Method for automated testing of a material joint

A method for automated, contactless and non-destructive testing of a material joint (4) of at least two mating parts (2, 3),

• a. with the material joint (4) being a two-section joint which consists of
• i. a molten zone (5) and
• ii. a non-molten zone (6) surrounding said molten zone (5);
• b. with an examination of infrared images taking place in such a way that
• i. at least one excitation source (8) excites a test sample (1);
• ii. at least one infrared sensor (9) detects a developing heat flow in a sequence of thermal images;
• iii. result images are obtained from the sequence of thermal images;
• and
• iv. the thermal images and the result images are examined;
• wherein
• c. the molten zone (5) is detected from a result image, which illustrates a heat flow dynamics (W) through the material joint (4), in such a way that
• i. a minimum threshold value (Wmin) is determined which exceeds a heat flow dynamics (W) of an image background (H);
• ii. a maximum threshold value (Wmax) is determined which corresponds to a peak value of the heat flow dynamics (W) through the material joint (4);
• iii. a dynamic threshold value (Wdyn) is varied between the minimum threshold value (Wmin) and the maximum threshold value (Wmax);
• iv. a sequence of regions (B) of the heat flow dynamics (W) through the material joint (4) is determined which represent the values of the heat flow dynamics (W) exceeding the dynamic threshold value (Wdyn);
• v. the regions (B) of the heat flow dynamics (W) are examined with respect to an abrupt change in perimeter (ΔU);
• vi. the molten zone (5) is determined as a region (Bi) from the regions (B), the abrupt change in perimeter (ΔU) indicating that a boundary (7) between the molten zone (5) and the non-molten zone (6) is being crossed;
• and
• vii. a position and a size of the molten zone (5) are evaluated.