1979 Volume 48 Issue 7 Pages 520-525
Implant test has following merits: Data on cold cracking susceptibility are easily obtained from small size specimens as compared with self-restrained weld cracking test like Lehigh test, RRC test etc..Implant test is valuable in economical sense. However, implant test has its inherent disadvantage; several experiments have suggested that it has been apparently difficult to apply directly the critical stress and/or the critical cooling time obtained from implant test to welding procedure in RRC test which is considered as welded joint of real structures. In the present report, attention is forcussed to determine correlation between RRC test and implant test. Firstly implant-and RRC-test are carried out under various conditions of materials and preheat temperatures. Secondly two dimensional finite element method based on elasto-plastic theory is carried out to find out the parameter determing initiation of cold cracking from the standpoint of engineering.
The conclusions obtained in this report are summarized as follows:
1. It is concluded from comparison of implant-test results with RRC-test results that the local stress in loading direction at region where cold cracking starts becomes engineering parameter of cold cracking.
2. Correlation between the critical net stress of implant test (σIpm)cr and the critical net stress of RRC test (σRRC)cr is given in following equation from engineering sense stand point
(σIpm)cr = (K1)RRC/(K1)lmp (σRRC)cr
where, (Kt)Imp is stress concentration factor of implant specimen and (Kt)RRO is stress concentration factor of RRC specimen.