Manganese (Hadfield) steel precipitation when welding?

[kingnero]

When welding large hadfield castings, several months later we encounter cracking and chipping (loss of material) in/near the weld zone.
Situation: Hadfield castings, loaded in severe shock loads.
Repair weld of worn zones by a butter layer of 307, followed by welding of high-manganese elektrode (same material as base material) (both SMAW).
grinding before welding, followed by dye testing.
Trying to keep interpass temps below 200 C (400 F).

Any ideas what the aligned black lines are you can see in the grains? is that already carbide precipitation?

Picture is upside down: top part is base material (Hadfield), below you'll see first layer of 307.

PS this has already been briefly discussed here: thread 329658

any other ideas about above picture or ideas/suggestions about welding Hadfield castings?

 

[Venturini]

The parallel lines inside the grains are clivage lines due to cold work or retained stress action in the austenite grains.

 

[kingnero]

would it be possible to get these lines from heating/shrinking actions (when you say retained stress...) due to welding?

I will check the test piece again to see to which distance from the fusion line these paraller lines occur.

 

[metengr]

These are unrelated to welding. They are slip lines within the grains associated with work hardening.

 

[Venturini]

I'm sorry, a co-worker alerted me that I mistranslated it.

Those lines are called deformation twin bands in english.

It can be formed close to the weld due to thermal stresses. It's hard to say without further information if its due it because those can be formed during solidification or heat treatment as well.

 

[arunmrao]

What is the carbon content in your welding electrode? You seem to have taken necessary precautions. Reclaiming wear parts by weld repair has not been very successful in my experience. A few times the results are encouraging and other times disastrous.
I am unable to view the picture to offer any comment.

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year

 

[kingnero]

butter elektrode (first layer only):
typical : .07 % C - 18% Cr - 8% Ni - 6%Mn - .85% Si - low levels of P and S

picture attached again.

 

[kingnero]

arunmrao,
would you still care to comment?

 

[arunmrao]

kingnero, Thanks, I do not have much to comment ,due to paucity of details . However thee a few other issues I might share,if you care to connect. You can find me on LI ET forum .

I am battling with a customer for breakage of 2 toggle plates . Castings are good ,no internal defects and the material is cast iron.Any reasons, you may suggest?

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year

 

[Guest102023]

Given the high work hardening rate of Hadfield's, the deformation twins are unsurprising. They should not cause concern and have nothing to do with sensitization.

 

[EdStainless]

The grain boundaries worry me more than the twins.
Why the 307?
If you are overlaying with matching chemistry the 307 will just form a layer with much different thermal expansion.
How do railroads repair crossings and switch frogs? They weld on Mn steel castings all of the time.

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[arunmrao]

Ed,the casting being discussed are the rail road castings. These are not heavy mineral processing castings. I agree with your comment on 307 ,also I suspect the selection of Manganese steel electrode.

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year

 

[EdStainless]

Thanks, when they said very large I thought mining. RR is all medium sized stuff to me.


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[kingnero]

I didn't say very large, I said large, as in up to 8m in length. everything is relative, it appears, as where I used to work their biggest castings were measured in mm's. So this is large to me.

Nevertheless, I appreciate your comments.
Different thermal expansion coëfficiënts do not really matter as the delta temp is limited to 50-60 degrees C at most, and since they're both austenitic of nature, the difference isn't that big.

What is the matter with the grain boundaries?

 

[metengr]

In these types of steels, carbon precipitation will ocurr along grain boundaries and result in low toughness or embrittlement. These must be welded with no preheat, low interpass temperatures, low heat input and fast cooled.

 

[Screwman1]

Normally when I have seen these welded it has been in the field with a grind back for prep and then the welder turned the amperage up about as far as it would go so he could burn as many rods as possible in the limited window that he had to weld while the track was shut down. It was all pretty crude.

 

[EdStainless]

Yes they used high current, but also very high deposition rates so that the actual heat input was not too high.
I think that the grind back for prep is critical.

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