単層及び多重溶接熱サイクル再現溶接熱影響部の靱性に及ぼす島状マルテンサイトの挙動に関する検討 : 80及び100キロ級高張力鋼大入熱溶接HAZ部の靱性劣化とその改善に関する研究(第1報)

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In this research work, the effect of area fraction of M-A constituent on charpy absorbed energy (_vE) of both simulated-CGHAZ (Coarse-Grained HAZ for high heat input welding process) and ICCGHAZ (Intercritically-Reheated CGHAZ for multiple welding process) of either 780 or 980 MPa class HSLA steel has been studied. The M-A constituent is classified into two types such as massive M-A and elongated M-A depending on its form. The form of M-A changes from "elongated M-A" to "elongated M-A+massive M-A" and then to "elongated M-A+massive M-A+carbide" according to the increase of cooling time, Δ_<t8/5>. Furthermore, the size of M-A increases. It has been clarified that the _vE of ICCGHAZ is rather lower than that of CGHAZ as the result of dual thermal cycle test at the temperature of 1073 K where the peak temperature of second thermal cycle, T_<p2> exceeds A_<c1> due to the formation of massive M-A of large size. However, the _vE at both 873 K and 673 K where the peak temperature of third thermal cycle, T_<p3> is lower than A_<c1> is improved to be more than the _vE at temperature of 1073 K which is equal to T_<p3> in the triple thermal cycle test. Since these improvement of _vE considerably corresponds with the decrease of area fraction of M-A, the M-A constituent is decomposed by the tempering effect of third thermal cycle so that the _vE value of ICCGHAZ seems to have been improved. The increase of area fraction of total M-A in both single and multiple welding thermal cycle tests causes the increase of that of massive M-A seems to be the decisive factor for the deterioration of _vE in both CGHAZ and ICCGHAZ of either 780 or 980 MPa class HSLA steel.
社団法人溶接学会の論文
1994-02-05

単層及び多重溶接熱サイクル再現溶接熱影響部の靱性に及ぼす島状マルテンサイトの挙動に関する検討 : 80及び100キロ級高張力鋼大入熱溶接HAZ部の靱性劣化とその改善に関する研究(第1報)

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