Inclusion rating in steel castings 3

[priyam07]

Hello all,

I was wondering about ASTM standard that applies to rating and classifying inclusions in steel castings.

ASTM E45 does that apply only to wrought steels or cast steels as well?

Thanks

 

[EdStainless]

Read the scope of E45.
It makes no comment about product form.

1. Scope

1.1 These test methods cover a number of recognized procedures for determining the nonmetallic inclusion content of wrought steel. Macroscopic methods include macroetch, fracture, step-down, and magnetic particle tests. Microscopic methods include five generally accepted systems of examination. In these microscopic methods, inclusions are assigned to a category based on similarities in morphology, and not necessarily on their chemical identity. Metallographic techniques that allow simple differentiation between morphologically similar inclusions are briefly discussed. While the methods are primarily intended for rating inclusions, constituents such as carbides, nitrides, carbonitrides, borides, and intermetallic phases may be rated using some of the microscopic methods. In some cases, alloys other than steels may be rated using one or more of these methods; the methods will be described in terms of their use on steels.

1.2 This practice covers procedures to perform JK-type inclusion ratings using automatic image analysis in accordance with microscopic methods A and D.

1.3 Depending on the type of steel and the properties required, either a macroscopic or a microscopic method for determining the inclusion content, or combinations of the two methods, may be found most satisfactory.

1.4 These test methods deal only with recommended test methods and nothing in them should be construed as defining or establishing limits of acceptability for any grade of steel.


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P.E. Metallurgy, Plymouth Tube

 

[priyam07]

Thanks Ed! So the ASTM E2142 using SEM is just a better way to study the inclusions in modern steel castings?

 

[tbuelna]

You should start by reviewing the relevant ASTM spec covering the specific material, foundry process, and application your casting is intended for. That document will reference any other ASTM specs that are relevant to QA of the casting product.

 

[EdStainless]

I didn't read the details but I am not sure that there is a method that allows SEM.
I have only ever seen it done optical.

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P.E. Metallurgy, Plymouth Tube

 

[dbooker630]

Clause 1.1 of ASTM E2142 reads:

"This test method covers procedures to obtain particle size distribution, chemical classification, and Test Methods E45 ratings of inclusions in steels using an automated scanning electron microscope (SEM) with X-ray analysis and automatic image analysis capabilities."

So there is a SEM method but you will have to check with your customer to see if its allowed.

 

[tbuelna]

Read the scope of E45. It makes no comment about product form.

Here's a quote from an abstract of ASTM E45-13: "4.7 These test methods are intended for use on wrought metallic structures. While a minimum level of deformation is not specified, the test methods are not suitable for use on cast structures or on lightly worked structures."

I took a quick look at an ASTM spec covering steel investment castings for pressure vessel applications (sorry, but I don't recall the exact spec number), and the section covering material cleanliness (for things like inclusions) simply stated these requirements should be based on an agreement between the vendor and the customer.

 

[EdStainless]

The bury the product form info in 4.7, I would never look that far on first pass through a spec.
Thanks for the info.

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P.E. Metallurgy, Plymouth Tube

 

[priyam07]

Thanks a lot everyone, sorry for the late reply.

As Ed said I would not go that deep looking for the scope! Thanks!

 

[mrfailure]

Star for everyone on this enlightening discussion. I did notice that the E45 Section 1.1 scope also referred to applicability for wrought products, but I probably would not have paid attention unless looking in detail for the original question.

 

[tbuelna]

sravii- Sorry we could not provide a suitable answer to your question. Unfortunately, in order to research the question you would need to first purchase a copy of the ASTM spec covering the specific type/quality of steel casting (sand, investment, etc) you are considering. Then you would need to purchase any relevant ASTM docs referenced in the first spec, and so on, and so on. By the time you're done you will have likely purchased a couple hundred dollars worth of ASTM specs and may still not have an answer to your question. The only spec that came up in a search for "inclusions" and "steel castings" on the ASTM website was ASTM A802-95, which only covers surface quality.

You can join the ASTM for $75, and I believe this would allow you to contact a member of the appropriate technical committee with your question. Probably much cheaper and faster than purchasing the specs and going thru them yourself.

Based on what I have seen with specs covering quality in most forms of cast product there is no requirement for microscopic examination. The quality specs for steel castings typically require tensile testing, chemical analysis, radiographic/penetrant/mag particle inspection, and sometimes decarb testing. However, this does not mean microscopic inspection for subsurface inclusions cannot be added as a supplementary QA requirement in addition to what is listed in the ASTM spec. Just be careful to clearly define where the test specimen should be taken from and what the acceptance criteria is. The metallurgical quality from one area to another in a single casting can vary quite a bit depending on the foundry process used. Here is a mil handbook that covers classification and soundness requirements for radiographic inspection of steel castings. The section describing different acceptance criteria for various classes/grades based on the intended application is definitely worth a read.

Hope that helps and good luck to you.
Terry

 

[priyam07]

Thanks for the detailed info tbuelna! appreciate everyone getting involved, also I will clear my hidden objective here which is to find a method to detect the inclusions using a simple method possible in the foundry (optical) and correlate to the properties. I started with ASTM E45 and started looking in to the other standards and the automated SEM inclusion analysis. I have not gotten too far with it, anyways just did not realize this it is not as easy as "use this standard" to define the cleanliness!

 

[tbuelna]

Just out of curiosity, what type of castings are you working with that require regular microscopic analysis for inclusion content? Is it something like a single crystal turbine blade casting?

You asked specifically about an optical process, and ASTM E1245-03 "Standard Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic Image Analysis" might be worth looking at. However, there is a disclaimer stating the technique is not suitable for rating exogenous type inclusions, and these are common in most casting processes. The likely reason is that exogenous inclusion content/location in a production lot of castings can vary significantly as a result of the foundry process. So checking a specimen from a given location of a single casting per lot may not provide a statistically accurate result for this requirement.

Here is a masters thesis I found that might also be of interest to you.