Re: [MW:32105] Impact energy Vs Structure

Greetings

When carbon steel (BCC) - cools rapidly it forms BCT -martensite .

When Austenitic Stainless steel (FCC) - Rapid cool may form FCT martensite . Based on CCT AND TTT diagrams.

Regards

Vinoth kanna

9787954338

On Sat, 27 Mar 2021, 11:05 sunil kaushik, <sunilkaushik08@gmail.com> wrote:

What is the difference between BCT and FCT structure?

On Thu, 25 Mar, 2021, 9:29 am Vinoth kanna ramachandran, <srvkanna1@gmail.com> wrote:
Dear sir,

Greetings for the day

Mild steel - BCC structure (body centred cubic )
Austenite stainless steel - FCC structure (face centered cubic)
Martensite - FCT structure ( face centred tetragonal )

coarse grain means - less FCT crystals , fine grain means - More FCT crystals.

Tetragonal structure can't absorb more impact energy , due to its crystal structure , since it prevents its movement . if it's fine grain , still more difficulty to absorb energy .

That's why FCC crystals have better impact properties than any other in the steel family .Fine Grain FCC - greater impact energy absorption.

Regards

Vinoth kanna
QC- welding & piping inspector
Manifa Project

API -510, CSWIP 3.1, NDT level II - UT, RT ,PT, MT, VT,LT,Infrared & Thermography
Technical - Metallurgy

Contact : M - +91-9787954338,+966-539127946
Email id : srvkanna1@gmail.com

On Thu, Mar 25, 2021 at 8:43 AM EmaD FaRaHanI <emad.farahani@gmail.com> wrote:
Dear Friends,
Consider we have a mild-steel, cooling fast from welding temperature, we must have a fine grain structure with martensite formation.
Hypothetically, considering that we want to use this structure. I was wondering what is the relation between the impact energy and the structure? will it be decreased due to martensite formation? or increased due to fine grain? I understand that we don't use the martensite state of structures and we need to quench and tempering them.

Thanks,
Emad

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