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Improvement of Reliability of Welded Joint by Laser Peening - Rendering a Surface Defect Harmless -

通过激光喷丸提高焊接接头的可靠性 - 使表面缺陷无害化 -

基本信息

批准号：
17J00191
负责人：
笛木隆太郎
金额：
$ 1.22万
依托单位：
Yokohama National University
依托单位国家：
日本
项目类别：
Grant-in-Aid for JSPS Fellows
财政年份：
2017
资助国家：
日本
起止时间：
2017-04-26 至 2019-03-31
项目状态：
已结题

项目摘要

本年度の研究成果を下記の(1)～(5)に示す。(1) 前年度に決定したステンレス鋼に対するレーザピーニング（LP）の最適施工条件でLPを施工した溶接試験片を用意し，一部の試験片には溶接止端部近傍に人工表面欠陥（半円スリット）を導入した上で，疲労試験を実施した。LPの施工により，疲労限度は14%～64%改善されるとともに，深さ0.2 mmのスリットが無害化されることが明らかになった。(2) 高張力鋼について，LPの最適施工条件を決定した後，上記(1)と同様のプロセスで疲労試験を実施した。LPの施工により，疲労限度は45%～107%改善されるとともに，深さ0.2 mmのスリットが無害化された。(3) 上記(2)で使用したものと同じ高張力鋼の溶接試験片に対してニードルピーニング（NP）を施工した場合の疲労限度改善率は9%～200%，無害化可能欠陥寸法は深さ1.0 mmであることがわかった。(4) 前年度に実施した実験を含む一連の実験結果を比較検討した結果，無害化可能欠陥寸法の大きさはピーニングにより導入される深さ方向の残留応力分布の様態に大きく依存し，その大きさは必ずしも残留応力が圧縮から引張に変化する深さに比例して大きくなるわけではなく，そこに至るまでの各深さにおいて、大きな圧縮残留応力が導入されることが重要であることがわかった。(5) ピーニング施工後の疲労限度相当の作用応力分布ならびに残留応力分布より応力拡大係数を評価し，それらを足し合わせたき裂進展に寄与する正味の応力拡大係数範囲の値を，き裂進展抵抗を表す下限界応力拡大係数範囲と大小比較することにより，ピーニングにより無害化可能な欠陥寸法を定量的に評価した。その評価値はステンレス鋼，高張力鋼ともに，LPの場合で0.2 mm前後，NPの場合で1.4 mm前後であり，実験結果と整合していたことから，評価法の妥当性が示された。

The results of this year's research will be shown in (1) ~ (5). (1) in the previous year, it was decided that there was an artificial surface defect near the end of the fusion test film "intention" in the latest construction condition "LP" (LP) in the previous year. The artificial surface defect near the end of the dissolving end was found to be in place, and the fatigue was applied. The fatigue limit of LP is 14% and 64%. The fatigue limit is 64%. The fatigue limit is 14%. The fatigue limit is 64%. The fatigue limit is 64%. The fatigue limit is 14%. The fatigue limit is 64%. The fatigue limit is 64%. The fatigue limit is 14%. The fatigue limit is 64%. (2) after the construction conditions of LP are determined, (1) after the construction conditions are determined, (1) after the construction conditions are determined, (1) after the construction conditions have been determined, (1) after the construction conditions have been determined, (1) after the construction conditions have been determined, (1) after the construction conditions have been decided, please do so. The fatigue limit of LP is 45% and 107%. The fatigue limit is 107%. The fatigue limit is 45%. The fatigue limit is 107%. The fatigue limit is 107%. The fatigue limit is 45%. The fatigue limit is 107%. The fatigue limit is 107%. The fatigue limit is 45%. The fatigue limit is 107%. The fatigue limit is 107%. The fatigue limit is 45%. The fatigue limit is 107%. The fatigue limit is 107%. The fatigue limit is 45%. The fatigue limit is 107%. The fatigue limit is 107%. (3) in the previous section (2), the improvement rate of fatigue limit in construction was 9% 200%, which may be less than 1. 0% of the total fatigue limit of mm test film. (3) the improvement rate of fatigue limit of NP may be less than 1. 0%. (4) in the previous year, the results of the previous year have been compared with the results of the previous year, and the results may not be harmful. The residual force distribution in the deep direction may be lower than that in the previous year, and the residual force distribution in the deep direction may be lower than the previous year. From the bottom to the bottom, the residual force is very important. (5) after construction, the fatigue limit is equivalent to the effect of force distribution, residual force distribution, fatigue strength distribution, fatigue strength distribution, residual force distribution, fatigue strength distribution, residual force distribution, residual force distribution, fatigue strength distribution, residual force distribution, residual force distribution, fatigue strength distribution, residual force distribution, fatigue strength distribution, fatigue strength distribution, residual force distribution, fatigue strength distribution, fatigue strength distribution, residual force distribution, fatigue strength distribution, fatigue strength distribution, residual force distribution, fatigue strength distribution, residual force distribution, residual force distribution, fatigue strength distribution, residual force distribution, fatigue strength distribution, residual force distribution, fatigue strength distribution, residual force distribution, residual force distribution, fatigue strength distribution, residual force distribution, fatigue strength distribution, residual force distribution, residual force distribution, fatigue strength distribution, fatigue strength distribution, residual force distribution, fatigue strength distribution, residual force distribution, residual force distribution, The amount of money that may be less than the amount of money required by the method may be harmless. The results showed that the combination of LP and NP before and after the integration of 0.2 mm and 1.4 mm, the results showed that there were significant differences between the two groups.