When ESAB China had fracture toughness tests carried out by Tianjin University, some showed pop-in features on the CTOD test traces. Unsure whether these were metallurgical effects, a consequence of out-of-date testing and data logging equipment, or due to specimen preparation technicalities, ESAB asked TWI to help.
ESAB China asked TWI to deliver a training course on CTOD testing for delegates from Tianjin University and ESAB to help all sides understand the complexities of fracture mechanics testing, to look at potential causes of pop-ins, and how to conform to the current standards for specimen preparation, testing and analysis.
Dr Philippa Moore and Dr Henryk Pisarski went to Tianjin to give the presentations (translated into Chinese by ESAB), and to witness CTOD tests in the Tianjin University laboratories.
The previous month Tianjin University had begun using a new fracture toughness testing machine, with fully computerised data logging system, so TWI's experts could help them optimise the CTOD tests using their new capability.
Suggestions were given to help improve the test methodology and assessment of pop-ins, and tests on a new ESAB consumable were witnessed. Guidance was also given on the changes with the new fracture toughness testing standard for weld specimens (ISO 15653).
ESAB was happy to gain confidence in Tianjin University's testing procedures, and for their new specimens to show good fracture toughness behaviour. Tianjin University was happy to know that they have a generally good testing method, and to know ways to make their testing service even better. TWI was happy to have received such a warm welcome in China from both ESAB and the University.