Читать книгу Welding Metallurgy - Sindo Kou - Страница 102

Example 3.1 It has been observed in GTAW shielded by a He gas containing CO₂ that the depth/width ratio of the weld increases with increasing CO₂ content [72]. Assume the Lorentz force is small because of the low welding current used. (a) Sketch the surface tension distribution along the pool surface with pure He shielding. (b) Sketch the flow pattern in the weld pool with pure He shielding. (c) How does CO₂ affect the O content in the weld pool? Give the chemical reaction(s) involved. Sketch the surface tension distribution along the pool surface with He/CO₂ shielding. (d) Sketch the flow pattern in the weld pool with He/CO₂ shielding. Why does the depth/width ratio increase with increasing CO₂ content in the shielding gas?