For the corrosion protection of the natural gas transmission pipelines, two methods are used, cathodic protection and a coating technique. In the case of cathodic protection, defects are embrittled by occurring hydrogen at the crack tip or material su...
For the corrosion protection of the natural gas transmission pipelines, two methods are used, cathodic protection and a coating technique. In the case of cathodic protection, defects are embrittled by occurring hydrogen at the crack tip or material surface. It is however very important to evaluate whether cracks in the embrittled area can grow or not, especially in weld metal. In this work, on the basis of elastic plastic fracture mechanics, we performed CTOD testing with varying test conditions, such as the potential and current density. The CTOD of the base steel and weld metal showed a strong dependence of the test conditions. The CTOD decreased with increasing potential and current density. The morphology of the fracture surface showed quasi-cleavage. Hydrogen introduced fractures, caused by cathodic overprotection