Hardening EN8 & EN9 parts
A discussion started in 2009 but continuing through 2018March 2, 2009
Q. With en9 material can I get hardness of 44-48 hrc on all over the part. If yes, then can you suggest the h/t cycle. Because we are manufacturing one product which has an elliptical broach in middle in which we can't get hardness 44-48 hrc and also we found that our broach dimensions has also get variation after final heat treatment. So can you help for getting hardness 44-48 hrc?Vishal Sachde
- Bhavnagar, India
March 6, 2009
A. En9 is a plain unalloyed medium-carbon steel. It therefore requires very severe cooling in the heat treatment cycle in order to get the sort of hardness that you want, and the thickness of the section in turn greatly affects the cooling rate that can be achieved.
Information that you must supply to get further with your query:
1. What section thickness is your component?
2. To what depth below the surface do you want 44-48 HRc?
3. Related to Q2, do you want through-hardening?
4. Do you have a soak-and-water-quench facility?
5. Do you have a flame-hardening facility?
Depending on answers to the above, there might be a heat treatment cycle that will give you what you want on En9, or it might be that you will need to change grade to one that has appropriate alloy content to allow hardening by less severe quenching.
Ballarat, Victoria, Australia
We sadly relate the news that Bill passed away on Jan. 29, 2010.
March 9, 2009
A. Good afternoon:
With limited information provided, it's going to be hard to tell whether 44-48 HRC is possible. Part dimensions, thickness, quenchant, quench agitation, variation of chemistry from heat to heat...these are some of the variables that should be considered.
And since this is a 0.50-0.60 carbon material, if the quench rate is too severe, warpage or quench cracking are possibilities. This might explain the variation in the broach dimension. If these are thin parts, you might be able to austemper or marquench them to reduce warpage.
If you buy steel with a guaranteed hardenability band, you could better predict the heat treat response.
If the part is too thick to achieve adequate as quenched hardness, a change in material may be needed.
Sorry there's no quick answer. Good luck.
- St Louis, Missouri
March 12, 2009
A. Obviously it is possible to get hardness 44-49 hrc in en 9, but please specify section thickness?
Please specify whether dwg. requires thru hardening and / or surface hardening?
We are doing similar components; also specify whether dwg. specifies core hardness too?
I would advise more quenching to avoid problem of distortion
Just for sharing, had manufactured EN king pins which were toughened to 25 Rc at core then surface was induction hardened in polymer quenching to give 55 hrc hardness at surface to depth of .5 mm thus achieving strength as well as wear improved surface life.
- Chandigarh, India
October 6, 2011
Q. In EN9, C45 material Flats and Bars, we could not get the Hardness of our requirement of above 50 HRC as quenched condition in oil quenching.DEVA RAJAN
Heat Treatment Manager - COIMBATORE, Tamilnadu, India
March 10, 2012
Q. Our Components fall within following dimensions-
LENGTH- 50 mm to 150 mm
WIDTH- 07 mm to 20 mm
THICKNESS- 0.8 mm to 1.5 mm
MATERIAL USED- EN9
Can anyone please suggest an appropriate Heat Treatment process to achieve an through 40-48 HRC?
- CHENNAI, Tamil Nadu, INDIA
A. Yes, apart from my experience 0.75 ~ 1.50 mm thickness EN 9 material can get easily 40 ~ 48 HRC by doing the components at mesh belt hardening furnace which will have not much % of Carbon enrichment and decarb due to continuous hardening. As quench condition the hardness will be 55 ~ 60 HRC then have to temper it 320 ~ 340 °C for one hour. Normally this will not have major distortion issue. Otherwise the same Mesh belt furnace with Austempering (quench at 350 °C) will give 42 ~ 48 HRC and there is no need of further tempering.DEVARAJ [last name deleted for privacy by Editor]
- KARUR, TN, India
January 4, 2013 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread
Q. What is the Maximum Hardenability of EN9 material in Oil quench. Chemical composition are C - 0.55, Si - 0.15, Mn- 0.75, P-0.003, S- 0.005.DEVARAJAN LAKSHMANAN
- COIMBATORE, India
May 7, 2014
Q. Hi sir
I want the details of the EN8 steel hardness and it is used to take a wear test on the austempered ductile iron, and I have hardness of the material of 33 HRC.
student - madurai,tamil nadu,india
July 3, 2014
Q. I am a Commercial heat treater
We received one tube mill roll for heat treatment
The size is 520 mm Dia. X 320 mm
What maximum hardness can I get by Oil Quenching?
metal treatment services - Ahmedabad, Gujarat, INDIA
Hi, Devarajan, Gopi and Bharat. Sorry, I have no knowledge of heat treatment. All I can do is coach you that I've learned from 20 years of postings here that any questions which resemble simply starting over instead of building onto the discussion are invariably ignored; if you can cast your question in terms of the answers already offered, they'll usually elicit enthusiastic response. Is there a way that you can study what has been said and try that approach? Thanks!
