18% Cr鋼の溶接部の靱性におよぼす合金元素の影響

抄録

Measurements of vTrs and absorbed energy of 18%Cr steel and its welds by V-notch Carpy impact test were carried out in the temperature range from-80 to 140°C in order to clarify the effects of alloying elements on the toughness of the steel and welds. The specimens of welds were prepared from 3.2mm hot rolled andannealed plate by TIG (tongsten inert gas) meet run with I-grooved joint without filler. The toughness of the specimen was evaluated from the values obtained from the Charpy impact test.
The main results obtained are as follows;
1) The transition curves of the base metal and welds are remarkably shifted to lower temperatures with decreasing the contents of carbon and nitrogen and adding the proper amounts of titanium and manganese.
2) The ductile-brittle transition temperatures lower to a large extent with adding the proper contents of titanium and also making the structure of steel become a single phase of ferrite.
3) Manganese addition strengthens the weld metal by solution-hardening and simultaneously disperses the precipitation of flaky chromium carbides of M₇C₃ and M₂₃C₆, and consequently improves the toughness of the welds remarkably.