Tensile Armor Wires Submitted to Slow Strain Rate Tests in a Corrosive Environment and Cathodic Protection: a Comparison Between Two Different Microstructures

Abstract

Tensile armor in flexible pipes consists of two or more layers of steel wires. Damage to the outer sheath may cause ingress of seawater in the annular space and thus corrosion of the armor wires. This work focused on the susceptibility of these wires to stress corrosion cracking (SCC) and hydrogen embrittlement (HE) using a slow strain rate test (SSRT) under a bending load in an environment that contains chlorides. The behavior of two different microstructures was compared: martensite and pearlite plus ferrite. Furthermore, the materials were mechanically and metallurgically characterized. The results indicate that martensitic steel is more sensitive to both hydrogen embrittlement and stress corrosion cracking than pearlitic-ferritic steel.

Keywords

• Tensile armor
• Stress corrosion cracking
• hydrogen diffusion
• hydrogen embrittlement