǎn)在于可獲得幾無(wú)缺陷的鋼材表面---表面幾為純鐵的緣故。絕大部份的未凈鋼含碳量均為小于0.1%的低碳鋼。
蓋帽鋼(加蓋鋼)
液中的氧使鋼錠的收縮中心附近的偏折情形,較未凈鋼為低,表面美觀,內(nèi)部化學(xué)成份均勻,機(jī)械性質(zhì)也較未凈鋼為佳。
全凈鋼
液中的氧早在凝固前便完全被脫除成限制在低限以?xún)?nèi)避免未凈鋼的邊緣效應(yīng)。脫氧處理,由在鋼液中添加鐵—硅合金使鋼液中的氧反產(chǎn)生成熔渣而得到均勻的金屬液。
半凈鋼
半凈鋼介于未凈鋼與全凈鋼之間,鋼液中經(jīng)加了少量的鐵——硅或鋁做為除氧劑,添加的量正好足夠去除未凈鋼的邊緣效應(yīng),使氧獲得充份的分解。
真空除氧鋼(真空除氣鋼)
藉由真空處理不需添加任何除氧元素,使鋼液得到充份的除氧效果且鋼中不生成非金屬介在物。處理過(guò)程是先增加鋼中的碳含量,然后將鋼液經(jīng)真空澆鑄,此時(shí)碳與氧將反應(yīng)生成一氧化碳而使鋼液中的碳與氧逐漸降至規(guī)定的水準(zhǔn)。由于過(guò)程中未添加會(huì)生成固態(tài)氧化物的除氧元素,鋼質(zhì)非常干凈。
鋼錠
除此之外,因澆鑄前鋼液中含氧量的不同,鋼錠分為鎮(zhèn)靜鋼、沸騰鋼和半鎮(zhèn)靜鋼三種基本類(lèi)型。
鎮(zhèn)靜鋼
又稱(chēng)全脫氧鋼,是凝固過(guò)程中鋼液內(nèi)氧含量低到不會(huì)與鋼中碳反應(yīng)生成一氧化碳?xì)馀莸匿?。鑄前鋼液須經(jīng)充分脫氧,如用硅和鋁脫氧,鋼中硅含量在0.3%左右,鋁含量在(0.02~0.06%)。鎮(zhèn)靜鋼錠均有縮孔,必須用帶保溫帽的錠模澆鑄。軋制后經(jīng)過(guò)切頭,鋼錠成坯率為85~89%。要求成分均勻、組織致密的鋼材采用這種鋼錠。鎮(zhèn)靜鋼采用上大下小帶保溫帽的鑄模。近年廣泛采用發(fā)熱保溫帽和隔熱板保溫帽等以提高成坯率。
沸騰鋼
鋼液中含氧量較高(0.02~0.04%)、在錠模中發(fā)生強(qiáng)烈碳氧反應(yīng)、生成一氧化碳?xì)馀?,使鋼液在模中沸騰而得名。這種鋼凝固一開(kāi)始,氣泡就形成并上浮。鋼錠表皮凝固成含鐵較純的殼層。當(dāng)表層達(dá)到所要求的厚度時(shí),在鋼錠頂部加上蓋板,使頂部凝固,阻止氣泡繼續(xù)逸出;也可在頂部加入硅鐵、鋁等脫氧進(jìn)行化學(xué)封頂;也有用瓶口式錠模進(jìn)行封頂。另一種方法是在鋼液凝固成表面層后即向整體鋼液中加鋁脫氧,這種鋼錠稱(chēng)為外沸內(nèi)鎮(zhèn)鋼。沸騰鋼一般采用上小下大敞開(kāi)式的瓶口式鑄模。沸騰鋼錠成坯率高達(dá)90~92%,主要用于低碳鋼。
半鎮(zhèn)靜鋼
介于鎮(zhèn)靜鋼和沸騰鋼之間的鋼種。這種鋼內(nèi)部氣體少,結(jié)構(gòu)接近于鎮(zhèn)靜鋼。半鎮(zhèn)靜鋼澆鑄初期不產(chǎn)生氣泡,當(dāng)頂部自然凝固封頂后(可采用瓶口模促進(jìn)封頂),由于鋼液中碳和氧的富集和溫度降低,促使在鋼錠頂部產(chǎn)生少量一氧化碳?xì)馀?,填充整個(gè)鋼液的凝固收縮空間。因此,可得到與沸騰鋼相近的鋼錠成坯率。半鎮(zhèn)靜鋼主要用于中等碳含量和中等質(zhì)量的結(jié)構(gòu)鋼,所用鑄模一般為敞開(kāi)式上小下大型。
脫模 澆鑄完畢的鋼錠,需待內(nèi)部完全凝固后方可脫模。對(duì)裂紋敏感性強(qiáng)的合金鋼錠,脫模后應(yīng)在熱狀態(tài)(>900℃)放入緩冷坑中保溫緩冷,或在不低于750℃溫度下熱送入軋鋼車(chē)間的均熱爐或加熱爐。
鍛圓廠家定制哪家好,就找唐山盛通鍛造有限公司。
The molten steel is injected into the mold through the ladle and solidified to form a steel ingot. After the molten steel is smelted in the steelmaking furnace, it must be cast into a certain shape of the ingot or billet for processing. The process of casting a steel ingot by a mold is simply referred to as an ingot.
