A STUDY ON HYDROGEN AND NITROGEN IN STEEL IN THE COURSE OF STEEL-MANUFACTURING.
1937 Volume 23 Issue 10 Pages 954-962
Details
1937 Volume 23 Issue 10 Pages 954-962
The author studied the vacuum extraction process for the analysis of hydrogen only, and succeeded in finding a process, using a simple and compact furnace and large specimens. He also found that the selection of specimens is important. The analysis of hydrogen was made by this process, whilst the analysis proposed by the 19th Divisional Committee of the Institute for the Promotion of Science and Technology ("Gakujitsu Shinko-Kai") was applied to nitrogen. Thus, the variation of the contents of hydrogen and nitrogen in the course of steel-manufacturing was investigated, and the measures for reducing such elements were considered.
The results of the experiments are outlined below:-
(1) In the acid open hearth refining, more hydrogen exists in the melting-down period and it is reduced at the oxydizing stage, whilst at the latter half period there is again a tendency towards its increase and the quantity rapidly increases at the killing period and after discharge. Nitrogen reduces while the steel is boiling.
(2) In the basic open hearth furnace, the quantity of hydrogen increases even in the oxidizing and boiling periods, whilst that of nitrogen is considerably reduced by the boiling action.
(3) In the electric are furnace, the variation of hydrogen is not distinct, but it increases in the reducing period and after being discharged.
(4) In each meting process, the quantity of hydrogen before casting is generally 4·5-7·5cc/100g (0·0004-0·0007%).
(5) The main cause of mixing hydrogen is due to gas, water, etc, which are contained in steelmaking materials, slag-making agents combustion gas, air, ladle and moulds. The boiling action is very effective for the extermination of nitrogen, but is not remarkable for that of hydrogen.
(6) In ingots, more hydrogen and nitrogen exist at the top and bottom, but less at the middle.
The difference is more remarkable in nitrogen.
(7) The hydrogen in steel diffuses even at a normal temperature. In the range below 1, 000°C, it is quickest at a temperature immediately below the transformation point.
