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■■■■■■■■■■■■■■■■■■■ 川崎製鉄技報 KAWASAKI STEEL GIHO Vol.17 (1985) No.1 ■■■■■■■■■■■■■■■■■■■ |
| 新制御圧延法TMCPにより製造した50 kgf/mm2級高張力鋼の疲労特性 Fatigue Properties of 50 kgf/mm2 High Tensile Strength Ship Hull Structural Steel Manufactured by Thermomechanical Control Process 松本 重人(Shigeto Matsumoto) 成本 朝雄(Asao Narumoto) 志賀 千晃(Chiaki Shiga) 上田 修三(Syuzo Ueda) |
| 要旨 : 新制御圧延法(TMCP)による50 kgf/mm2級高張力鋼の疲労特性を述べた。TMPC材は優れた溶接性と高じん性を有するが，疲労強度の観点から板厚方向疲労特性と大入熱溶接熱影響部(HAZ)軟化の影響を調査した。板厚方向疲労強度はS含有量が同程度の従来材と同等であり，TMCP法による特異性はみられない。HAZ軟化による疲労強度の低下は平滑材で最大15％，切欠材Kt=3で10％程度，き裂伝播特性はパリス則の指数m値の変化は0.2以下と予想され，ほぼ無視し得る量である。このことから新制御圧延材の疲労強度,き裂伝播特性とも従来材と同等で問題ないことを確認した。 |
| Synopsis : Fatigue properties of newly developed steels with a tensile strength 50 kgf/mm2 grade, which are manufactured by Kawasaki Thermomechanical Rolling (KTR) and Multipurpose Accelerated Cooling System (MACS), are reported. The newly developed steels exhibit excellent weldability and low-temperature toughness. From the view point of fatigue strength, an investigation has been made on their fatigue properties in the through-thickness direction and on the softening of their high heat input welded joints. The relationship between the through-thickness fatigue strength and sulphur content only was obtained for KTR, MACS and conventional steels. There was no other factor which affects the through-thickness fatigue strength of newly developed steels. Reduction in fatigue strength due to the softening of HAZ was less than 15％ when Kt was 1 and less than 10％ when Kt was 3. Change in the value of m in Paris' formula due to the softening of HAZ was predicted to be 0.2, which was negligibly small. Base metal and high heat input welded joints of newly developed controlled rolled steels revealed excellent fatigue properties. |
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