Microalloyed steel bainite in microstructure

[Liuk]

Dear colleagues,

Could you give me any advice about evaluation of microstructure of steel 38MnVS6.

Only ferritic-perlitic structure is acceptable.

If sample 2 microstructure consists from ferrite and perlite (+sorbite?) microstructure of sample 1 consists from ferrite, perlite, bainite (lower?) and martensite. It is my opinion, but I have very small experience in microstructure of this steel...

Please let me know your opinion.

Thank you in advance

 

[Liuk]

I can't attach 2 photos. Sample No 2.

 

[metengr]

Your sample #2 microstructure looks like a dual-phase steel consisting of ferrite and fine and coarse pearlite. Your sample #1 has other transformation products besides ferrite and pearlite, and is not a dual-phase steel.

 

[MetalHead83]

I agree with metenger.
The company I work for makes this grade on a fairly regular basis, and sample 1 does appear to have bainite. I wouldn't commit to martensite from a black and white micro-photo, but the wider streaks all running in one direction look suspiciously like it. Especially if they appear gold-ish after a picral etch, which this appears to be.

Out of curiosity, what is the application? I know 38MnVS6 is typically for bolts and the chem is designed so that there is no 'need' for heat-treating after rolling...

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