Ted Mooney, P.E.
Pine Beach, New Jersey
April 10, 2016
Q. Hi sir,
I want to know the heat treatment procedure of EN-9 Material to get 36- 47 HRC through hardening. actually we are doing hardening with the temp of 820/840 °Cs but we are getting as quench hardness very low (18-20 RC). Kindly give the solution for this.
- Pune, India
April 17, 2017
Q. Material EN9, Hardness required 300 to 350 BHN, size Dia 680 mm thickness 200 mm with bore of 135 mm. Weight is approximately 300 kgs. Please suggest the feasibility of achieving the required hardness and the process parameters.Vijayendra T R
- Bangalore, India
How to achieve hardness up to 45-50 HRC on C45?May 8, 2017
Q. With C45 material can I get hardness 44-50 hrc by case hardening?
Length is 91 mm. Pin diameter is 25 mm. And two steps are at both end with diameter 12g6. And surface treatment is hard chrome plating. Required case depth is 0.8-1.2 mm.
buyer - pune, Maharashtra, India
Hi Rajkumar. Thanks for the good detail on your component. We posted your question and we hope you will receive an answer!
Readers: four people offered generous & insightful responses early on; although the thread receives continuing questions, and tens of thousands of viewers, no answers have been offered in 4 years now! Our experience has been that when readers offer their help, they are hoping that posters will engage them in dialog, appreciating the opportunity to learn; but if the posters instead try to steer them into a "flash card quiz" of slightly changed materials, hardness, and dimensions, they invariably decline to play :-(
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"
May 17, 2017
A. Hello Rajkumar!
You need to case harden C45 up to 44-50 HRC, I should say you can achieve that hardness without difficulties.
That hardness is the case hardness or the core hardness? If it is the case hardness, is there any specification for core hardness?
If you already solved this, please let us know! Regards,
TEL - N FERRARIS - Canuelas, Buenos Aires, Argentina
June 17, 2017
I would like to know about the volume hardening of En9 to achieve the core hardness of 330-355 BHN. The forged shaft diameter is 45 mm and length is 400 mm with one end disc diameter of 250 mm and length 30 mm. If so, please suggest the H/t cycle.
Lakshmi Machine Works Limited - Coimbatore, Tamilnadu, India
October 27, 2017
Q. We have EN8 material of cylindrical(solid), length= 300 mm, diameter= 60 mm. Our hardening company person promises to harden it at 55C, but there is too much variation in the diameter after hardening. Is it because of continuous hardening more than its capacity? What is the optimum hardness we can expect?SAURABH KUMAR
- Noida, India
November 8, 2017
A. Hi Saurabh!
EN8, in my experience, is not a good material for hardening. In 60 mm thick you need, at least, some boron and chromium in your composition to improve hardening depth.
Hardenability is below 50 HRC for more than 6 mm from the surface, maybe you can get this number higher with brine quenching, but not 30 mm (distance from surface to the center).
Best of luck!
TEL - N FERRARIS - Canuelas, Buenos Aires, Argentina
March 24, 2018
Q. Hello there, we make pins from 3 mm to 16 mm dia. and 8 mm to 150 mm length, only in EN8D material. We do hardening process with docking and cooling in salted water. Still we get variation in hardening. We want 48-52 hardness. But very few times do we achieve the target. So can anyone help me with the exact formula to get proper hardness?
Minimum size:- 3 dia x 8 length to 60 mm
Maximum size:- 16 dia x 40 length to 100 mm
PLEASE REPLY ME. THANK YOU.
Vijay Engineering works, Ahmedabad. - Ahmedabad, Gujarat, India
May 11, 2018
I want to know how to achieve hardening in material EN8D.
We did arc quenching and oil quenching. But it didn't help us.
If anyone knows, kindly help.
- Rajkot. India
July 19, 2018
Q. Hi sir,
We are facing same problem re. hardness in EN8 round bar . The surface of the material is reaching 34-35 HRC but at the core of the material is getting 25-26 only. Please suggest how to rectify the problem.
Quality incharge - Coimbatore, Tamilnadu, India
Insufficient hardness achieved in heat treating C45 MaterialJuly 24, 2018
Q. My situation:We have taken C45 grade 4.00 mm thick 70 mm wide material for hardening. Carbon % 0.425 and Mn% 0.66. In last lot used with same heat material hardness achieved 46 to 48 HRC, this month lot achieving hardness 37 to 38 HRC only. What are the probable reasons for non achievement of hardness?Ashish kekre
Buyer - Dombivli, Thane, Maharashtra, INDIA
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