×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Antimony in heat resistant steel castings

Antimony in heat resistant steel castings

Antimony in heat resistant steel castings

(OP)
I want to ask you for your opinions regarding antimony influence to heat resistant steel castings. We found antimony content from 0.05 % to 0.1 % (in extremely cases) in two our materials (1 austenitic, 1 ferritic). Fero-niobium (columbium) is suspected as a source (investigation is still in progress).

How detrimental could be effect of antimony up-to 0.1 % to this kind of steels?

In these two steels we have problems with tensile strength, yield strength and elongation (at 20 deg. C) as well.

RE: Antimony in heat resistant steel castings

What is the service and how are your mechanical/corrosion tests?

If any problems were to occur I would envisage this would be with the ferritic due to embrittlement and subsequent cracking. What grades are they?

RE: Antimony in heat resistant steel castings

(OP)
They are vane rings or discs in turbocharger assemblies. Corrosion test were not carried out.

Mechanical properties of ferritic casting: Rm 290 MPa (shall be 450 MPa), Rp0,2 unmeasurable (shall be 400 MPa). Elongation unmeasurable (shall be 5 %). The fracture was very brittle.

Grades are special, ferritic is 1.4740 + W + Nb, austenitic is chromium-manganese heat resistant steel.

RE: Antimony in heat resistant steel castings

Antimony is a bad element when it comes to steels. It will segregate at grain boundaries at elevated temperature and cause embrittlement.

RE: Antimony in heat resistant steel castings

How was the melt charge prepared? Any suspect scrap or metal? Your suspicion of Ferro Niobium to be containing Antimony,may be correct.

But, I wonder then the content of Antimony in Ferro Niobium for you to record 0.05-0.1%. As metengr states, I agree, Antimony is not a friendly element.


"Even,if you are a minority of one, truth is the truth."

Mahatma Gandhi.

RE: Antimony in heat resistant steel castings

Can you describe the fracture surface? Did it look shiny? Did it look dull? Did it sparkle in the light? Was there any necking whatsoever?

Do you have a lab with an SEM? If you can determine that the fracture was intergranular, then that would support Sb segregation to grain boundaries.

RE: Antimony in heat resistant steel castings

Did you conduct long term aging at high temp before you did the corrosion test?
I suspect that hot properties, and long term properties will both suffer.

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

RE: Antimony in heat resistant steel castings

(OP)
@metengr, definitely ferro-niobium, because antimony content is correlating with niobium content... spectral lines were checked by specialist, it is not an influence of niobium spectrum, but real antimony content... it looks like we have antimony content higher for a while in all our alloys which are alloyed with ferro-niobium (firstly the measured antimony content 0.05 % max. was considered as a measurement error)...

@winstonsk: fracture brittle, shiny, sparkle in the light, no necking, SEM in external lab can be carried out for information, but after investigation of antimony sources and their rejection

@ed: no aging and corrosions tests, they are not required by customer standard or customer is doing it by himself

Anyway, this is big issue. As all of you wrote it looks like there will be a lot of troubles during service in VTG.

RE: Antimony in heat resistant steel castings

Is Your heat of steel produce by a known/reputable vendor... or was it produced by a lesser-known vendor... or perhaps imported from a third-world source... or a less reliable Chinese source?

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true.
o For those who believe, no proof is required; for those who cannot believe, no proof is possible.
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion"]
o Learn the rules like a pro, so you can break them like an artist. [Picasso]

RE: Antimony in heat resistant steel castings

Ouch. It sounds like you have sent some finished product into the market? I think a recall would be less expensive than the potential damage - financial and reputation.

je suis charlie

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources