金屬合金 外文翻譯 外文文獻 英文文獻 鐵類金屬

附錄5Ferrous Metals Metals are divided into two general groups: ferrous metals and nonferrous metals. Ferrous metals are those metals whose major element is iron. The major types of ferrous metals arc irons, carbon steels, alloy steels and tool steels. Iron The iron ore which we find in the earth is not pure. It contains some impurities which we must remove by smelting. The process of smelting consists of heating the ore in a blast furnace with coke and limestone, and reducing it to metal. Blasts of hot air enter the furnace from the bottom and provide the oxygen which is necessary for the reduction of the ore, The ore becomes mohen, and its oxide combines with carbon kom the coke. The non-metallic constituents of there combine with the limestone to form a liquid slag. This floats on top of the molten iron, and passes out of the furnace through a tap. The metal which remains is pig-iron, and consists of approximately 93 percent iron, 5 percent carbon, and 2 percent impurities. Remehing pig iron and scrap iron in a furnace to remove some of the impurities produces cast iron. The type, or grade, of cast iron is determined by the extent of refining, the amounts of pig iron and scrap iron, and the methods used to cast and cool the metal.The three primary types of cast iron are gray cast iron, white cast iron, and malleable iron.Gray cast iron is primarily used for cast frames, automobile engine blocks, handwheel, and east housings. White cast iron is hard and wear resistant and is used for parts such as train wheels. Malleable cast iron is a tough material used for tools such as pipes and wrenches. Generally, cast irons have very good compressive strength, corrosion resistance, and good machinability. The main disadvantage of cast iron is its natural brittleness. Carbon Steel Carbon steel is made from pig iron that has been refined and cleaned of most impurities. Most of the original carbon in the metal is burned out during the refining process. Measured amounts of carbon are then added to the molten metal to produce the exact grade of carbon steel desired. After the steel is poured into ingots and allowed to cool, it is usually sent to a rolling mill to be rolled and formed into specific shapes. The three principal types of carbon steel used in industry are low, medium, and high carbon steel. The percentage of carbon :is the most important factor in determining the mechanical properties of each type of carbon steel. : Low carbon contains between 0. 05% and O. 30% carbon and is primarily used for parts that do not require great strength. Typical uses of low carbon steel include chains, bolts, screws, washers, nuts, pins, wire, shafting, and pipes. This metal is also known as machine steel, mild steel, and cold-rolled steel. Low carbon steel is tough, ductile material that is easily machined and welded. It is useful for parts that must be stamped or formed. Containing between 0. 30 and 0.50% carbon, medium carbon steel is used for parts that required great strength than is possible with low carbon steel, such as gears, crankshafts, machine parts and axles. Because this steel has higher carbon content, it can be heat-treated to increase both hardness and wear resistance. Medium carbon steel is a tough, hardenable metal that has good machinability and is easily welded. Containing between 0.50 and 1.70% carbon, high carbon steel is used for parts that require hardness and strength, such as files, knives, drills, razors, and woodworking tools. Due to their increased carbon content, high carbon steels can be heat-treated to make them harder and more wear resistant than low or medium carbon steels. Due to their great hardness, high carbon steels are often brittle. Alloy Steels Alloy steels are basically carbon steels with elements added to modify of change the mechanical properties of the steel. All steels are alloy steels because each is a combination of elements, including carbon steel, a mixture of iron and carbon. To identify the two groups, one is called carbon or plain steel and the other is referred to as alloy steel. Alloying elements are added to the molten steel in measured amounts. The desired end product determines the elements and amounts added. The primary alloying elements and their effect on the steel are as