Heat Treat 4130
Heat Treat 4130
(OP)
We have a customer that is requesting that we heat treat and quench .250 thick flat parts we make for them in water. The request is being made because they feel that the water quench give them better core toughness. We are concerned about this process. Does anyone have any experience in using water as quench media for 4140?





RE: Heat Treat 4130
RE: Heat Treat 4130
RE: Heat Treat 4130
RE: Heat Treat 4130
What is your concern using water other than inexperience? Can you test the process out on a section of 0.25" stock first? Can you use 4340 instead?
RE: Heat Treat 4130
RE: Heat Treat 4130
For your section thickness of 0.25in oil quench should be more than adequate and achieving a hardness of RC 45-47 should not be difficult.
In case customer insists on faster rate of quenching you can try polymer quenching where a polymer is added to water. The quenching is faster than oil without any fear of cracks. Hope thhis helps
RE: Heat Treat 4130
RE: Heat Treat 4130
RE: Heat Treat 4130
RE: Heat Treat 4130
I have considerable experience with 4330H material. We have quenched it in oil (upto 1.5 inch thick) and tempered it at 500F to get Rc 46 or higher. It has worked well for us and did not have any problems with cracking.
You should be able to oil quench 4330 and still get Rc 47 through out.
You may have to adjust the tempering temperatures depending on your as quenched hardness.
My person opinion : whenever possible stick with oil quench.
RE: Heat Treat 4130
You can quench this material in water and
even brine might be better. If they crack,
pass the cost on to the customer. How many
parts are you talking about? If you will not
do it, someone else will.
RE: Heat Treat 4130
I like this attitude of yours,if I do not a job,someone else will utilise this opportunity and this customer may never come back again,thinking you are unreasonable. But as long as the customer is willing to support let us also assist him by letting him know the pitfalls.
Right today I have had a customer who wanted me to polish as cast surface of a CF8M casting and provide a smmoth defect free surface without machining. My trying to convince failed. Please let me know what I can do. For if I ignore him someone else will take away the customer with a false assurance.
RE: Heat Treat 4130
And since your parts are only 1/4" thick, they will likely through harden given either quench. But the water quench will have a greater probability of producing more distortion or quench cracking. If your customer is made aware of this, they may decide that oil quenching is the better choice.
Maui
RE: Heat Treat 4130
Yield strength is closely related to the percent of as-quenched Martensite. Also toughness is in part a function of microstructure. And yes you can easily achieve the required hardness level with oil quench in this relatively thin section but if what HIMES stated "A water quench will result in a higher hardness than oil" is true does this not equate to higher percentage Martensite? So...when you temper this higher percentage Martensite to come up with the required hardness, you probably will have a tougher product like the customer wants.
Also if the geometry of the part is not complex or does not have geometric stress risers, then water quenching such a thin section should not hazard quench cracks. This phenomenon occurs from relatively thick sections because the core transforms later than the surface. Since Martensite takes up more volume than Ferite or Austenite, the later expansion at the core puts the surface in tension.
If the part has sharp changes in section or other potential quenching stress risers then prewarn your customer and then if cracks occur, so be it.
Jesus is THE life,
Leonard
RE: Heat Treat 4130