Fracture toughness and fatigue crack growth properties of the base metal and weld metal of a type 304 stainless steel pipeline for LNG transmission

The fatigue crack growth rate and CTOD tests on type 304 stainless steel and weld metal were studied over the temperature range −162°C to room temperature. The girth weld metal specimens were fabricated using a combination of gas-tungsten-arc-welding and shielded-metal-arc-welding. The seam weld joint was made by submerged arc welding. Fracture toughness was evaluated through CTOD tests with three point bend specimens. The fatigue crack growth rate tests were conducted using compact tension specimens in accordance with ASTM E647. The CTOD values were affected by crack orientation with respect to the rolling direction, but orientation had no influence on the fatigue crack growth rates. The fatigue crack growth rates and the CTOD values decreased with decreasing test temperature.