Wrought iron发表评论(0)编辑词条

Wrought iron is commercially pure iron. In contrast to steel, it has a very low carbon content. It is a fibrous material due to the slag inclusions (a normal constituent). This is also what gives it a "grain" resembling wood, which is visible when it is etched or bent to the point of failure. Wrought iron is tough, malleable, ductile and easily welded.

Before the development of effective methods of steelmaking and the availability of large quantities of steel, wrought iron was the most common form of malleable iron. A modest amount of wrought iron was used as a raw material for manufacturing of steel, which was mainly to produce swords, cutlery and other blades. Demand for wrought iron reached its peak in the 1860s with the adaptation of ironclad warships and railways, but then declined as mild steel became more available.

Items traditionally produced from wrought iron include rivets, nails, chains, railway couplings, water and steam pipes, nuts, bolts, horseshoes, handrails, straps for timber roof trusses, and ornamental ironwork.

Wrought iron is no longer produced on a commercial scale.[1] Many products described as wrought iron, such as guard rails and gates, are made of mild steel.[1] They retain that description because they were formerly made of wrought iron or have the appearance of wrought iron. True wrought iron is required for the authentic conservation of historic structures.

Terminology
Wrought iron is so named because it is worked from a bloom of porous iron mixed with slag and other impurities. The word "wrought" is an archaic past tense form of the verb to work. As irregular past-tense forms in English have historically fallen out of use over long periods of time, wrought became worked. Wrought iron literally means worked iron.

Wrought iron is a general term for the commodity, but is also used more specifically for finished iron goods, as manufactured by a blacksmith or other smith. It was used in this narrower sense in British Customs records, such manufactured iron being subject to a higher rate of duty than what might be called "unwrought" iron.

In the 17th, 18th and 19th centuries, wrought iron went by a wide variety of terms according to its form, origin, or quality.

Form
Bar iron — iron in bars, which are the usual product of the finery forge, but not necessarily made by that process. These might be square or flat, and flat bars might be narrow or broad.
Rod iron — cut from flat bar iron in a slitting mill to provide the raw material for nails.
Hoop iron — suitable for the hoops of barrels, apparently made by passing rod iron through flat rolls.
Plate iron — sheets of iron suitable for use as boiler plate.
Blackplate — sheets of iron, perhaps thinner than plate iron, from the black rolling stage of tinplate production.
Voyage iron — narrow flat bar iron, made or cut into bars of a particular weight, a commodity for sale in Africa for the Atlantic slave trade. The number of bars per ton gradually increased from 70 per ton in the 1660s to 75–80 per ton in 1685 and "near 92 to the ton" in 1731.[2]

History

Overview
Wrought iron has been used for many centuries, and is the "iron" that is referred to throughout western history. The other form of iron, cast iron, was not introduced into Western Europe until the 15th century; even then, due to its brittleness, it could only be used for a limited number of purposes. Throughout much of the Middle Ages iron was produced by the direct reduction of ore in manually operated bloomeries, although waterpower had begun to be employed by 1104.[9]

The raw material produced by all indirect processes is pig iron. It has a high carbon content and as a consequence it is brittle and could not be used to make hardware. The osmond process was the first of the indirect processes, developed by 1203, but bloomery production continued in many places. The process depended on the development of the blast furnace, of which medieval examples have been discovered at Lapphyttan, Sweden and in Germany.

The bloomery and osmond processes were gradually replaced from the 15th century by finery processes, of which there were two versions, the German and Walloon. They were in turn replaced from the late 18th century by puddling, with certain variants such as the Swedish Lancashire Process. These too are now obsolete, and wrought iron is no longer manufactured commercially, except one brand "Pure Iron" which is made for artist blacksmiths and restorations of older ironworks.[citation needed]

熟铁　　

    用生铁精炼而成的比较纯的铁.含碳量在0.02%以下,又叫锻铁.熟铁很软,延展性好,可以拉成丝,容易锻造和焊接.
　　一般含碳量小于0.02%的叫熟铁或纯铁，含量在0.02-2.11%的叫钢，含量在2.11-6.69%的叫生铁。熟铁软，塑性好，容易变形，强度和硬度均较低，用途不广；生铁含碳很多，硬而脆。
　　（Q235）属于普通碳素结构钢，一般用做建筑材料和不重要的机械结构材料，使用时一般部进行热处理。再说这种钢也不能热处理，低碳钢热处理性能不好。要是必须提高表面力学性能，要先进行表面渗碳，在进行表面淬火。
　　普通结构碳素钢，这类钢对化学成分要求不甚严格，碳、猛含量可在较大范围内变动，力学性能不太好。