Interpasstemperatuur

Interpasstemperatuur, or interpass temperature, is the temperature of the weld area in a multi-pass weld between successive passes, typically measured on the base metal just ahead of the weld pool. The exact value to aim for is specified in the welding procedure specification (WPS) and depends on factors such as material, thickness, welding process, and filler metal.

Maintaining an appropriate interpass temperature helps control the metallurgical state and mechanical properties of the weld. Proper interpass temperatures can reduce undesirable effects such as excessive grain growth, carbide precipitation or sensitization in stainless steels, and the accumulation of residual stresses. Conversely, too low temperatures can hinder proper fusion or impede hydrogen diffusion, increasing the risk of hydrogen-assisted cracking, while too high temperatures can worsen distortion and weaken toughness.

Control of interpass temperature is achieved through preheating before welding, managing the heat input during successive passes, and allowing controlled cooling or using insulation, heat blankets, or active cooling as needed. Temperature is typically monitored with infrared thermometers, thermocouples, or data-logging sensors to ensure conformity with the WPS.

In industry practice, interpass temperature limits are part of quality control and are referenced in codes, standards, and WPS documents. Welders and inspectors verify temperatures between passes; if the limit is exceeded, welding may be paused to recool, preheating may be adjusted, or corrective actions such as re-welding or post-weld heat treatment may be required depending on the procedure.