Oxygen Content and Fracture Toughness of MIG Weld Metal of SUS304 Steel

概要

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In the gas shield arc welding with SUS304 austenitic stainless steel base metal and JIS Y30L type electrode, the effect of the welding condition on the oxygen content and microstructure of weld metal has been investigated. Next, the effect of oxygen on the mechanical properties, mainly on the fracture toughness, was studied. The main results are summarized as follows: 1) The oxygen content of weld metal is increased with a dicreasing welding current (from 200A to 400A) and with an increasing arc voltage (from 20V to 30V). In the constant welding atmosphere, there is a linear correlation between the oxygen content and a parameter A/V which is introduced by the authors, where A is welding current and V is arc voltage. The oxygen content decreases with an increasing parameter A/V. 2) Most of oxygen exists in the γ region as a spherical oxide of Mn-silicate. The number of oxides per unit volume is related to the welding heat input. It decreases with an increasing heat input. 3) Charpy impact values and J_<in> values decrease with an increasing oxide volume fraction. 4) The relationship between Charpy impact value and oxide volume fraction is represented by a straight line on the log-log cordinate. At the constant oxide volume fraction, the distribution (number and size) of oxides has little effect on Charpy impact value.
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1987-10-01