| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1988: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1987: ¥1,100,000 (Direct Cost: ¥1,100,000)
|
|---|
| Research Abstract |
Mild steel was welded in pressurized Ar,Ar-CO_2 and CO_2 atmospheres at pressure of up to 2.0MPa absolute,using a 1.6 mm diameter solid wire. The effects of ambient gas pressure and gas compositions on the arc phenomena, behaviour of alloying elements and mechanical properties of welds were studied.
Chamber pressure when increased acts to reduce appearance, weld width and arc stability,especially under pure CO_2 atmosphere. In pure Ar welding atmosphere,the electrode melting rate decreases with increasing the pressure. On the contrary,in CO_2 atmosphere,it increases with the increase of the pressure. The ambient pressure has no significant influence upon the loss of Si,Mn,C,Ti. But the oxygen content of weld made in Ar-CO_2 atmosphere and CO_22 atmosphere increases with increasing the pressure. The tensile properties of weld metals are varied with the ambient gas composition but are not affected by the gas pressure. CVN toughness of weld metals made in CO_2 atmosphere are deteriorated at increased pressure. The toughness of welds made in pressurized ar-CO_2 atmosphere are changed markedly by CO_2 partial pressure. It suggested that the CVN toughness are controlled by the oxygen content of welds.
|