follows: Boron The hardenability of an alloy is increased by boron. Only very small amounts of boron are needed to increase the hardenability characteristics of the other elements in the alloy. Chromium When used in small amount, chromium increases the depth hardness of the metal. The more chromium used, the better the alloy resists corrosion. Chromium is a principal element in stainless steels. Cobalt Cobalt is added to an alloy to increase wear resistance and increase red hardness, which is the ability of a metal to maintain a cutting edge at elevated temperature. Cobalt is a valuable addition to some high-speed tool steels. Lead By reducing the cutting friction, lead improves machinability. Leaded steels also have good weldability and formability. Manganese Impurities in alloy steels are controlled by using manganese as a purifier and scavenger. When added in larger amount ( 1 to 15 percent) , manganese produces good hardness and wear resistance. Molybdenum A tough alloy suitable for a wide range of high-strength applications, molybdenum steel permits good depth hardness and strength at elevated temperatures. Nickel High-strength alloys resistant to both elevated temperatures and corrosion are produced by nickel. When alloyed with molybdenum, nickel steel becomes a very tough alloy, which is often used for many aircraft parts. Larger amounts of nickel greatly add to the corrosion resistance of stainless steels. Phosphorus and Sulfur Free-machining carbon steels are produced with phosphorus and sulfur. When alloyed with carbon steels, phosphorus and suffer produce alloys with excellent machining characteristics. Tungsten When alloyed with steel, tungsten produces a variety of high-speed tool steels and adds hardenability and strength at elevated temperatures as well as high resistance to wear. Vanadium A tough, fine-grained steel that acts as a cleanser and purifier to eliminate many of the impurities of steel is produced by vanadium. Tool SteelsTool steels are a special grade of alloy steels used for making a wide variety of tools. Depending on their composition, tool steels are highly resistant to wear, shocks, and heat. These alloys gener ally contain more carbon, tungsten, and cobalt than do the standard alloy steels, i41 Another principal difference between most alloy steels and tool steels is the control with which elements are added.Tool steels are made with much closer quality controls than are other alloy steels.鐵類金屬金屬材料分為兩種類型：鐵類金屬和非鐵金屬。主要合金元素是貼的金屬材料是鐵類金屬。鐵類金屬主要有鐵、碳鋼、合金剛和工具鋼。鐵我們在地下找到的鐵礦石并不是純凈的，其中含有一些雜質(zhì)，必須通過冶煉去除。冶煉過程是把鐵礦石同焦炭合石灰石裝入高爐加溫，使他還原成金屬。熱風從高爐底部吹入高爐內(nèi)，供給鐵礦石進行氧化還原反應所需的氧氣。鐵礦石變成熔融狀態(tài)后，其氧化物便與焦炭中的碳化合。礦石里的非金屬成分與石灰石結(jié)合形成液態(tài)爐渣。爐渣浮在鐵液上面，經(jīng)過出渣口排出爐外。剩下的金屬就是生鐵，生鐵中含有約93%的鐵，5%的碳和2%的雜質(zhì)。將生鐵與廢鐵在爐子中重新融化，除去雜質(zhì)后得到鑄鐵。鑄鐵的類型和質(zhì)量等級決定于精煉程度、生鐵和廢鐵的比例，以及澆注方法和冷卻方式。鑄鐵主要分三種：灰鑄鐵、白口鑄鐵和可鍛鑄鐵。灰鑄鐵主要用于制造支架、汽車發(fā)動機氣缸、手輪和機架。白口鑄鐵硬度高、耐磨性好，可用于制造如火車車輪之類的零件?？慑戣T鐵是韌性較好，可用來制造如管道和扳手之類的零什。一般來說，鑄鐵有較好的抗壓強度，較好的耐腐蝕性能和良好的機械加工性能，其主要缺，：壬是脆性較大。 碳鋼 碳鋼是生鐵經(jīng)過精煉后除去大部分雜質(zhì)后得到的。由刁：生鐵中含有的碳在精煉過程中大部分被燒損，因此需要在金屬液中加入一定量的碳，以獲得所需等級的碳鋼。金屬液澆鑄到鑄型中并冷卻后，將其送人輥軋軋制成不同的形狀。 工業(yè)亡使用的碳鋼主要有三種：低碳鋼、中碳鋼和高碳鋼。碳含量是影響碳鋼力學性能的最重要因素。 低碳鋼碳含量為005030，主要用于制造強度要求刁；高的零件。低碳鋼主要用于制造鏈條、螺釘、螺桿、墊圈、螺母、銷釘、電線、秈和管道。低碳鋼又稱為結(jié)構(gòu)鋼、軟鋼和冷軋鋼。其韌性、延展性較好，易于切削加工和焊接，也有利于零伺：的卅，壓成形。 中碳鋼含碳量為030050，用于制造強度要求高于低碳鋼的零件，如齒輪、曲軸、機器零件和：乍軸。由于碳含量較高，可以對中碳鋼進行熱處理來提高其硬度和耐磨性。中碳鋼韌性較好，強度較高，機械加工性能和焊接性能好。 高碳鋼含碳量為050170，用于制造要求強度和硬度高的零件，如銼刀、鉆頭、剃刀和木工刀具。由于碳含量高，高碳鋼可以通過熱處理獲得比低碳鋼和中碳鋼更高的硬度和更好的耐磨性。由于其高硬度，高碳鋼通常也很脆。 合金鋼 合金鋼是在碳鋼中加入一定的合金元素以改變或提高其力學性能的鋼鐵材料。任意一種鋼鐵材料都含有一種以上的元素，因此，所有鋼鐵材料都是合金，其中包括普通碳鋼鐵和碳的合金。為了區(qū)分這兩類材料，一類稱為碳鋼或普通鋼，另類稱為合金鋼。 加入熔融鋼鐵中的合金元素是定量的。添加合金元素種類和數(shù)量決定于最終產(chǎn)品的性能要求。鋼鐵中主要合金元素以及它們的作用如下： 硼硼的加入可提高合金的淬透性。只需添加少量的硼元素就能提高合金中其他元素的淬透性。 鉻添加少量鉻元素能提高合金淬硬層深度。添加的鉻元素越多，合金的耐腐蝕性能越好。鉻是不銹鋼的主要合金元素。 鉆鉆用來提高合金的耐磨性和熱硬性。熱硬性指金屬在高溫下保持高硬度的能力。鈷是一些高速工具鋼中重要添加元素。 鉛鉛的加入可減少切削摩擦，提高切削加工性能。添加鉛的合金鋼可提高焊接性能和鍛造性能。 錳錳元素用來作凈化劑，控制合金中的雜質(zhì)含量。當合金中錳元素的含量在115之間時，合金具有較高的硬度和較好的耐磨性。 鉬含鉬鋼鐵合金具有良好的韌性、淬透性和熱強性，廣泛應用于強度要求高的場合。 鎳耐高溫和腐蝕的高強度合金是通過添加鎳元素生產(chǎn)出來的。添加了鉬元素的鎳合金鋼韌性很高，常用來制造航空器零件。不銹鋼中含有大量的鎳，極大地提高了合金的耐腐蝕性。磷和硫一易切削鋼中添加了磷和硫。碳鋼中的合金元素磷和硫能提高合金的切削加工性能。鎢在鋼中加入合金元素鎢，可獲得多種高速工具鋼。鎢能提高淬透性、熱硬性和耐磨性。釩釩可作為凈化劑去除鋼中的雜質(zhì)元素，獲得高韌性、晶粒尺寸細小的合金鋼。工具鋼合金工具鋼是用來制作各種工具的鋼。由于其成分特點，工具鋼具有高耐磨性、耐沖擊性和耐熱性。這種合金一般比普通合金含更多的碳。鎢和鈷。工具鋼與其他合金鋼的另一區(qū)別是對添加合金元素的控制。與其他合金相比，工具鋼生產(chǎn)的質(zhì)量控制要求更高。