How to properly use basic low-hydrogen welding electrodes?

The use of basic low-hydrogen welding electrodes requires careful attention, focusing on three key points: pre-welding drying, thorough cleaning, and standardized operation. Mastering these points ensures weld quality.

I. Pre-welding Preparation
Electrode Drying: Electrodes must be baked at 350-400℃ for 1-2 hours, then stored in a 100-150℃ insulated container for use as needed to prevent moisture absorption.
Workpiece Cleaning: Thoroughly remove rust, oil, moisture, and other impurities from within 25mm of the weld seam.
Power Source Selection: A DC welding machine must be used, employing reverse polarity (electrode connected to the positive terminal, workpiece to the negative terminal).
II. Welding Operation Essentials
Short Arc Welding: Maintain an arc length shorter than the electrode diameter (usually 1.5-3mm) to effectively prevent porosity.
Standardized Welding Technique:
Straight Line Welding: Suitable for the first layer of flat welding; the weld bead should be narrow.
Small Amplitude Oscillation: Slight oscillation is permissible for wider welds, but a short arc must be maintained.
Current and Speed: The welding current should be 10-15% lower than that of acidic electrodes of the same specification, and the welding speed should be slightly faster.
III. Key Precautions
Arc Initiation: Use the scratching method. After striking the arc, lower the arc and hold it briefly to prevent porosity at the weld end.
Joints: New weld joints should be initiated 20-80mm in front of the previous weld crater, or an arc starting plate should be used.
Safety Protection: Ensure adequate ventilation to prevent inhalation of fluorine-containing fumes; wear a protective face mask during welding.
IV. Troubleshooting Common Problems
Electrode Reddening and Coating Cracking: This may be due to excessive baking temperature or heating speed. Heating should be slow and controlled.
Porosity in the Weld: Check if the electrodes are properly dried, the workpiece is clean, and short arc welding is being used.
Electrode Sticking: Check if the polarity is DC reverse polarity, increase the open-circuit voltage to above 70V, and shorten the arc length.

Summary: The core principles for using basic low-hydrogen welding electrodes are "dryness, cleanliness, and standardization." Strictly following the drying, cleaning, and short-arc welding procedures is crucial for obtaining high-quality welds.