Strengthening of additively manufactured tungsten by use of hydrogen in argon shielding gas

Additively manufactured tungsten was printed in atmospheres of pure argon and argon-3% hydrogen and compared on the basis of microstructure, chemical composition, and three point bend tests. The argon-3% hydrogen atmosphere refined microstructure and markedly increased flexural strength, achieving a maximum of 985 MPa. Chemical composition analysis revealed high levels of oxygen in argon-3% hydrogen parts compared to pure argon. It is proposed that the argon-3% hydrogen atmosphere aided the formation of tungsten oxides and slowed their sublimation. These oxides likely led to grain refinement by grain boundary pinning. The grain refinement produced a ribbon-like microstructure which resulted in higher strength transgranular fracture

Automated summary

Additively manufactured tungsten in atmospheres of pure argon and argon-3% hydrogen was compared and analyzed based on microstructure, chemical composition, and three-point bend tests. It was found that the argon-3% hydrogen atmosphere resulted in a refined microstructure and significantly increased flexural strength. The presence of tungsten oxides in the argon-3% hydrogen parts likely contributed to grain refinement through grain boundary pinning, leading to higher strength transgranular fracture.