Heat flux density distribution
The heat flux density distribution describes how strongly the arc heats the metal surface. An uneven distribution can lead to non-uniform melting and stresses.
Physical-Chemical Mechanism of Action
The arc emits thermal energy as radiation. The intensity of this radiation varies across the arc surface and is projected onto the metal surface. The higher the heat flux density at a point, the faster the metal heats up there.
Metallurgical Relevance & Welding Risks
Uneven heat flux density distribution can cause the following problems:
• Uneven melting: Parts of the steel melt faster or slower, leading to stress and distortion.
• Stress buildup: Uneven heating can cause local stresses within the material structure, which can lead to cracks and fractures.
• Weld wear: Unevenly heated areas can accelerate wear processes in the weld.
Workshop Practice & Procedures
To ensure good heat flux density distribution, follow these measures:
• Arc positioning: Set the arc so that heat is distributed evenly across the weld. This can be achieved by adjusting the distance and angle.
• Shielding: Use a shield to block unwanted radiation and ensure even heating.
• Travel speed: Adjust travel speed to match the heat flux density distribution. Too fast can cause uneven heating, while too slow can create stress and distortion.