Root Cracking and Maximum Hardness in High-Strength Steel Welds
スポンサーリンク
概要
- 論文の詳細を見る
Effects of maximum hardness in the HAZ on root crack initiation in the JIS-y (oblique- Y groove) cracking test are discussed. The values of critical hydrogen concentration Hc at the location of root crack initiation at 100゜C during cooling, were calculated assuming uniform diffusion of hydrogen through the weld zone. Hc is proportional to the deposited diffusible hydrogen content H_D and is a function of cooling time t_100, from solidification to 100゜C. The values of log Hc decreased linearly with an increase of Hmax, depending on the intensity of restraint or specimen thickness. The correlation between log Hc and Hmax was found to be far less good than that between log Hc and Pcm (Ito-Bessyo carbon equivalent) which is adequate only for low carbon content steels. An analysis by the cracking parameter P_HA, proposed by the author considering local accumulation of hydrogen at the point of stress concentration and root crack initiation, revealed that log Hc vs. Hmax relation is severely affected by the carbon content of test steel, thus causing a wide scatter in Hc values in the log Hc-Hmax diagram. For the same value of Hmax, a lower carbon content is more desirable for prevention of root cracking. The values of critical Hmax for crack-free welding without preheating and with 100゜C preheating have been P_HA-estimated to show the effects of hydrogen content and of a wide range of intensities of restraint. A carbon content of 010% is far superior to 0.15% content to secure the Hmax value of less than, for example, 325 Hv in practical fabrication of offshore steel structures. The P_HA-estimates of critical Hmax values agree satisfactorily with experimental values reported by othrr researchers. Moreover a new formula is proposed to estimate satisfactorily the Hmax value simply from carbon content, Pcm and cooling time t8/5.
- 社団法人溶接学会の論文
- 1984-04-01
著者
関連論文
- Prevention Against Cold Cracking by the Hydrogen Accumulation Cracking Parameter P_
- Root Cracking and Maximum Hardness in High-Strength Steel Welds
- Carbon Equivalent and Maximum Hardness