Abstract: Disclosed is a multilayered steel composite which compatibly achieves properties such as strength and ductility that are incompatible in conventional steels and is excellent in strength, ductility, weldability, toughness and fatigue strength. Also, disclosed is a method for producing the multilayered steel which is produced by rolling with least two kinds of steels having different chemical compositions and microstructure or different mechanical properties, in combination.

Abstract: Disclosed is a multilayered steel composite which compatibly achieves properties such as strength and ductility that are incompatible in conventional steels and is excellent in strength, ductility, weldability, toughness and fatigue strength. Also, disclosed is a method for producing the multilayered steel which is produced by rolling with least two kinds of steels having different chemical compositions and microstructure or different mechanical properties, in combination.

Abstract: A halogenated organic compound is introduced into a plasma. In the plasma state, substances are very reactive and chemical substances which are not readily decomposed such as halogenated organic compounds are decomposed in a short time. Specifically, in a high-temperature plasma exceeding 10,000.degree. C., almost all molecules are considered to dissociate into atoms. A reactive substance such as water is introduced into a plasma together with a halogenated organic compound. The decomposed halogenated organic compound is caused to react with the reactive substance, for preventing the decomposed organic compound from returning to its original state.

Abstract: A halogenated organic compound is introduced into a plasma. In the plasma state, substances are very reactive and chemical substances which are not readily decomposed such as halogenated organic compounds are decomposed in a short time. Specifically, in a high-temperature plasma exceeding 10,000.degree. C., almost all molecules are considered to dissociate into atoms. A reactive substance such as water is introduced into a plasma together with a halogenated organic compound. The decomposed halogenated organic compound is caused to react with the reactive substance, for preventing the decomposed organic compound from returning to its original state.

Abstract: A halogenated organic compound is introduced into a plasma. In the plasma state, substances are very reactive and chemical substances which are not readily decomposed such as halogenated organic compounds are decomposed in a short time. Specifically, in a high-temperature plasma exceeding 10,000.degree. C., almost all molecules are considered to dissociate into atoms. A reactive substance such as water is introduced into a plasma together with a halogenated organic compound. The decomposed halogenated organic compound is caused to react with the reactive substance, for preventing the decomposed organic compound from returning to its original state.

Abstract: A plasma reactor is developed on the fact that a high frequency plasma flame is larger in volume and lower in velocity and therefore a reaction material can stay therein for a relatively long period of time. The plasma reactor has a d.c. arc plasma torch provided in the upper part of the pipe which is an electrically insulative pipe high in heat-resistance and corrosion-resistance or is made up of electrically conductive components which are so designed as to prevent magnetic induction, a reaction material continuously introducing pipe opened in the vicinity of the arc plasma jet from the torch, and a high frequency coil wound around the firstly mentioned pipe coaxially with the torch.