Surface hardening treatment device and surface hardening treatment method

Abstract

The present invention is provided with: an in-furnace atmosphere gas concentration detection device for detecting the hydrogen concentration or ammonia concentration in a treatment furnace; an in-furnace nitridation potential calculation device that calculates the nitridation potential in the processing furnace on the basis of the hydrogen concentration or ammonia concentration detected by the in-furnace atmosphere gas concentration detection device; and a gas introduction amount control device that, on the basis of the calculated nitriding potential in the processing furnace and the target nitriding potential, changes the introduction amount of each of the two or more types of furnace introduction gases other than the ammonia-decomposed gas while keeping the introduction amount of the ammonia-decomposed gas constant. Therefore, the nitridation potential in the processing furnace is close to the target nitridation potential.

Description

technical field [0001] The present invention relates to a surface-hardening treatment apparatus and a surface-hardening treatment method for performing surface-hardening treatment on a metal workpiece to be treated, such as nitriding, nitrocarburizing, and nitriding and quenching. Background technique [0002] There are many demands for nitriding treatment, which is a low-strain treatment, in the surface hardening treatment of a workpiece made of metals such as steel. As a method of nitriding treatment, a gas method, a salt bath method, a plasma method and the like are included. [0003] Among these methods, the gas method is comprehensively excellent in consideration of quality, environmental properties, mass productivity, and the like. By using the nitriding treatment by the gas method (gas nitriding treatment), strain caused by carburizing, carbonitriding, or induction hardening accompanying quenching of mechanical parts can be improved. As the same kind of treatment as...

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Problems solved by technology

However, Japanese Patent No. 5629436 (Patent Document 2) only discloses a specific example of the effective nitriding treatment of the first control (recorded in paragraphs 0096 and 0099 of Japanese Patent No. 5629436 (Patent Document 2): "In keeping NH 3 (Ammonia): N 2 (Nitrogen) = 80:20, by controlling the total amount of ammonia and nitrogen introduced into the treatment furnace, the nitriding potential can be controlled with good precision 3, 3), for which nitriding treatment or soft nitrogen There is no disclosure that the use of the second control is effective in the case of chemical processing, and there is no disclosure of specific examples of the effective second control.

[0010] In addition, in the method of controlling the total introduction amount while keeping the flow ratio of the gas introduced into the furnace constant, there is an advantage that the total amount of gas used can be expected to be suppressed. On the other hand, it is also known that the control range of the nitriding potential is narrow

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