Brass rods micro-structure effect on forged parts quality 2

[SahandSM]

we produce brass rods and recently have received a quality complaint from a forging customer.
we have delivered two different batches to the customer. the customer is satisfied with the first batch, while complains about the second batch.

the chemical composition of both batches are similar.

Customer has forged all the delivered materials to products and there are no intact rods to be evaluated.
So, we only have access to forged products. (we should have kept our original samples for longer)

metallography of two sample products produced from two batched shows considerable differences.

micro-structure of the sample product from the first batch is homogeneous.

micro-structure of the sample product from the second batch is dendritic.

the average hardness for the first sample is 94.7 (HBW) and for the second sample it is 101.2 (HBW). (in our opinion these are both in range)

while my perception is that the second batch we have delivered to the customer were probably faulty, our engineer reasons differently.
He believes the difference in micro-structure has been caused during the forging process.
He even further reasons that even if the brass rods micro-structure were not homogeneous in the first place, it should have turned to homogeneous via re-crystallization if the parts were forged in correct temperature. Hence, he concludes the forging temperature and process for the two products were not stable and identical while the customer claims they were.

we are trying to recall parts of the same batch from another customer. (we have provided another customer from the same batch and they had no complain about the product).

Meanwhile, just to help me learn more about this, could you please comment on below points as general questions:
1- Do you believe the micro-structure demonstrated in the second picture can cause problems in forging process? (assuming the same micro-structure is valid for the rods before forging)
2- Do you believe a non-homogeneous micro-structure can be corrected during the forging process by choosing the right temperature leading to re-crystallization?

thank you

 

[mk3223]

IMO, as a material supplier, a spare brass rod sample should be saved from each production batch. And then, it could be used as a proof once there was any issue or complaint.
While questioning the structure change due to the forging process, how was the Engineer to prove the second batch was done correctly?

 

[arunmrao]

It is surprising that you do not have records or samples of the same for any future reference. Gracefully accept the customer's observation and have a course correction. Good for your business and the industry in general.

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

Mahatma Gandhi.

 

[EdStainless]

Without a ref sample this is your problem.
It could be at the fault of the forging, but just as likely it could be your fault.
In many brass alloys (unlike pure Cu) I would not expect a full recovery of the microstructure. While you will get recrystallization it will be effected by the initial structure.


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P.E. Metallurgy

 

[SahandSM]

Thank you for your replies.
you are all right, we should have kept our samples for longer.

we are trying to recall parts of the same batch from another customer. (we have provided another customer from the same batch and they had no complain about the product).

meanwhile, just to help me learn more about this, could you please comment on below points as general questions:
1- Do you believe the micro-structure demonstrated in the second picture can cause problems in forging process? (assuming the same micro-structure is valid for the rods before forging)
2- Do you believe a non-homogeneous micro-structure can be corrected during the forging process by choosing the right temperature leading to re-crystallization?

I have edited the original post to include these questions.

thank you all.

 

[MagBen]

Forging may or may not eliminate dendrites, but forging is unlikely to create dendrites. I think your casting probably the root cause.