Stress Relief for zinc alloy and mild steel - Diecasting process

[JHWC]

Hi,

Take a rectangular plate as an example.

Can anyone please advise me whether zinc-alloy (96% zinc + 4% aluminium) and mild steel (AISI 1020) which are made from diecasting process are require to undergo stress-relief process? Is it logical to do this?

Thanks.

 

[arunmrao]

What are you die casting in AISI 1020? Are you sure? Or have I understood your question wrongly.

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

Mahatma Gandhi.

 

[JHWC]

Hi,

Diecasting for example, a rectangular plate. Anything wrong with the sentence?

I read it somewhere that stress relief cannot be done for zinc material.

Thanks.

 

[EdStainless]

arunmarao's comment is because you don't DIE cast 1020, you may cast it, but not in steel dies.
Zn alloys are in general not heat treated. There is no benefit for most applications.
I have seen thermal cycling done on parts that needed very good long term stability.


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P.E. Metallurgy, Plymouth Tube

 

[JHWC]

Hi EdStainless,

Nice to see you again. Thanks for the input.

Do you know what is the common practice after casting? Like you mentioned, you have seen parts that underwent thermal cycling for long term stability. But is it necessary?

Thanks.

 

[metengr]

No, stress relief would be unnecessary for this application.

 

[JHWC]

many thanks metengr!

 

[JHWC]

Guys,

Thanks for the valuable input. I have a scenario here. A pulley bracket has broken into 2 pieces, probably due to brittle fracture (see attached). We found that this material is Zemak 3 and probably manufactured using die-casting process. As mentioned, this material will not undergo stress relieve since it does not bring any significant benefits.

Now, the material has been changed to mild steel and I believe the grade should be AISI 1020 or 1022. I have 2 questions here.

First, what is the appropriate casting process for this material? Would it be investment casting? sand casting? and why? How do one determine the casting process?

Second, stress relieve is usually done after casting. Other than cost saving, why some materials, for example, mild steel chose not to do stress relief? What is the baseline to do a stress relieve other than client's specification. Can someone enlighten me.

Thanks.

 

[arunmrao]

My simple question. Why cast a bracket. You can consider machining it from a plate/bar stock ( easily available). You can stress relieve the same.


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

Mahatma Gandhi.

 

[JHWC]

For mass production. Casting will be easier to adopt.

Thanks.

 

[arunmrao]

Agree. Think of any of the casting processes, depending on the size, accuracy and quantity. Finally the market economics will determine your choice.

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

Mahatma Gandhi.

 

[mrfailure]

It sounds like you think the bracket breaks from single event overload. If this is true, then you need to know the strength requirements from the design application, then you can determine whether the material (Zemak 3 or mild cast 1020-type steel) would have the strength to meet those requirements. You will need to look at other properties if you think failure did not occur from pure mechanical loading.

 

[mfgenggear]

In my opinion casting is the last method of manufacturing used. casting are difficult to maintain the same configuration from casting to casting . and is not even close to strength as rolled bar.
machining would be expensive. so maybe forged to size would be a good alternative. castings are high with problems, and a high reliability issue if not process controlled properly.