![]() ![]() Like similar irons with the carbon formed into spherical or nodular shapes, malleable iron exhibits good ductility. Castability, heat treating and post-casting operations Creating malleable iron began in the United States in 1826 when Seth Boyden started a foundry for the production of harness hardware and other small castings. He discovered that iron castings which were too hard to be worked could be softened by packing them into iron ore or hammer slag and exposing them to high temperature for a number of days. RĂ©aumur conducted extensive research on malleable iron in 1720. Malleable iron is mentioned in England in a patent dating to the 1670s. By the Tang Dynasty, the use of malleable iron in China waned, although there are malleable iron artifacts dating to the 9th century. Malleable iron was used as early as the 4th century BCE, and archaeologists have found malleable iron artifacts made in China between 4th century BCE and 9th century CE. Three basic types of malleable iron are recognized within the casting industry: blackheart malleable iron, whiteheart malleable iron and pearlitic malleable iron. Carbon agglomerates into small roughly spherical aggregates of graphite, leaving a matrix of ferrite or pearlite according to the exact heat treatment used. Through an annealing heat treatment, the brittle structure as first cast is transformed into the malleable form. ![]() Malleable iron is cast as white iron, the structure being a metastable carbide in a pearlitic matrix. Polycrystalline structure of malleable iron at 100x magnification ![]()
0 Comments
Leave a Reply. |