The Effect of Pressure on Mechanical Properties of Welded Joints : On Gravity Arc Welding under High Pressure Atmosphere

概要

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The effect of ambient pressure on mechanical properties of mild steel welded joints obtained by the gravity arc welding process was investigated. Welding was executed by low hydrogen type electrode of 4 mm in diameter under pressure range from 0.1 to 5.1 MPa(abs.). As base metals, SM41A steel plates of 6 and 9 mm in thickness were used. Main results obtained are summarized as follows : 1) Charpy impact value of weld metal decreases considerably with an increasing pressure. The tensile strength and the elongation decrease somewhat and the average hardness increases slightly with it. 2) As the pressure increases, volume of pearlite in weld metal increases and the structure tends to be bainitic. The grain size of dendrite tends to decrease. 3) As the pressure increases, the content of diffusible hydrogen in deposited metal (H_D) increases up to about 1 MPa, but it tends to decrease over that pressure. 4) As the pressure increases, the contents of Si and Mn in weld metal decrease, but the contents of C and O increase considerably. The contents of P and S are approximately constant regardless of pressure. 5) As the ambient pressure increases, mechanical properties of weld metal deteriorate, because the contents of C, O and H in weld metal increase.
社団法人溶接学会の論文
1991-04-01