| 摘要 |
1,187,838. Refining steel. KONINKUJKE NEDERLANDSCHE HOOGOVENS EN STAALFABRIEKEN N.V. Aug.21, 1967 [Aug.23, 1966], No.38453/67. Addition to 1, 023, 505. Heading C7D. Rimmed steel is rendered non-ageing by annealing it in the form of an open coil in the presence of a nitrogen-binding substance such as milled steel, the latter being outside the coil and spaced from it, while a hydrogen containing gas is circulated through the coil and in contact with the nitrogen-building substance. The milled steel may be in the form of an open coil of sheet, or may be in the form of scrap; alternatively all or part of the inner wall of the furnace may be formed of milled steel or other material containing a nitrogenbinding substance such as aluminium. Preferably the gas is maintained at a pressure higher than atmospheric by withdrawing not more than 10% of the volume and replacing or augmenting the withdrawn gas by fresh gas. Use of a 25% nitrogen/ 75% hydrogen atmosphere is mentioned, while an atmosphere of 23% nitrogen/71% hydrogen/6% water vapour will simultaneously decarburise the steel. As exemplified and illustrated the process is carried out in a bell-type furnace. |
