2Vシャルピ衝撃試験の破面遷移温度とCOD試験による脆性破壊発生温度との相関

抄録

The relationship between the fracture appearance transition temperature _υT_rs in the V-notch Charpy test and the brittle fracture initiation temperature in the COD test has been investigated. The obtained results can be summarized as follows:-
(1) The relationship can be expressed by the equation,
[T_δ]^σ=σ_c=c = (0.006121δ_y+0.4704)_νT_rs+8.26√t+0.608δ_y[{1n(c/40)(2σ/δ_y)²}+{c(2σ/δ_y)²-40}/100]-90.2(°K)
where [T_δ]^σ=σ_c=c is the critical temperature at which the brittle fracture is initiated in an infinite plate with a crack of a length 2C and application of an uniform stress σ, δ_y is the nominal yield strength and t is the thickness of steel plates.
(2) For preventing brittle fracture in welded structures made with HT60 or HT80, the required value of _νT_rs for the welds should be lowered with an increase in the strength and the thickness of steel plates, the design stress and the length of the crack in the welds. And the maximum acceptable crack length should be decreased with an increase in the strength and the thickness of steel plates, the design stress and _νT_rs.
(3) The maximum acceptable crack length, for preventing brittle fracture in welds of HT60 or HT80 welded with the same heat input of 40-50 kj/cm, increases with the plate thickness up to the thickness of 40 mm and decreases with the plate thickness in a range of more than 40 mm.