Estimation of tendency of welded joints of nickel alloys to cracks formation in heat treatments

Comparative tests of welded joints of EP99, EP199, EP708 and EP693 alloys are carried out for choice of the most reliable evaluation criterion by means of a disk technological sample with 130 mm diameter, 3 mm thickness with ring-shaped weld of 25 mm diameter, exercised by manual argon-arc welding with EP533 additional wire. Welding was conducted after hardening. Then some samples were held at 800 deg C during 15 hours with the following measuring summary crack length, and other samples were used for determination of time up to crack formation. It is shown, that the suggested test method under loading conditions by two-axial bend permits to give a comparative quantitative resistance evaluation of nickel alloy welded joints to crack formation during heat treatment. Evaluation by initial deflection or stress during welded joint tests under the conditions of loading with two-axial bend is characterized by less variability of experimental data, than evaluation by summary crack length or time before fracture according to the results of tests of naturally stressed samples. The test method is not worse by sensitivity to cracking, than tests of hard technological samples