Sheared bolt

[vyv_cox]

Vyv. Thanks very much. What does “sintered” mean?
And for a non expert like me, is this simply over tightened (by a wimp like me) or is there a likelihood that it was a faulty stud?

As others have said, sintered components are made from powdered metal. The implication in these posts is that these components are cheap and nasty but this is not the case. There are some alloys that cannot be made in any other way, for example some aero engine blades. Accuracy of compositional metals is very high with little variation through the component. Good quality sintering produces items with porosity levels of not much more than 5%, better than some castings.

I think over-tightening is a possibility, although a sintered stud, if that is what it is, should be as strong as a wrought one

 

[vyv_cox]

Very much a shot in the dark, and I defer to @vyv_cox ! But assuming the colour on the first photo is right, it looks very like copper oxide, not copper metal.

I agree, and my first thought was dezincification, which would produce porous copper that could subsequently oxidise. The problem with this is that there is no gradation of appearance across the faces which cannot happen with that mechanism.

 

[dunedin]

I agree, and my first thought was dezincification, which would produce porous copper that could subsequently oxidise. The problem with this is that there is no gradation of appearance across the faces which cannot happen with that mechanism.

The component is brand new, being fitted for the first time, so assume not dezincification.

 

[dunedin]

You could ask Robert Desadler 07799143888. He's based at Lerags south of Oban but travels in the area. He deals with boat engines and electrics but has been talking of retirement.

Thanks- just too late to do that, taken south on the train

 

[AntarcticPilot]

The component is brand new, being fitted for the first time, so assume not dezincification.

Then in that case I'd suspect a pre-existing flaw.

 

[Neeves]

As others have said, sintered components are made from powdered metal. The implication in these posts is that these components are cheap and nasty but this is not the case. There are some alloys that cannot be made in any other way, for example some aero engine blades. Accuracy of compositional metals is very high with little variation through the component. Good quality sintering produces items with porosity levels of not much more than 5%, better than some castings.

I think over-tightening is a possibility, although a sintered stud, if that is what it is, should be as strong as a wrought one

There was a company in the UK, Manganese Bronze, I think that was built round power metallurgy - but they may have been assimilated. They were part of the group that also built the London Taxi, decades ago. If you have earthing plates for a SSB - they are made using powder metallurgy but with a focus on increasing surface area (and thus porosity).

Jonathan