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Dear Sir/Madam experts,

I've some problem quenching problem for 4140 etc. steel at car bottom type heat treatment furnance. Austenizing temperature 880C. Quenching media is polymer. Consantration is nearly %12-13. The Materials is bloom. The diameter is 400mm. I measure nonuniform hardness profile at same charge with the other materials. But the other materils is ok.

And also the other problem is almost same. But the furnence is fit type furnance, quenching media is salt bath that is 150C. The material has rust of bottom after quenching and low hardness according to top of material.

The last, what is your opinion dimension difference quenching process at same charge?

Thank you for your attention.

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Burak Turk
Material Science Engineer
Termo Induction Heat Treatment and Machine Industry
Tuzla
+905314750609
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Hello Burak,

For better results we should think about the two processes that lead to a good quenched part: austenitization and quenching

• Austenitization
  • Proper temperature
  • Proper soaking time
    • To allow the inner portions of the material to reach austenitization temperature
  • Uniform temperature in the part
    • All the furnaces have deviations in the temperature across the working volume, but this "spread" should be measured and controlled
•  Quench
  • Media temperature
  • Agitiation or velocity
  • Composition of quenching media

There are multiple failure modes in the process and they yield different results in the part. According to what you mention, I recommend you to look at the agitation of your quenching system, there might be clogged nozzles or blind spots in the agitation. Also validate the quench curves of your quenching media, polymer may degradate over time or with improper care due to bactariae. In conclusion, ensure that the heating as well as the quench are as uniform as possible.

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Jose Flores Herrera
McMaster University
Hamilton ON
(128) 994-1124
floreshj@mcmaster.ca
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Original Message:
Sent: 02-18-2024 15:50
From: Burak Turk
Subject: Nonuniform Hardness Profile at Quenching

Dear Sir/Madam experts,

I've some problem quenching problem for 4140 etc. steel at car bottom type heat treatment furnance. Austenizing temperature 880C. Quenching media is polymer. Consantration is nearly %12-13. The Materials is bloom. The diameter is 400mm. I measure nonuniform hardness profile at same charge with the other materials. But the other materils is ok.

And also the other problem is almost same. But the furnence is fit type furnance, quenching media is salt bath that is 150C. The material has rust of bottom after quenching and low hardness according to top of material.

The last, what is your opinion dimension difference quenching process at same charge?

Thank you for your attention.

------------------------------
Burak Turk
Material Science Engineer
Termo Induction Heat Treatment and Machine Industry
Tuzla
+905314750609
------------------------------