Problem- 4140 vs. 1045

[mmerriman]

Had a problem this week at the shop I work at. First off, we cut spindles for suspension parts all day long. That's most of the work we do. We only use 3 types of bar stock for the majority of orders - 1045 crs, 1145, and 4140. My problem is I had a blueprint that called for 4140 and I swear that they sent me 1045. Based on looks and machinability, I believe I was given the wrong material, but my supervisors pushed it on through. The bar stock was apparently marked from the supplier as 4140, but myself as well as two 20 year machinists I work with agreed that it was 1045. Any suggestions on how to correctly identify what grade of steel it is if it is marked incorrectly?? We are a somewhat high volume shop, with little QC support, and management that is hell bent on getting product out the door! Also, how much difference would this cause in the completed part/assembly??

[307startup]

other than doing a hardness test, I'm not sure there is anything you can do at your facility. There will be quite a difference in finish as well as ultimate strength in the finished part. 1045 might not hold a bearing race as intended. 4140 is much more springy than 1045 which typically fails quickly when pushed to its limits. I'd sure as hell never use a 1045 spindle for my automobile...

[Smrtman5]

If you could find really accurate density numbers you could machine equal sized samples and compare densities. However my brief search on matweb yielded .284 lb/in3 for both materials.

[.xXACEXx.]

im sorry if i mis-read you post...but you sy 1045 which is crs(cold rolled steel) 4140 is a tool steel which has carbon in it....so if you want to tell if it is not crs (if you have a heat treat oven) stick a small sample of the steel in the heat treat oven at around 1400 degrees for about 20-30 minutes if it is something like 4140 it should get harder if it is crs or hrs it should not get harder so to speak if you dont have a heat treat oven try a torch to heat the steel...or you might even get by with testing it out on a normal stove eye...turned to hight to get the steel very red hot (use a thin peice to test it this way so it will get hot faster) the steel if it is 4140 will get harder...hope this helps



oh yeah i forgot drop this "small" peice of steel in oil to "quench" it if it is 4140 ..this will harden it..make sure the peice goes all the way under the oil or it will smoke very bad.and leave it under the oil till it is cool. if you bring it out of the oil and it is still red hot..it will smoke ,and then possably set the smoke on fire with the peices own heat...so make sure its cool before you lift it from the oil....please use caution!! dont get burned...

[Pressfit]

It will be easy and quick to see the difference between 1045 crs and 4140 by doing a spark test with a belt sander or grinder. 4140 has a bit more carbon and will give shorter streams with a lot of branching, whereas 1045 will show longer streams with less branching. The difference will be obvious.

[Geof]

I cannot give you a diagnostic test to identify these to steels but I will comment that some of these posts are not exactly correct.

Here is some information about 4140:

The carbon content of this steel is 0.38 to 0.43 but has other alloying elements so it is an alloy steel.

4140 is a 1% chromium - molybdenum medium hardenability general purpose high tensile steel - generally supplied hardened and tempered in the tensile range of 860 - 1130 Mpa. Brinell hardness range 265 - 330 (Rc 28 - 36).
Characterised by high strength and good impact properties with good machinability, but low weldability.

Pre hardened and tempered 4140 can be further surface hardened by flame or induction hardening and by nitriding.

4140 is used extensively in most industry sectors for a wide range of applications utilising it's considerable savings on weight and machining time over solid bar.

Typical applications are: Bearings, Bushes, Cylinders (Various), Gears, Conveyor Rolls, Hydraulic Shafts, Hollow Shafts, Hollow Parts (Various), Nuts and Rings.

Heat Treatment

This alloy is hardened by heating to 1550 F and quenching in oil. It is best to normalize the alloy by heating at 1675 F for a long enough time to permit thorough heating, followed by air cooling, prior to the hardening treatment.

Here is some information on 1045:

This steel has a carbon content of 0.42 to 0.5 and it only has carbon and is a medium carbon steel.

1045 is a medium carbon steel is used when greater strength and hardness is desired than in the "as rolled" condition. Extreme size accuracy, straightness and concentricity combine to minimize wear in high speed applications. Turned, ground and polished bars can be machined unsymmetrically with minimum distortion.

Applications

Used in gears, shafts, axles, bolts, studs, and machine parts.

Heat Treatment

Suitable for flame and induction hardening.

In some posts it is mentioned that 1045 is Cold Rolled Steel. Normally when Cold Rolled Steel, CRS, is referred to what is meant is C1018 which is a low carbon steel with a carbon content of 0.15 t0 0.20

Here is some information on 1018:

Cold Rolled Type C1018 - A high quality, low carbon, smooth finished mild steel has good machining characteristics. It is easy to weld, braze and solder, making it a great material for models or prototypes.

This low carbon steel has good case hardening properties.
Although not classed as a screw machine steel at times it may be specified.
This is an excellent steel for bending and cold forming & is often used where cold forming stresses are not too severe.
C1018 has good brazing and welding properties.
It has a smooth - clean - cold drawn (rolled) surface.
Yield strengths are approx. 50000 PSI range & machine-ability is rated at 66% (c1212 = 100%) & 111 surface feet per minute.


Depending on the application it is possible the 1045 could work okay in place of 4140. It is likely that 1045 will machine better than 4140 but this does depend on whether it is annealed or hot rolled in an as-rolled condition.

[.xXACEXx.]

thanks for that techinical info geof, that just goes to show ya if you dont use it you lose it...i was actually thinking of 1018 crs when i posted that, it has been at least 4.5 years since i have done any heat treating of steel,i used to do all of it at the shop i worked at,but ill have to admit,we used alot more "tool steel" than crs,or hrs, or mild carbon types. stuff like a2,d2,m2,4140,4150,cpm9v,cpm10v and so on,.i even forgot the temp used to harden 4140 (1550) lol so as i said if you dont use it you will lose it .i do any way..

[pyro2525]

If you have access to a rockwell tester perhaps finding the hardness of your unknown material and comparing it to the hardness of known samples of 1045 and 4140 could give an indication?

[cam1]

How about a spark test, there are spark color charts that give an indication as to the type of material.

http://www.capeforge.com/Spark%20testing.html

regards

[mc-motorsports]

41XX means that molybendum is the major alloying element. 10XX means that carbon is the major alloying element. The last 2 or 3 digits of a AISI/SAE numbering system is the percentage of carbon by weight. 4140 being .40% carbon and 1045 being .45% carbon.

Use the grinding spark test as mentioned and compare against known samples. That's how the old toolmakers used to do it. Probably won't be a MAJOR difference seems how the carbon content is similar, look close and you should see a differance though.

[knot2swift]

1045 gummy and softer. I hate it for it's difficult to make a shiny finish using it. 4140 comes out with a mirror finish especially when facing while 1045 comes out grey with scratches.

Besides adding 1% Nickel to steel so it can be heat treated properly, It makes machining look nicer.

Same goes for Aluminum. "Just aluminum" is a pain but adding magnesium and silicon makes T6061 easier to machine plus you can heat treat it.

I'm here today looking for speeds/feeds using different cutting tools for Beryllium Copper myself. A little bit of Be in Cu makes it possible to harden and less gummy to work with. But it is tough stuff. A pain to drill and tap
but I'm looking mostly for milling data.

[Scanfab]

When milling BeCu, dont blow the dust/chips away into the air, the last thing you need is acute beryllium disease. If you think asbestos is bad, take a wiff of this.....Ive cut BeCu and wiped the machine down, no coolant to take dust in to tank.. Be is mostly machined under alcohol in a mill, covered in fluid in a "tank" on the mill table.