Effect of Alloying Elements on Nitrogen Content of Steel Weld Metals (Report 2)

Welding in air atmosphere

Abstract

Using ten series of alloy steel electrode wires, mild steel was welded in an air atmosphere.
The individual influence of the alloying elements, C, Si, Mn, Nb, Mo, V, Co, Ta, W and Cu in the electrode wires on the nitrogen content of weld metals deposited at three current levels was systematically studied.
The results are summarized as follows;
1) The alloying elements in steel electrodes can be divided into the following three groups by the type of their influences on the nitrogen content of weld metals obtained in an air atmosphere;
(I) Nb, V, Ta, Mn, Al, Ti, Zr
(II) C, Si,
(III) Cu, Co, Mo, W
2) The elements in group (I) alloyed up to a certain amount reduce the nitrogen content of weld metals and an excess amount of them again increases the nitrogen content, at low welding currents. At high currents, the elements in group (I) generally increase the nitrogen content of weld metals.
3) The elements in group (II) reduce the nitrogen content of weld metals both at low and high currents.
4) The elements in group (III) have no important influence upon the nitrogen content.
5) The individual influence of the element can be explained satisfactorily with its affinity to oxygen and its influence on the solubility of nitrogen in molten iron.