What is interpass temperature and why is it controlled?

What is interpass temperature and why is it controlled?

• A. Temperature of base metal before welding
• B. Temperature of the shielding gas
• C. Temperature of the welding power supply
• D. Temperature of the weld area between passes

Answer: (D)

Interpass temperature is the temperature of the weld area between successive passes in a multi-pass weld. It’s controlled because the heat history of the weld area directly influences the metallurgy and integrity of the joint. If the temperature between passes gets too high, you can get excessive grain growth, reduced toughness, distortion, and cracking, and the next pass may not fuse properly. If it’s kept too low, the next weld pass may not bond well, leading to poor fusion and residual stresses. By holding this temperature in a specified range, you promote consistent fusion between passes, maintain desirable mechanical properties, and minimize defects. Measurement is typically done with an infrared thermometer or thermocouples between passes, and codes or procedure specs often set the allowable range. This concept is not about the base metal preheat, the shielding gas, or the power supply settings—it's specifically the weld area temperature between passes.

Interpass temperature is the temperature of the weld area between successive passes in a multi-pass weld. It’s controlled because the heat history of the weld area directly influences the metallurgy and integrity of the joint. If the temperature between passes gets too high, you can get excessive grain growth, reduced toughness, distortion, and cracking, and the next pass may not fuse properly. If it’s kept too low, the next weld pass may not bond well, leading to poor fusion and residual stresses. By holding this temperature in a specified range, you promote consistent fusion between passes, maintain desirable mechanical properties, and minimize defects. Measurement is typically done with an infrared thermometer or thermocouples between passes, and codes or procedure specs often set the allowable range. This concept is not about the base metal preheat, the shielding gas, or the power supply settings—it's specifically the weld area temperature between passes.