Guest Editorial -For Plateworld.com
Don Baudrand, Don Baudrand Consulting, e-mail:email@example.com
Don's Theory of Hydrogen Embrittlement of Steel alloys
Metal alloys form crystals. (All metals do this) Without hydrogen the bond strength between crystals of metals or alloys is quite strong. With hydrogen present atoms of Hydrogen find their way to the crystal boundaries. (Why? See below) The rate and concentration of hydrogen’s movement is determined by stress and/or strain that allows faster migration to these areas. Corrosion in the vicinity generates additional hydrogen and causes earlier failure or fracture.
How much hydrogen is too much? Since hydrogen migrates and is drawn to stress areas, it takes very little hydrogen to cause failure if the item or part of it is subject to stress. The higher the stress the faster the hydrogen finds its way between the boundaries under the most stress, weakening the adhesive bond between crystals and leads to failure.
Why are alloys more susceptible to stress failure? Possible because the crystal boundaries are weaker than for pure metals.
Dons Theory: Why does hydrogen act this way? I think that hydrogen, as an
atom (H), needs to have another electron to satisfy its only orbit This great
desire causes two hydrogen atoms to get together to share the second electron
(H2) partially satisfying the need for 2 electrons. When hydrogen is delivered
to a metal alloy the metal can offer an
electron. In stressed areas there are more electrons available to attract hydrogen to the crystal boundaries.