4140T...is it necessary to make it a heat treating? 2

[Saver2008]

Hi all!!!

I´m trying to make a replacement of a power drill (see item on attached file). The last item broke it by torsion action, I´m thinking to make this new item on 4140T but I do not know if it is necessary to make a heat treating to this item. I pretend to use 4140T in order that this item will not fail and also I´m using 4140T in order to not to make it a heat treating. If the item were gonna be made of 1018 or 1045, it´d need a heat treating but how it is 4140T, It is not necessary (I think)...
what do you think?

 

[CoryPad]

4140 that is not hardened and tempered will not be great for this application. It should do well (compared to 1018 and 1045) if it is hardened and tempered - maybe target 40 HRC for hardness.

 

[Saver2008]

Thanks CoryPad. 4140 without "T", it is with no heat treating. It is supposed that when you buy a bar or other item in 4140T, this item already has a heat treating....or am I wrong?

 

[metman]

Saver2008

Maybe the T designation is something relatively new but I have never seen 4140 designated that way. You can purchase it heat treated (quenched and tempered) for example from Ryerson at 1550F, Oil quench, 1000F temper which gives approximately HRC 40.

It comes in three tempers or three conditions from Ryerson:
Hot Rollled
Cold Drawn
Quenched and Tempered

So you need to spell it out just like that:

Geometry/Size, 4140 Quenched and Tempered

 

[gearcutter]

4140 T is in a hardened and tempered state. Depending on the size; expect around 1080 - 1230 MPa or 34 - 39HRC at the surface.

Ron Volmershausen
Brunkerville Engineering
Newcastle Australia

http://www.aussieweb.com.au/email.aspx?id=1194181

 

[Saver2008]

4140 T. The "T" means TREATED. It means, it´s been already heat treated. Now, this BAR, already treated, I make the "slots" and that is....but is it required other heat treating?

 

[metman]

Hardened and tempered = quench and tempered = heat treated

For each of the above descriptions, it is passed tense or already treated.

 

[gearcutter]

"T" does not stand for treated.
It represents the level of hardness to depth which has been achieved. It is generally referred to as "condition T".
Another common designation is "condition U" which is slightly harder.

Ron Volmershausen
Brunkerville Engineering
Newcastle Australia

http://www.aussieweb.com.au/email.aspx?id=1194181

 

[DAVIDSTECKER]

Personally, I'd look in to 8620.

 

[arunmrao]

Can someone explain the rationale behind offering material in T condition. If the bar stock,undergoes machining,followed by slotting and or drilling and tapping,will it not be difficult as compared to completing the operations in normalised condition and then heat treating to the desired hardness.

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year

 

[gearcutter]

No heat treatment after machining generally results in no distortion as a result of the quenching/rapid cooling process.
No post machining heat treatment also means less cost.
Most of the blanks we gear or spline cut are either 4140 or 4340 in condition U or T. All our tooling is HSS and most of it is uncoated.
Condition U or T is still considered to be machinable even with HSS cutters.
Today’s modern machines and tooling actually prefer the harder materials as it chips more cleanly helping improve finish and chip control & removal.
Machines are now available which can finish machine up to 60HRC using ceramic or diamond tipped inserts. This can mean a large cost saving in the production of the part as no further heat treatment would be required.


Ron Volmershausen
Brunkerville Engineering
Newcastle Australia

http://www.aussieweb.com.au/email.aspx?id=1194181

 

[arunmrao]

Thanks gearcutter for providing the clarification. One last question, how do you deal with residual stresses built during machining,will there not be a shifting of dimensions over time.

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year

 

[gearcutter]

Yes, this can be a problem particularly with long slender items.

We have a double ended splined shaft, which we regularly manufacture, which is long and slender.
The material is 4140 T.
The part requires a rough turning process and is then given time to undergo a mild form of stress relieving before finish turning.
All that is required for the stress relieving is for the shafts to be stored under cover outside in the weather for a week or so; not strictly stress relieving..........I know.
The amount of deflection the shafts undergo during this period only seems to happen once and is corrected during the finish turning operation.
It would be impossible to through harden these parts after machining as they would end up looking like bananas

Ron Volmershausen
Brunkerville Engineering
Newcastle Australia

http://www.aussieweb.com.au/email.aspx?id=1194181

 

[arunmrao]

gearcutter a star to you.

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year

 

[metman]

"T" does not stand for treated.
It represents the level of hardness to depth which has been achieved. It is generally referred to as "condition T".
Another common designation is "condition U" which is slightly harder.

Is this an industry designation e.g. AISI, SAE, AMS or a particular vendor? What hardness and what depth for condition T?

If the T does not stand for Treated, how is the condition "achieved?" Maybe by cold work?

 

[gearcutter]

Just google it. Heaps of info available on the web if you look for it.

Ron Volmershausen
Brunkerville Engineering
Newcastle Australia

http://www.aussieweb.com.au/email.aspx?id=1194181

 

[metman]

Google search via "AISI 4140T" yields:

alloy structural steel, 4140/4140T by alibaba.com in China. But no properties given. 10 ton minimum!

Google search via "4140T alloy steel properties" yields.

same thing plus:

Influence of Fatigue Damage in Dynamic Tensile Properties of AISI ... "Dynamic tensile behavior of materials with previous fatigue damage ..."

This article talks about effect of intentional fatigue damage on tensile properties of 4140T. But nothing on hardness or depth of hardness.

I feel like the old Indian in "Every Which Way But Loose" where Clint Eastwood comes up slowly behind the Indian. The Indian said, "I'm getting too old...let a white man sneak up on me!"

I am getting too old...can't do a decent Google search.

 

[gearcutter]

Google search for "4140 steel properties". Third one down yields this brochure:

http://www.interlloy.com.au/data_sh...igh_pdf/Interlloy_4140_High_Tensile_Steel.pdf

Look for the heading "mechanical properties designations".

That's a great scene from the Clint Eastwood movie "The Outlaw Jose Wales".

http://www.youtube.com/watch?v=Hvf8r3cX3vo

Ron Volmershausen
Brunkerville Engineering
Newcastle Australia

http://www.aussieweb.com.au/email.aspx?id=1194181

 

[metman]

gearcutter,

This must be what you were directing me to:

Mechanical Property Requirements for Steels in the Heat-Treated Condition for Turned,
Peeled or Ground Finish to AS1444-1996 4140 and BS970 Part 3-1991 709M40

R 63 700 850 525 12 201 255
S 63 770 930 585 11 223 277
T 63 850 1000 680 9 248 302
U 63 930 1080 755 9 269 331
V 63 1000 1150 850 9 293 352

Still no see anything in reference to depth of hardening.

Thanks for the correction of the Movie title.

 

[Saver2008]

Thanks to all.

I have applied it and it got deformed. Teeth got torsionated. I assume that even when 4140T has already a treatment, machining effects and also all stress according to its work or purpuse, made it to get deformed. As per all your comments, I will try to use 4140 R or without any treaating, then I will give it a heat treating in order to achieve some Brinell hardness.
What do you think?