METHOD OF PREPARING SPECIMEN FOR EVALUATION OF METALLIC MATERIAL CHARACTERISTIC AND CHARACTERISTIC EVALUATION METHOD

• Main Author: KAWAHARA YOSHIYUKI
• Format: Patent
• Language: English; Japanese
• Published: 05.04.2018
• Subjects: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; MEASURING; PHYSICS; TESTING

PROBLEM TO BE SOLVED: To provide a method of preparing a specimen for evaluation of metallic material characteristic and a characteristic evaluation method which allow for more proper evaluation of thermal degradation of the metallic material.SOLUTION: A method of preparing a specimen for evaluation of metallic material characteristic comprises: a step of heat-treating the metallic material so that work hardening of the metallic material is restored; a step of determining a threshold value of the cooling rate of the heat-treated metallic material; and a step of forming the specimen for characteristic evaluation by cooling the heat-treated metallic material at a cooling rate that is the threshold value or less in at least one of temperature range. The step of determining the threshold value is performed in such way that a plurality of specimens constituted of the same material as the metallic material are heat-treated, the heat-treated specimens are respectively cooled at a plurality of cooling rates, and relationship between the cooling rate and conductivity index of the cooled specimen is obtained, the cooling rate of the second range of the cooling rate is determined as the threshold value on the basis of the relationship when the cooling rate is smaller than that of a first range of the cooling rate, and absolute value of conductivity index inclination to the cooling rate is small than that of the first range.SELECTED DRAWING: Figure 3 【課題】金属材料の熱劣化をより適切に評価し得る、金属材料の特性評価用試料の作製方法及び特性評価方法を提供する。【解決手段】金属材料の特性評価用試料の作製方法は、金属材料の加工硬化が回復するように金属材料を熱処理するステップと、熱処理された金属材料の冷却速度の閾値を決定するステップと、熱処理された金属材料を、少なくとも一部の温度領域において、閾値以下の冷却速度で冷却して、特性評価用試料を形成するステップと、を備え、閾値を決定するステップは、金属材料と同一材料の金属により構成される複数の試料を熱処理し、熱処理後の複数の試料を複数の冷却速度の下でそれぞれ冷却し、冷却速度と冷却後の試料の導電率指標との相関関係から、冷却速度の第１範囲よりも冷却速度が小さく、且つ、導電率指標の冷却速度に対する傾きの絶対値が第１範囲よりも小さい冷却速度の第２範囲の冷却速度を閾値として決定する。【選択図】図３