Pitting corrosion steel plates

Toughness is as noted, a measure of how well a material can absorb energy without fracture.

One can use the area under the stress-strain curve as a means of identifying “better” materials, if one wishes, but it is really the volumetric attributes, not the area per se. Energy is a volumetric property. Some also use the ratio between UTS and yield as an approximate indication, in a manner which I also referenced, in terms of “safety” margins. Thus the amount of strain to fracture and we get the Charpy or Izod means for testing.

But the toughness of say A grade steel with an elongation of 22%, is very different from that of E grade steel, which also has an elongation of 22%. Yet the A grade is a measure at 20c, whereas E grade must be at -40c.
Steel's toughness has a wide range.

Whereas aluminium, exhibits a very flat “curve” of toughness, down to around -200c, no matter what temper is selected. Thus not influenced by the elongation to failure/fracture.

 

Picture

I have uploded the picture

 

I'm not seeing the photo in the above post -- can you re-save the photo as a jpg before uploading.

 

There are below grades in our shipyard:
A B D E AH32

 

I try to upload the photo and it gets 100% but it does not attach well.

 

Try resizing the photo down in resolution to say 1000 pixels across and then re-saving / exporting as a new jpeg format image.

 

There are below steel grades in our shipyard with pitting:
A B D E AH32

 

I could not attach the picture.
It is belt grinder PASOVEC75

 

I want to send the picture in pdf format but i could not why?

 

What is the filesize of the pdf? Is it a drawing where the pdf has an advantage of keeping lines vector?
If it's a photo, try saving it as a jpg instead; or you could upload your PDF to another web space and provide a link instead.

 

Belt grinding machine

 

The file size is 0.5mb jpg.

 

For those interested, these links offer a relatively simplified explanation of (1) mechanical properties, (2) heat treatment processes (though missing some more complicated heat treating processes but whose alloys would probably not be
found in shipbuilding steel) , carbon percentages of various steels noted above and (3) an article describing why common low carbon steels commonly used in shipbuilding cannot be heat treated

1) Mechanical Properties of Materials | MechaniCalc https://mechanicalc.com/reference/mechanical-properties-of-materials

2) https://www.reliance- foundry.com/blog/steelgrades#:~:text=For%20example%2C%20'A'%20indicates,assigned%20to%20galvanized%20carbon%20steel.&text=Tensile%20Strength%2C%20UTS%3A%20330%20MPa,or%2035%2C000%20psi%20(Grade%20B)
If this rather long address does not work, try reliancefoundary.com and it may take you here

3) Buy Steelonline from Steeloncall-India's Leading Steel marketplace for construction and building steel products at low prices in india, Faster Delivery Guaranteed. https://steeloncall.com/why-can-t-low-carbon-steel-be-heat-treated

The OP listed alloys, A, B, C, D These steel alloys have an advertised low carbon content below .3% and with normal heating and quench are not heat treatable. Meaning that heat generated due to grinding will not change the steels
properties.
The OP's inclusion of AH32 introduces a slightly higher carbon content of .4% which can be heated and then quenched (quenched being a fast immersion in water or oil to reduce the heat reduction time and create Martensitic grains)
As heat ( to over 1500 degrees) and quench process would not occur in grinding or milling, this alloy would be fine to grind as well.

Certainly, the introduction of carbon,boron, nitride or boride in contact with a hot low carbon steel, ie heating in the presence of these (or other elements) SURFACE with a subsequent quench Might produce case hardening, the very thin surface can be slightly hardened.

 

I looked up the above mentioned belt grinder. Not what I thought. Sure it makes sparks, lots of noise, and consumes power, But I think you will be wasting your time, tediously doing laps very slowly, making plates with undulating topography and very variable thickness. It looks like a dry grinder, with no cooling or flushing, (you'd probably get wet). Be aware that buildups of steel and iron dust, grindings, and fine swarf can catch fire and burn if dry, ignited by the sparks. I hope your grinding belts needed for it are extremely long lasting, super efficient, local and cheap, and you have free solar power. See how it goes on your worst plate both sides, cost labour plus consumables and other expenses for it, multiply by your stack of plates, and see how you feel afterward. Cost/benefit includes your time and patience and sanity, and that of your workers. Don't bother with your thinnest plates.
At 12m x 2.4m, and down 2 mm both sides, I estimate at least 1 week of full time work grinding per plate, and worker attrition. It could end up being very expensive plate. Please let us know how you go with it. I for one am interested in how your grinder goes on just one plate. Best of luck with your task.