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Test: checking the hardness of the welds


checking_the_hardness_of_the_welds.jpgCustomer:  heat exchangers and heating equipment manufacturer.

Task: to check the hardness of welds after machining. The thickness of the pieces to be welded is 1,5-100 mm (0.059-3.9 inches). The material given is "ST-20" steel.

Hypothesis and preparation for the experiment: we decided that UCI TKM-459CE Hardness Tester would cope with the task and asked the customer to send us the samples. We received 7 samples with thickness of 3 mm (0,11 inches).

To obtain the weight parameter necessary to use the UCI method we rubbed the samples to the base plate using the "Tsiatim" lubricant. Our metrologists made measurements at two areas of each sample:

  • at the welds themselves (they were grindered in advance to achieve a desirable roughness of 1.6 RA)
  • near the welds.

On the picture to the right the respective areas are circled.

In some areas the measurement failed (on the picture they are marked with crosses).

uci_hardness_tester_tkm-459ce_3.jpgThe results: We prepared a detailed report based on the experiment results, and we sent it to the customer. The standard deviation was calculated for each tested zone separately and turned out to be quite high (from 0.2 to 3.5), especially after the considering the test blocks.

We believe that the reason was the pieces for testing were not duly prepared.

Nevertheless the customer accepted the variability of the results, the same as our tips on the choosing of the area for testing on the real objects.

TKM-459CE UCI hardness tester became the choice of our client.

Learn more here: Testing non-standard metals and alloys >>>