FISCO Testerによるオーステナイト系ステンレス溶着鋼の溶接高温亀裂について(第1報)

Abstract

As a part of the study of hot cracking with FISCO Tester, the following investigations were performed, (1) On the reproducibility of FISCO test result(2) On the effect of chromium contents and nickel contents in modified type D310 weld metal(3) The estimation of hot cracking temperatureand the following results were obtained.(1) By testing the hot crack sensitivity of austenitic stainless steel weld metal with FISCO Tester were obtained the results in accordance with the experiences in the past.The maximum confidence limits in population mean of crack sensitivity were as follows. (Confidence 95%)f4(%)=16.7±1.4 on type D347, 4 mmφ with SUS7, A.C. 140 amp.f3(%)=25.2±3.3 on type D310, 3.2mmφ with SUS12, D.C.R. 100 amp.(2) As nickel contents were increased in modified type D310 weld metal, to both SUS7-SM41W and SUS12-SUS12 butt welding, the crack sensitivity had the tendency to be increased.As chromium contents were increased in the same type weld metal, to both butt welding, the crack sensitivity was reduced.(3) On the basis of the coloring tendency of various stainless steel materials at high temperature, hot cracking temperature was observed.It was estimated for D316L and D347 weld metal that hot cracking at above 1000°C (1832°F) was limited to very small portion on the upper part in crater zone and cracking at 400°C (752°F) to 700°C (1292°F) occured for the most part. For D310 weld metal, hot cracking at above 1000°C occured on all upper part in crater zone. Hot cracking at above 1000°C in started zone occured on the lower limitted portion, on another portion at 400°C to 700°C. Cracking in middle zone occured only at 400°C to 700°C.