Jfe Steel Corporation

Naho Inoue

Shinji Otsuka

Nobuyuki Ishikawa

Daisuke Mizuno

A method for evaluating a delayed fracture characteristic of a metal material that performs a step including a step (A) and a step (B) below once or a plurality of times to evaluate the delayed fracture characteristic of the metal material having been processed. Step (A): a step that brings an aqueous solution which includes a chloride ion into contact with a surface of the metal material to cause chloride of 1000 to 100000 mg/min chloride amount to deposit to the surface. Step (B): a step in which the metal material to which the chloride has deposited in the step (A) is left stationary in an air atmosphere at a temperature from −50 to 10° C. and at a relative humidity higher than or equal to a deliquescence humidity of the chloride.

Method for evaluating delayed fracture of metal material

A method for evaluating the delayed fracture characteristics of a metal material. The method including placing a solution-retaining material impregnated with a solution containing a chloride and having a pH of 3.5 or more on an edge face of the metal material, and maintaining a state in which the solution-retaining material is held at a deliquescence humidity of the chloride to thereby corrode the edge face.

A method for evaluating the delayed fracture characteristics of a metal material. The method including placing a solution-retaining material impregnated with a solution containing a chloride and having a pH of 3.5 or more on a stress loading part of the metal material, and maintaining a state in which the solution-retaining material is held at a deliquescence humidity of the chloride to thereby corrode the stress loading part.

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Tokyo, Japan

Naho Inoue