Interactions Between Peened Surfaces and Solute Hydrogen in Steels

Author:  School of Materials Engineering, Purdue University
Source:  The Shot Peener magazine, Vol 38, Issue 3, Summer 2024
Doc ID:  2024021
Year of Publication:  2024
Abstract:  
ABSTRACT Once a peened surface is placed in service, the interaction with the environment can alter the state of the material. This paper demonstrates how hydrogen, a common element which can dissolve into many metallic systems, can decrease the compressive residual stress in shot-peened steels. INTRODUCTION Solute hydrogen in steels can dramatically reduce the toughness of the material. Hydrogen embrittlement is a perennial problem for steels in corrosive environments where the hydrogen uptake is driven by electrochemical corrosion reactions. In these cases, the contact with hydrogen is often not desired but unavoidable. With the increased interest in de-carbonizing power systems, there is added opportunities for situations where hydrogen gas will be in contact with steels as an energy carrier for power generation, via fuel cells or combustion where contact with hydrogen is part of the design. The decomposition of H2 to H, which may occur during combustion processes, provides yet another pathway for dissolving atomic H into steel. In either planned or unavoidable scenarios, dissolving H into the steel requires both entry and subsequent diffusion into the alloy. When in the steel, H can be mobile or trapped to features such as precipitates, grain boundaries, or dislocations.