Document 5DJ4zqXY7L2xRzGJ68mmaRD18

'! i i: i. n 1 t Compared to oilier steel-making nirlhixlx, tin- elec trie furnace h:is definite advamagrs. First. the electric arc is a .source ol ''pure ' heat. In which heating and melting of rile charge is accomplished without con taminating the melt In coitthustioti products of a gaseous or liquid fuel. Further, the rate of heat application is very rapid, yet can lie closely con trolled. The heat of the bath is easily adjustable, op or down, by adjusting the* electrical input to the electrodes. The conventional electric furnace, however, has one serious drawback. During the refining period, the bath of molten steel is comparatively quiet and circulation of the melt within the furnace is limited. Now it is common knowledge to mcltcrs of high-quality steels in electric-arc furnaces that an inert molten metai hath during the refilling period is undesirable. Alloy ing elements tend to stratify and temperature distribution is not uni form. Accurate sampling of the melt is thus practically impossible. Various manual or mechanical methods arc used in conventional furnaces to obtain some degree of mixing or stirring of the metal and slag. Occasional hand-stirring of the melt is difficult and cumbersome and the effects only temporary. The mtucliun slirrn has proved to be a practical and efficient method of setting up a continuous turbulence in the molten bath. This ingenious de vice was invented, and developed by ihe Allmiinna Svcnska Elcktriska AB, (ASEA), which is the largest elec trical works in Sweden. In simplest terms, the stirrer can be described as a segment of the stator of a gigantic induction motor which is mounted on the outside of the furnace bottom. It sets up a moving magnetic field which penetrates the non-magnetic steel furnace bottom as well as the refractory bottom lining. This mag netic field sets up mechanical forces which agitate and stir the entire bath. The result is a saving in time per melt, since the reaction between steel and slag is hastened. De-slagging is much more thorough since the slag can actually be swept toward the slag door by stirring action alone. In addi tion, the alloying elements which are added to the steel are much more rapidly and thoroughly distributed throughout the melt, and the temper ature of the bath is more uniform. Ail of this adds up to better chemical con trol which means better and more uniform stcei. The first installation of this type of stirrer was at the Surahammar steel works in Sweden in 1939. The second was at the Hagfors Works in 1947. The first Surahammar stirrer con firmed the principle, but had operat ing difficulties which required its be ing removed from service. In 1948, a second stirrer was installed at Sura hammar and is still operating success fully. Several additional stirrers have since been ordered for other Europe an steel plants and some are already in operation. During the latter part of 1950, an agreement to manufacture the stirrers in this country was made between Aros Electric, Incorporated, of New York and Elliott Company. Aros Electric, Incorporated, is a whollyowned subsidiary of ASEA and the induction stirrer is being marketed through this organization. The first Aros stirrer to be installed on an electric furnace in the United States (and the largest installed anywhere), went into service in the fall of 1952 at the melt shop ofTimken Roller Bear ing Company, Canton, Ohio. PAGE 8 iuwi;hf.\.x. sfiiing visa 1 ! <