Hardness Value for SA335 304H, SA312 304H and SA403M WP304H 1

[replica]

Hi all,

Any idea on why the hardness values for the SA335 304H, SA312 304H and SA403M WP304H stainless steel and most of the stainless steels are not mentioned in the specification? The hardness for stainless steel is only specified in SA231 tubes. Can we take minimum tensile strength in stainless steel and convert them to hardness as the reference minimum hardness? or can we use the hardness values in SA213 as a reference for any other class of stainless steel?

Comments are welcome....

Happy New Year to all...

 

[Dhurjati Sen]

Check NACE MR 0175. You need to have the UNS number of the desired SS. You will get maximum hardness values.

DHURJATI SEN

 

[replica]

Dhurjati Sen

Thank you very much for the information, but this is for H2S environment. What about for the other applications.

 

[mrfailure]

It is not valid to convert between tensile strength and hardness for austenitic steels like 304H. Tensile/hardness conversions listed in ASTM A370 only apply to ferritic steels and also should be considered approximations.

 

[EdStainless]

The tube specs do have max hardness, most are HRB 90.
It is usually listed in the tensile table in the spec.

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P.E. Metallurgy, consulting work welcomed

 

[replica]

mrfailure
It is not valid to convert between tensile strength and hardness for austenitic steels like 304H. Tensile/hardness conversions listed in ASTM A370 only apply to ferritic steels and also should be considered approximations.

Yes I am aware about this and all this while only used it for ferritic steel

EdStainless
The tube specs do have max hardness, most are HRB 90.
It is usually listed in the tensile table in the spec.

Thank you EdStainless. But this in only for SA213 304H (tubes) and not stated in SA335 304H, SA312 304H and SA403M WP304H and others ...Can I use SA213 304H of 200HV (90HRB or 192 HB)as a reference hardness for others? I mean if there are not for H2S environment. The other issue is where do you get the reference for the acceptable hardness for the weldment of SS304?..I mean base metal and weld deposit.

 

[EdStainless]

Any annealed product in these grades should be able to meet the max hardness of the tubinging spec.
As welded will be harder. I have seen some people use HRB100, but I have also seen other higher numbers as well.
There will be no increase in base metal or HAZ hardness.

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P.E. Metallurgy, consulting work welcomed

 

[mfgenggear]

run test samples and actually verify hardness. hardness is used for mfg as a reference,

 

[replica]

EdStainless...Thank you... I have seen the hardness as high as 260HV for 304H in the presence of slip bands due to cold working. What is the the purpose of stating the maximum hardness in stainless steel tubes as in SA213? Should the values above 90HRB what is the effect on the material and should it be rejected?


mfgenggear
run test samples and actually verify hardness. hardness is used for mfg as a reference,
Thank you....Can you clarify further on this because I could not get it..

 

[EdStainless]

SA213 material should be annealed and any and every location should meet the max hardness limit.
Yes it is grounds for rejection.
Strain hardened material will have lower ductility, be more prone to SCC, and may have other issues.

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P.E. Metallurgy, consulting work welcomed

 

[replica]

SA213 material should be annealed and any and every location should meet the max hardness limit.
Yes it is grounds for rejection.
Strain hardened material will have lower ductility, be more prone to SCC, and may have other issues.

Thank you EdStainless.

 

Bulk hardness of 300 series steels is not of much practical interest, and it is generally not possible to differentiate these materials by hardness testing. Values are typically well below ASTM limits. NACE MR0175 is one place where it is relevant.

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

 

[mfgenggear]

any material is purchase to a specification, and that material must meet the requirements.
300 SS is also machined as bar and other wrought material. harness is important for machining feeds and speeds.
annealed steel sheet is important for forming , 300 series can be 1/4. 1/2 & full hard.

Replica
take actual tensile test & Rockwell hardness samples to verify it was processes correctly to the specification.

 

[replica]

Bulk hardness of 300 series steels is not of much practical interest, and it is generally not possible to differentiate these materials by hardness testing. Values are typically well below ASTM limits. NACE MR0175 is one place where it is relevant.

ironic metallurgist . Thank you for the comments.

any material is purchase to a specification, and that material must meet the requirements.
300 SS is also machined as bar and other wrought material. harness is important for machining feeds and speeds.
annealed steel sheet is important for forming , 300 series can be 1/4. 1/2 & full hard.


take actual tensile test & Rockwell hardness samples to verify it was processes correctly to the specification.
mfgenggear ..Thank you for the suggestion.

 

[EdStainless]

As an aside:
We had a set of sample that were different grades of 300 SS and with various amounts of cold work.
We then tested these ourselves on five different hardness scales and pulled 3 tensiles each.
These were the corrections that we used in house for process applications.
In annealed 300SS the hardness only has a very loose correlation to strength (you statistics prof would shoot you for relying on it) and this gets better as the cold work and strength increase.
Often it is the elongation that is the most sensitive to composition, annealing, and cold work. Again we had in house elong limits for various alloys and conditions (for example annealed 304L/316L >50%) that we used. This is tricky though because the reported elong will depend on the sample size/shape and strain rate (these alloys are very strain rate sensitive).

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P.E. Metallurgy, consulting work welcomed