OUTER-LOOP CONTROL FOR USE WITH NICKEL AND DUPLEX STAINLESS STEEL FILLER ALLOYS AND CARBON DIOXIDE CONTAINING SHIELDING GAS

Abstract

A method of welding with high nickel content and duplex stainless steel electrodes using adaptive outer loop control to change at least one of a peak current or pulse frequency of a pulse waveform used for welding. The pulse waveform is changed based on a detected change in contact tip to work distance between the electrode and the work piece. The arc generated between the work piece and the electrode is shielded by a shielding gas which contains carbon dioxide and an inert gas.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects of the invention will be more apparent by describing in detail exemplary embodiments of the invention with reference to the accompanying drawings, in which:

FIG. 1 illustrates an embodiment of a control system used with the present invention;

FIG. 2 illustrates a single pulsed waveform in accordance with an embodiment of the invention; and

FIG. 3 illustrates a flow chart showing a method of an embodiment of the present invention.

Claims

1. A method of welding, the method comprising: generating a welding arc between an electrode and a work piece using a pulse waveform;shielding said welding arc with a shielding gas that contains carbon dioxide and at least one inert gas;detecting a change in said arc between said electrode and said work piece;changing at least a portion of the pulse waveform based on the detected change to create a second pulse waveform; andgenerating an additional welding arc between said electrode and said work piece using said second pulse waveform,wherein said electrode is either a duplex stainless steel electrode or a high nickel content electrode.

2. The method of welding of claim 1, wherein the amount of carbon dioxide in the shielding gas is in the range of about 0.05 to about 2.5%.

3. The method of welding of claim 1, wherein said detecting includes detecting a change in at least one of an arc length, an arc current, an arc energy and an arc voltage to detect said change in said arc.

4. The method of welding of claim 1, wherein both a pulse frequency and a peak current of said pulse waveform is changed to create said second pulse waveform.

5. The method of welding of claim 1, wherein at least one of a pulse frequency, peak current, peak current time, background current and background current time of said pulse waveform is changed to create said second pulse waveform.

6. The method of welding of claim 1, wherein the change in said arc is due to a change in distance between said electrode and said work piece.

7. The method of welding of claim 1, wherein said second pulse waveform is generated immediately following said pulse waveform.

8. The method of welding of claim 1, wherein said inert gas is made up of at least one of argon and helium.

9. A method of welding, the method comprising: generating a welding arc between an electrode and a work piece using a pulse waveform;shielding said welding arc with a shielding gas that contains about 0.05% to about 2.5% of carbon dioxide and at least one inert gas;detecting a change in said arc between said electrode and said work piece, where said change is a result of a change in distance between said electrode and said work piece;changing at least a portion of the pulse waveform based on the detected change to create a second pulse waveform; andgenerating an additional welding arc between said electrode and said work piece using said second pulse waveform,wherein said electrode is either a duplex stainless steel electrode or a high nickel content electrode.

10. The method of welding of claim 9, wherein said detecting includes detecting a change in at least one of an arc length, an arc current, an arc energy and an arc voltage to detect said change in said arc.

11. The method of welding of claim 9, wherein both a pulse frequency and a peak current of said pulse waveform is changed to create said second pulse waveform.

12. The method of welding of claim 9, wherein at least one of a pulse frequency, peak current, peak current time, background current and background current time of said pulse waveform is changed to create said second pulse waveform.

13. The method of welding of claim 9, wherein said second pulse waveform is generated immediately following said pulse waveform.

14. The method of welding of claim 9, wherein said inert gas is made up of at least one of argon and helium.

15. A method of welding, the method comprising: generating a welding arc between an electrode and a work piece using a pulse waveform;shielding said welding arc with a shielding gas that contains carbon dioxide and at least one inert gas;detecting a change in said arc between said electrode and said work piece, where said change is a result of a change in distance between said electrode and said work piece;changing at least one of a peak current and a pulse frequency of the pulse waveform based on the detected change to create a second pulse waveform; andgenerating an additional welding arc between said electrode and said work piece using said second pulse waveform,wherein said electrode is either a duplex stainless steel electrode or a high nickel content electrode.

16. The method of welding of claim 15, wherein the amount of carbon dioxide in the shielding gas is in the range of about 0.05 to about 2.5%.

17. The method of welding of claim 15, wherein said detecting includes detecting a change in at least one of an arc length, an arc current, an arc energy and an arc voltage to detect said change in said arc.

18. The method of welding of claim 15, wherein at least one of a peak current time, background current and background current time of said pulse waveform is also changed to create said second pulse waveform.

19. The method of welding of claim 15, wherein said second pulse waveform is generated immediately following said pulse waveform.

20. The method of welding of claim 15, wherein said inert gas is made up of at least one of argon and helium.