grinding welds

Your statement defining what is an elastic property, was correct, the statement only.

Your understanding of this statement, is incorrect. Hence you're confusion of what you say and what you actually understand:

I assume you're not a naval architect or structural engineer. Since to make a statement that steel is very elastic clearly suggets you may able to repeat/quote a definition (from memory or a text book), but lack its understanding. No engineer would say that steel is very elastic.

 

Your definition of elastic please.

 

Ho hum

Mike disagrees with me and then uses different terms to say the same thing.
Ad Hoc has a problem with reading.
So I think I will let this discussion on my part rest.

Bye bye

 

Frosty as I'm sure you know, Hooke's law is the practical applicable definition of elasticity for engineering materials.

 

Then the language I'm using is apparently not the language you use.

You'd have the same experience trying to express yourself to any of us apparently dyslexic engineering types. But oddly... we generally understand each other quite well, at least at work

 

grinding your welds

pros and cons
painting on a unground weld if the slag is not fully removed the paint cant adhere to it good when i made the steel work for the motor rooms on the boats we only grind the welds they get in the way of other things mounting smoothly but on the outside of hulls as most ppl no just becus its not a racing boat this don't mean that on the long run having it as smooth and streamline as it can be over all this helps cut fuel cost makes a nicer paint job plus the Les resistance the water has to pas over the welded spot the longer the paint last
above the water line is more for aesthetics as this is not going help in the streamlining of the hulls the in portent thing is don't grind away your hull its self you need to be a good grinder for a good job of it no digging in making edging waves and such best thing do for grind your welds is spay a cheap latex primer on it so you see what your rely doing

 

Im quite a way from a library, could you-- you know just run it through for me --the basics like what is Hookes law?

 

You're already online - how hard can it be to Google "hookes law"?!?!?

 

Poida et al

Let's kindly assume that Poida's use of the word "very" was a loose one and have done with it. Steel does have elasticity, you both already agree, and it is a property that makes it useful in ships and boats.

Getting back to the point of grinding welds, on a more practical front - OK, so you realize you've over-ground a joint. What's the remedy?

Will it return things back to normal if you re-weld it? Or are you completely screwed and have to cut out the area and put in more "fresh" metal?

 

Ray,

It all depends.

It depends upon the amount taken out and the resulting shape that is left as well as the location of the weldment. Coupled with the expected loads during its service-life.

The answer to these shall dictate the remedial action, if any.

 

The stiffer the material is the more useful it is structurally. Elasticity leads to structural instability and it's undesirable.
Look up Specific Modulus and Elastic instability and you'll get an idea of why elasticity is not good in structural materials. What you really want is stiffness.

The stiffer the material is for a given strength and mass the lighter the structure you can build from it.

 

So why not build boats out of ceramics then?

 

Because they are brittle.

Stress concentrations in material (or joints), are relieved by permanent deformation, or "flow". If a material flows easily crack propogation is very difficult, and thus the material is considered ductile. If the flow is difficult crack propogation is easy, thus the material is brittle.

Ceramics are hard and brittle at room temperature. Their lack of 'slip system' for deformation makes them impossible to use for boats. You wouldn't be able to bend it into a hull shape for starters!

 

Toughness

 

C'mon man, I'm just trying to bring some balance to the conversation. The previous poster mentioned that ships flex under stress (paraphrasing). I think his point was that if they didn't, they would break. Isn't that so? Surely the elasticity in steel is a useful property that makes it a great material for boatbuilding?

On his point, I think you have to give a little and not be so pedantic.