1978 Volume 47 Issue 10 Pages 697-704
In this report, joint performance tests of HT80 heavy plates for penstock with lower strength weld metal are carried out to investigate load-carrying capacity, joint ductility, brittle fracture initiation and fatigue behavior.
Test results obtained are summarized as follows:
(1) According'to the tension tests of transverse welded wide plate specimens free from appreciable weld flaws, joint strength σu and percent elongation εu in a large gauge length are given by the conventional formulas,
σu ≥ {0.87σWu+0.29σBu σBu when 0.7<σWu/σBu<0.82
when 0.82 ≤ σWu/σBu
εu ≥ 11(σWu/σBu)-6(%) when 0.7<σWu/σBu<1
in which σWu, σBu are tensile strength obtained by coupon test of weld metal and base plate respectively. The σu-value of the specimen welded with the JIS D 5816 type electrode is found to clear 80 kg/mm2 or the nominal tensile strength level of the base plate.
(2) As the results of fluctuating tensile fatigue test of butt welded specimen with reinforcement, fatigue crack is not suspected to initiate during service life of the penstock under planning even when the undermatching electrode is applied to circumferential weld connections. It is also found by the tension test of welded wide plate specimens with a surface notch at a weld fusion line that there is no difference in fracture strength at the temperatures ranging 0°C through-20°C between welded specimens made with the AWS E 11016 type and the JIS D 5816 type electrodes.
