Ni 合金およびオーステナイト系ステンレス鋼多層溶接金属部のミクロ割れについて(第 1 報) : Ni 合金多層溶接金属部のビード下ミクロ割れの特性

概要

論文の詳細を見る
Multirun welds of 25Cr-20Ni steel, 18Cr-10Ni-Nb steel and Inconel are susceptible to microcracking (under-bead microcracking in weld metal) in underlying weld runs. To study the mechanism of this under-bead microcracking, Inconel multirun weld deposits were made in the form of pads on mild steel plate, using widely varying heat inputs and interpass temperature. The results obtained in the present study are as follows : 1. Microcracks were observed in the previous-layer weld metal reheated by the heat of subsequent bead, when welds were made on the mild steel dipped partially in water of about 20℃ in order to lower interpass temperature. 2. No microcrack, however, was found when preheating was applied at about 150℃. 3. The degree of microcracking increased with decreasing heat input, particularly with increasing welding speed. 4. Metallographic examination and weld thermal stress analysis were carried out. And the mechanism of under-bead microcracking was discussed. As a result, it is concluded that (1) the under-bead microcracking occurs in the heating process of the heat cycle due to subsequent bead, and (2) precipitous thermal gradient causes high thermal strain and induces microcracking.
社団法人溶接学会の論文
1982-12-05