The chemistry of embrittlement: How hydrogen dwindles cohesion in iron during fracture

Normally strong and tough, steel$\unicode{x2014}$with iron as its base$\unicode{x2014}$falls prey to severe embrittlement when infiltrated by hydrogen; the insights into why are not well understood. This work explores how hydrogen affects bond strength in iron during fracture and why it reduces cohesion between fracture surfaces, laying bare the central role of electrostatic repulsion.