Influences of hydrogen and textural anisotropy on the microstructure and mechanical properties of duplex stainless steel at high strain rate (~10⁵ s⁻¹)

Abstract

Duplex stainless steels (DSS) have exceptional mechanical properties, such as high strength and ductility, and are commonly used for pressure vessels and underwater pipelines. One of the main problems experienced in maximizing DSS service life is their interaction with hydrogen. Hydrogen, which is common to most manufacturing processes and services, can lead to the deleterious effect known as hydrogen embrittlement. The susceptibility of steels to hydrogen failure is directly related to hydrogen’s interaction with steel’s defects (traps), and therefore grain texture can have a major influence on the trapping phenomenon. The purpose of this study is to analyze the influences of hydrogen and textural anisotropy on DSS mechanical properties at high strain rate (~10⁵ s⁻¹). This includes the influence of hydrogen on crystallographically isotropic (equiaxed grains) and in crystallographically anisotropic (elongated grains) DSS on dynamic properties. The simulation of DSS exposed to explosions during extreme conditions of failure was performed by planar shock wave experiments at a very high pressure (~19 GPa). The great importance of these experiments is their ability to change the plasticity and deformation mechanism of the metal, and therefore, provide new insights into hydrogen behavior at high deformation levels. The effect of grain texture on dynamic properties was shown to play an important role in the elastic–plastic response at high strain rate. This phenomenon repeats itself when hydrogen is involved in the process. It was shown that the susceptibility to hydrogen embrittlement decreases at very high pressures ≤8 GPa for elongated grains and ≤19 GPa for equiaxed grains.