Delayed fractures

Delayed fractures occurs screws break just in the zone were cover and base material connect. There can be several causes for this effect:

• Hydrogen embrittlement: hydrogen released during electrolytic coating processes, can be occluded in the screw, critically so in parts with high hardness and under high tensions. Optimizing hardness, tightening or baking the parts could reduce this effect. Breaks could happen hours or days after assembly.

• Corrosion stress cracking: parts under highly corrosive environments could generate fractures due to material loss or to induced hydrogen embrittlement. Breaks usually take months to occur.

• Load fractures: external loads applied to the assembly could elongate the screw beyond its strength limits. Also, these loads could separate cover and base parts, transmitting tensions and bending stresses which could break the parts.

Contact our technical department if you have any question on that matter and we'll provide you a solution.