Metallurgy of Stainless Steel and Cobalt – Chromium alloys

.  HISTORY OF STAINLESS STEEL     

 

Before Angle began his search for new materials orthodontists made use of noble metals and their alloys like Gold, Platinum, Iridium and silver alloys. Stainless steel was developed by Harry Brearly (1912) of Sheffield, F.MBecket of US, and Benno Strauss &Edward Maurer of Germany.  This steel was reported in the journal Stahl und Eisen in 1914 by Benno Strauss and Eduard Maurer and was first shown as a commercial product at the Malmö Exhibition in April of that year.

It entered Dentistry in 1919 being introduced at Krupp’s Dental Polyclinic in Germany by the company’s Dentist F. Hauptmeyer, where he used it to make prosthesis and called wipla (“Wie platin” in German means “like platinum”). It was introduced as an orthodontic wire in 1929 and Angle used it in his last year 1930 as ligature wire. By 1937 through the research work of P. Simon, R. Schwarz, G. Korkhaus, S. Friel, De Coster, A. Brusse, and J. Wunderly, the value of stainless steel as an orthodontic material had been confirmed.

 

HISTORY OF Co-Cr ALLOY

 

ELGILOY a particular form of Co-Cr alloy was developed by the ELGIN watch company for use in watch main springs. Their properties are very similar to that of stainless steel. They were simultaneously developed in the mid century. They introduced into orthodontics because these alloys can be drawn into wires and their properties are excellent for orthodontic purposes. The cobalt – chromium alloys are also used for partial denture construction one type is Vitallium (Co-Cr). In some earlier systems Nickel was used as a replacement for a certain % of cobalt. These alloys became known as ‘Haynes Stellites’ after Etwood Haynes who patented such an alloy for industrial uses in automobile manufacturing. Wiptam is another type of Co-Cr alloy used for fabrication the root portion of the post crown.

 

EXTRACTION OF IRON

 

The ores of iron are mainly Haematite, Magnetite, Limonite and siderite. Blast furnace is used for the primary reduction of iron ore to iron. It is either trapped off and solidified at the bottom of the furnace as pig iron or conveyed while in the molten state to other plants for steel making.

 

 

Steel is manufactured by

 

(a)          Bessemer Process

(b)         Open hearth process

(c)          Duplex process

(d)         Heroult electric arc furnace

(e)          Linz Donauwits process