410 hardness as per NACE

[chonghm]

hi,

Currently I'm developing 2 procedures. 1 is 625 overlay on Stainless steel 410 and the other is a closure joint of 410 to 410.

May I know what's the hardness requirement as per NACE? I could never seem to get the hardness as per NACE requirement of maximum 250 HV10.

For F6Nm, there's a paper that says that the maximum allowable hardness is at 275HV10. Since 410 is also martensitic stainless steel like F6Nm, can I use the maximum allowable as 275HV10?

 

[Dhurjati Sen]

Dear chonghm,

MR0175 specifies 22 HRC for SS 410. You cannot go above that.

Regards.

DHURJATI SEN

 

[remetaper]

Chonghm, 410 has a tempered martensitic structure. F6NM shows a tempered martensitic structure with a certain amount of stable austenite depending on its chemical balance and tempering temperature. This kind of austenite is a good "airbag " in some aggressive and cryogenic environments.
This may be the reason why a higher hardness is permitted by NACE when compared to 410 grade. F6NM ( alias EN 1. 4313 )thanks to its structure offers a better general corrosion + H embrittlemnet resistance for sour gas applications and higher Kv values.
In

http://www.valbruna-stainless-steel.com,

you can find a easy and short description about the metallurgical behavior of this soft-martensitic SS ( find in martensitic grade X134M or in technical article about soft-martensitic). Little survival kit in order to undestand these grades.I hope this addition could help you.

 

[EdStainless]

410 is a odd animal. Some is truly martenisitic, and some has such low C that it is in between M and F. You need to know the C and prior HT in order to know what you are working with.
We used to make a fair amount of 410 tubing and we would take a sample and record the as-quenched hardness. It gave us a good idea of what we were working with.

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P.E. Metallurgy, Plymouth Tube

 

EdS,
The Schaeffler diagram indicates 410 is martensitic-ferritic, but different heat treatment conditions give a wide range of mechanical properties.
F6NM, or any 410NiMo (13Cr-4Ni) type, is an exception from the other martensitic grades in terms of heat treat condition, PWHT temperature, and welding preheat temperature. It can be heat treated to produce acceptable NACE hardness, with better fracture toughness than 410. In both alloys, ferrite is a bad actor for toughness. Weldability of 13Cr-4Ni is better than 410, especially with matching filler metals - 410 filler is prone to solidification cracking.
13Cr-4Ni also has the unique property of being fully air hardenable to essentially unlimited thickness. Note that it has a different Group no. in Section IX.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[EdStainless]

I believe that 410 has a C range of 0.08-0.15% (this is from memory).
At the low end it will not Q&T at all, at the high end it is martensitic.

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P.E. Metallurgy, Plymouth Tube

 

EdS,
410S, with max. 0.08%C, is a ferritic SS.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[Metaldoctor]

410 per NACE needs to be Rc 22 max, and also needs to be quenched and double tempered to be in compliance to NACE. Be careful not to go higher that the first tempering temperature when you set up the stress relief of your 625 weld, or you will likely degrade the base metal 410 properties. I have seen some specs that require a first temper restriction of 1200 F min to facilitate a weld stress relief cycle just under the 1200F.