February 19, 2019
Does Hydrogen Embrittlement have an impact on your industry and your company? What about your supplier, therefore, your product and your customer?
Industry standards will be changing as more information and testing works to resolve the problem of Hydrogen Embrittlement.
Hydrogen Embrittlement Definition
Hydrogen Embrittlement is a metal’s loss of ductility and reduction of load bearing capability due to the absorption of hydrogen atoms or molecules by the metal. The result of hydrogen embrittlement is that components crack and fracture at stresses less than the yield strength of the metal.
2. Hydrogen Damage Mechanism
High strength steel is broadly defined as having a tensile strength in the range of 1,000 – 2,000 MPa, (150 – 300 ksi). When high strength steel is tensile stressed, as is the case with a high strength fastener that is under tensile load from tightening, the stress causes atomic hydrogen within the steel to diffuse (move) to the location of greatest stress (e.g., at the first engaged thread or at the fillet radius under the head of a bolt). As increasingly higher concentrations of hydrogen collect at this location, steel that is normally ductile gradually becomes brittle. Eventually, the concentration of stress and hydrogen in one location causes a hydrogen induced (brittle) microcrack. The brittle microcrack continues to grow as hydrogen moves to follow the tip of the progressing crack, until the fastener is overloaded and finally ruptures. This hydrogen damage mechanism can cause the fastener….to fail at stresses that are significantly lower than the basic strength of the fastener as determined by a standard tensile test.
Hodges Fastener professionals will work with your engineering team to determine if you are impacted and help you determine what alternative options may meet your requirements. Please contact Hodges Fastener for more information and to partner for solutions.