Steel ingots are still the main raw material for rolling steel production. The quality of the ingot, the condition of the ingot type and its weight play a very important role in rolling steel production. In the steel rolling production, in addition to various types of roughing mills, steel ingots can be used as raw materials. Some special-purpose rolling mills and some medium-thick plate mills also use steel ingots as raw materials. In many local small and medium-sized enterprises, the mills for rolling mills also use small steel ingots as raw materials. . The selection of ingots is mainly to correctly select the type of ingot, its weight, and the shape and size of the section.
Steel ingots can generally be divided into the following categories:
Unclean steel
The ingots have only undergone the most basic (lower limit) deoxidation treatment. When the ingot is solidified, a layer of metal close to pure iron is formed around the bottom and bottom of the ingot mold, and carbon, sulfur and phosphorus are deflected near the central shrinkage hole. Oxygen in the metal creates a carbon monoxide roll that creates pores in the metal, but the pores disappear during the hot rolling process. The advantage of uncleaned steel is that it can obtain several flawless steel surfaces - the surface is pure iron. Most of the unpurified steel has a carbon content of less than 0.1%.
Cap steel (capped steel)
The oxygen in the liquid causes the deflection of the steel ingot near the center of shrinkage to be lower than that of the unpurified steel, the surface is beautiful, the internal chemical composition is uniform, and the mechanical properties are better than those of the unpurified steel.
Full net steel
The oxygen in the liquid is completely removed before it is solidified to be limited to the lower limit to avoid the edge effect of unclean steel. In the deoxidation treatment, an iron-silicon alloy is added to the molten steel to cause oxygen in the molten steel to be reversely generated into slag to obtain a uniform molten metal.
Semi-clean steel
Semi-clean steel is between unpurified steel and all-purified steel. A small amount of iron-silicon or aluminum is added as an oxygen scavenger in the molten steel. The amount added is just enough to remove the edge effect of unpurified steel and make oxygen. Get a full breakdown.
Vacuum deoxidized steel (vacuum degassing steel)
By vacuum treatment, it is not necessary to add any oxygen scavenging element, so that the molten steel can obtain a sufficient oxygen scavenging effect and no non-metal intervening material is formed in the steel. The treatment process is to first increase the carbon content in the steel, and then the molten steel is vacuum casted, at which time carbon and oxygen will react to form carbon monoxide to gradually reduce the carbon and oxygen in the molten steel to a prescribed level. The steel is very clean because no deoxidizing elements that form solid oxides are added during the process.
Steel ingot
In addition, due to the different oxygen content in the molten steel before casting, the steel ingot is divided into three basic types: killed steel, boiling steel and semi-killed steel.
Calm steel
Also known as fully deoxidized steel, it is a steel in which the oxygen content in the molten steel is low enough to not react with carbon in the steel to form carbon monoxide bubbles. The molten steel before casting must be fully deoxidized. For example, deoxidation with silicon and aluminum, the silicon content of the steel is about 0.3%, and the aluminum content is (0.02-0.06%). The calmed steel ingots have shrinkage holes and must be cast with an ingot with a heat insulating cap. After the rolling, the ingot is cut, and the ingot yield is 85 to 89%. Steel ingots are required for steels with uniform composition and compact structure. The killed steel is made of a mold with a large upper and lower insulation cap. In recent years, heat insulation caps and heat insulation board insulation caps have been widely used to increase the blanking rate.
Boiling steel
The molten steel has a high oxygen content (0.02-0.04%), and a strong carbon-oxygen reaction occurs in the ingot mold to generate carbon monoxide bubbles, which is named after the molten steel boils in the mold. At the beginning of this steel solidification, bubbles form and float. The steel ingot skin is solidified into a relatively pure shell layer containing iron. When the surface layer reaches the required thickness, a cover plate is added on the top of the ingot to solidify the top to prevent the bubbles from continuing to escape; or a de-oxygenation of ferrosilicon, aluminum or the like may be added at the top for chemical capping; Capping. Another method is to add aluminum to the whole molten steel after the solidification of the molten steel into a surface layer. This steel ingot is called an outer boiling inner steel. Boiling steel generally adopts a bottle opening mold with a small upper and a large open type. The boiling steel ingot has a blanking rate of 90-92%, which is mainly used for low carbon steel.
Semi-killed steel
A steel grade between calm steel and boiling steel. This steel has less internal gas and is structurally close to killed steel. In the initial stage of semi-killed steel casting, no bubbles are generated. When the top is naturally solidified and capped (the bottle die can be used to promote the capping), due to the enrichment of carbon and oxygen in the molten steel and the temperature decrease, a small amount of carbon monoxide bubbles are generated on the top of the ingot, filling the whole. The solidification shrinkage space of molten steel. Therefore, the billet ratio of the steel ingot similar to that of the boiling steel can be obtained. Semi-killed steel is mainly used for medium-carbon and medium-quality structural steels. The molds used are generally open, small, and large.
Demoulding The cast ingot must be demolded after the interior is completely solidified. For alloy ingots with strong crack sensitivity, after demolding, they should be placed in a slow cooling pit in a hot state (>900 °C) for slow cooling, or sent to a soaking furnace in a rolling mill at a temperature not lower than 750 °C or Heating furnace.
0315-3172368
熱線電話
關(guān)注官方賬號(hào)