Abstract: The hot rolling apparatus of the present invention has a mill arranged on the preceding stage, mills of a plurality of stands arranged on the later stage which are different-diameter roll mills including a pair of different-diameter work rolls having an equivalent roll diameter of less than 600 mm or minimum-diameter roll mills including a pair of work rolls having a diameter of less than 600 mm, and a cooling unit for cooling steel to be rolled which is arranged on each exit side of the mills of at least two stands on the later stage. The hot rolling apparatus can smoothly manufacture hot rolled plates of fine-particle steel.

Abstract: The hot rolling apparatus of the present invention has a mill arranged on the preceding stage, mills of a plurality of stands arranged on the later stage which are different-diameter roll mills including a pair of different-diameter work rolls having an equivalent roll diameter of less than 600 mm or minimum-diameter roll mills including a pair of work rolls having a diameter of less than 600 mm, and a cooling unit for cooling steel to be rolled which is arranged on each exit side of the mills of at least two stands on the later stage. The hot rolling apparatus can smoothly manufacture hot rolled plates of fine-particle steel.

Abstract: An additive for lubricating oils for diesel engines, comprising one or more kinds of amino alcohols which have one or more amino groups and one or more hydroxyl groups in a molecule and possess a function of dispersing water-containing calcium sulfate in oil, the hydroxyl groups being bound to the carbon atoms at the .beta.-positions to the amino groups; and a lubricating oil composition for diesel engines, which comprises the additives in an amount of from 0.1 to 10% by weight.

Abstract: The present invention relates to a hydrazinecarboxamide derivative of the general formula (I) shown below: ##STR1## wherein the substituents are as defined in the specification, which has a wide insecticidal spectrum at a low dosage, a process for producing said derivative, and utilization of said derivative as an insecticide.

Abstract: High chromium steels having extremely low carbon and nitrogen contents are produced by blowing more than 15 up to 40 Nl/min per ton of molten steel of an inert gas into a high chromium steel containing 0.8 to 2.5% of C and 10 to 35% of Cr in a ladle under a reduced pressure from bottom of a ladle and concurrently blowing oxygen gas to the molten steel surface to form 1 to 100 kg per ton of the molten steel of a slag containing not less than 20% of SiO.sub.2 and not more than 25% of Cr.sub.2 O.sub.3 at the end of oxygen blowing, terminating the oxygen blowing when the carbon concentration in the molten steel becomes not more than 0.020%, and subsequently blowing 6 to 40 Nl/min per ton of molten steel of an inert gas under a high vacuum of not more than 10 torr.

Abstract: An alloy steel having a high chromium content and an extremely low carbon content is produced by soft blowing oxygen gas under vacuum into a molten steel in a ladle containing a high chromium content and a high carbon content while blowing an inert gas of a flowing rate of 1-15 Nl/min per ton of the molten steel into the molten steel until the carbon content in the molten steel becomes 0.025-0.050% by weight. And subsequently only the blowing of the inert gas is conducted into the molten steel under a high vacuum degree of less than 10 torr so that the reaction active area ratio becomes more than 7% to reduce the carbon content in the steel to less than 0.003%.

Abstract: A method of denitriding a high chromium molten steel with a minimum chromium loss is disclosed. A high chromium molten steel containing 0.8-2.5% of C and 10-35% of Cr is denitrided to a final nitrogen content of not more than 40 ppm in a ladle under vacuum by flowing an inert gas into molten steel at a flow rate of not less than 15 Nl/min per ton of molten steel and at the same time blowing oxygen gas against molten steel until carbon content [C] in molten steel satisfies the following equations (1) and (2) in accordance with the carbon content prior to decarburization [C] of molten steel:[C].ltoreq.[C] 0.3, when 0.8.ltoreq.[C].ltoreq.1.0% (1)[c].ltoreq.55/70[c]--6/70, when 1.0.ltoreq.[C].ltoreq.2.5% (2).

Abstract: A method of producing alloy steels having an extremely low carbon content of not higher than 30 ppm is disclosed. The alloy steels can be obtained by vacuum treating a preliminarily decarburized molten steel in the presence of a proper amount of a slag containing specifically limited amounts of chromic oxide and silicon oxide under an inert gas atmosphere by means of a commonly used degassing apparatus.