Heat treatment of Steel Plates ( Plain-C)

You want to know how to normalize?

What is carbon content?

Balance of chemistry?

Why do you need to normalize, is your mill control so bad that you have inconsistent structures? Fixing mill controls will be cheaper than buying gazillions of BTU's to repair as rolled structure. What is spec for normalize that you will be controlling to?

milo

Thanks for yor respons.

We are talking about Thicker Plates 1/2 " (>12mm )and above, and rolled in Plate Mill. grades involved includes A516 Gr 70 , A572 Gr 60 , API2H, etc . Heat treatment are required asper specificaton in such thickness .

Chemistry : with C varying 0.12 - 0.25% , Mn : 0.80 - 1.6 % , S& P0.015max, % Si : 0.15/0.25 , % Al: 0.02- 0.06 % (optional)

also , where ever required - it is Microalloyed with V & Nb as well .

SK Hegde

Actually, no heat treatment is required for ASTM A 572; just conformance to mechanical properties; heat treatment and normalized are terms that do not appear in this spec. nor in its keywords listing. The high strength low alloy boost that columbium and vanadium add to this steel make cooling rates extremely important.

Moving on.

ASTM A 516

5. Heat Treatment

5.1 Plates 1.50 in. [40mm] and under in thickness are normally supplied in the as-rolled condition. The plates may be ordered normalized or stress relieved or both.

5.2 Plates over 1.50 inches [40 mm] in thickness shall be normalized.

etc. etc.

Another KEY Question: Are all your melts fully killed steels?

milo

Thanks .

Originally our discussion was aimed at finding a suitable "Roller hearth type normalising/heat treatment furnace ". Wnated soem one in the field to suggest suitable furance , heat treatment like quenched & tempered steel plate production .

Yes , A572 is a microalloyed steel, does not require HT but cotrolled rolling .

However , A516 Gr 70 , A517 Cl1 , etc are some steels we are looking for normalsiing , Q&T , etc applications . Thus , from this forum , wanted some designer/supplier of Heat Treatment furnace to comment /write on above.

The big issue will be atmosphere control so that you don't decarburise, nor recarburize the surface. also, controlling time in zones and number of zones to assure uniform heating and cool down profile. with these steels, location of the furnace will be critical as 'colling in stil air" is a part and parcel of normalization process. Radiation to a clear sky, precipitation, drafts and or wind through neighboring doors and or cooling fans can destroy the best controlled furnace prep work.

Find out how they are going to control the atmosphere- endo thermic or exothermic and make sure you understand the consequences beyond ca$h.

I can only imagine what a plate Q&T line might look like. I'm impressed.

milo

Please tell the plates dimensions,

If the plain C steel is high C steel, you please heat at 880 C and then cool with fan. or forced air, it will be normalized.

Please see my post 5 above. Fans will not result in a uniform normalized product. Fans will result in localized cooling rates and differences in structure.

880c is a compromise temperature, and will suffice for most medium and higher carbon steels.

low carbon steels will need to be above 926 C to achieve full normalized structure.

milo