Impact test for S235 JR grade

[GD_P]

For one of our steel structure project we require S235 JR grade steel. Selection of toughness grade as per EN 1993-1-10 results in JR grade. Also as per Eurocode EN 1993-1-1, even compression member require min toughness equivalent to En 1993-1-10 Table 2.1 stress category 0.25*fy. So it is mandatory that all steel grades should have min toughness.
But the parent Material Test Certificate (MTC) do not show impact test results. Supplier said that “as JR is basic grade, it is normal practice here in Europe not to show the impact results on MTC. If you purchase other grades (J0, J2 etc) you will get the impact test by default on MTC”.
So forum, what is your experience?
1) Am I wrong to request impact results on MTC?
2) Is Impact test not a mandatory requirement on MTC for JR grade? As per material parent standard EN10025-2 Cl. no. 7.3.2.2 “The impact properties of quality JR products are verified only when specified at the time of the order.” When do we specify the impact properties for JR grade?
Do share your opinion.


GD_P

 

[GD_P]

One more important point, this impact toughness is declared on DoP as per CPR. In short can we declare the toughness on DoP without impact test results on MTC for JR grade?

GD_P

 

[kingnero]

It should be on the MTC if it is of type EN 10204 3.1 or 3.2.
Lots of 2.1/2.2 certificates do not mention charpy values on JR material, whether or not it is required you would have to look up in the EN 10025-2 (?) standard.
But to be honest, it is certainly not common to declare toughness on a DoP. Weldability, yes, with the complete steen denomination (eg. EN 10025-2 S235JR+AR), but actual impact values, haven't seen that yet...

 

[desertfox]

Hi GD_P

No I don't believe you can put the impact energy values on the DoP without having the test done.

As you rightly pointed out earlier you have to state what paper work you require with the steel at the point of purchase, it cannot be supplied retrofit.
Imagine if that steel as a flaw and fails under impact, the supplier will show he didn't state the impact values on his paper work, so think were that might leave your company.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[GD_P]

Thank you kingnero & desertfox for your reply.

As per definition of JR grade, it has toughness of 27J @ 20 deg C. And still the code mention that "The impact properties of quality JR products are verified only when specified at the time of the order." Really makes no sense for me.

kingnero, you mentioned "it is certainly not common to declare toughness on a DoP".
As I mentioned in the first post that design as per Eurocode demand min toughness even for members in compression (EN 1993-1-1, clause 3.2.3 (3)B), and hence members in tension definitely require it. So members must have min toughness 27J @ 20 deg C i.e., JR is must grade.
Could you please get some insights on it.

GD_P

 

[RolMec]

As to the "only if specified" clause & some practical aspects:
All steel is to be covered by standard. But, there's the difference in importance of application / required reliability / design safety:
To order base grade S235JR without impact energy: this then is just steel for no frills utilisation, say for some odd gate, or fence posts, that is welded somehow in some backstreet shed. No MTC, no brittle fracture consideration, lowest cost.
If one designs & manufactures safety relevant structures, e.g. as per a building code, the designer mandatorily requires MTC's to the extent of the required properties AND their testing / certification level, e.g. 27 kJ @ 20°C by certificate 3.1 DIN EN 10204.


Roland Heilmann

 

[kingnero]

kingnero, you mentioned "it is certainly not common to declare toughness on a DoP".
As I mentioned in the first post that design as per Eurocode demand min toughness even for members in compression (EN 1993-1-1, clause 3.2.3 (3)B), and hence members in tension definitely require it. So members must have min toughness 27J @ 20 deg C i.e., JR is must grade.
Could you please get some insights on it.

Fist of all, are you talking about the DoP from the original producer (the steel mill) or the DoP from the fabricator who uses this steel in a construction?
If we're talking about the EN 10025-1 DoP, then yes, you'll have either generic values (eg. >= 27J @ 20°C) or the mention that it meets the specifications of the standard.
If you are looking for the actual values, you'll need a 3.x Mill Test Report (or material certificate).
A DoP is a generic document for a certain product, so as long as you produce that article, you can use the same DoP. Year afer year. Hence no actual values.

 

[GD_P]

@ RolMec,
I completely agree with you. And EN 1090 deals with load bearing structures only. So every DoP produced by fabricator as per 1090, must contain Fracture toughness characteristic. Correct if I am wrong.
Despite this, 1090 allow 2.2 certification for steel,which should be 3.1 as discussed earlier.
Sorry kingnero for the confusion, I am talking about fabricatora DoP as per 1090.

GD_P

 

[EdStainless]

Wording like this has no place in a real specification.
IF there is a requirement then you should demonstrate that it is met.
The way that I read it the supplier is responsible for meeting the minimum requirement even when they don't report it.
If I were procuring something where toughness was required I would always require reporting of actual test values.
As the purchaser that is your option.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[kingnero]

Your original question is about charpie values on MTC, now you're talking about the DoP of the fabricator.
The difference couldn't be larger.

There is no reason to put actual values on the DoP of the fabricator. If he wants, you are lucky to get the actual steel grade on it under "weldability". The construction products regulation only requires one item to be put on the DoP. Which is stupid, but that's the regulation. Also, depending on the type of DoP (1, 2, 3b, 3a). If PPCS, the fabricator should only reference the drawings of his client on the DoP.

On a 3.1 MTC, you should have actual impact values if applicable (so, not for stainless steel, but for any JR, K2, ... designated steel). On a 2.2 MTC, you'll find something along the lines of my previous reply.

 

[desertfox]

Hi GD_P

I am looking at EN10025 as I type, now basically the steel S235 JR should have the impact properties that you are quoting however if you want those values verifying then as you rightly state they need to be on the MTC.

Reading the specification further the mechanical properties can be deterioted by heat treatment like stress reliving after welding, so if the fabricator does any heat treatment on the fabrications then without further testing you cannot guarantee those impact values.
I guess this would still apply even if the impact values were on the MTC however you know what impact values you had to start with before the steel was processed.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein