sae 1045 vs 4140

[pardal]

Hi All:

Whats are the pros and cons, of using any of such steel if both are used from the hot laminated round bar.?
Not previous or after heat treatment

The piece is the core and wing of a car cluthc.
This is made on a integral piece , so the internal splined hub form a unique piece with the wing.
I call wing the part where the springs are located on the called windows.

We had done a FEA studie and the stress is concentrated on the windows corner, having a value about 27 Kg/mm2.
I'm worried about a broaching process to make the splined internal hub.

Here in my country I can get BONIFICATED sae 4140 steel, this is HARDEN, AND TEMPERED TO ABOUT 25-30 hrc.

Actually we made this part in two pieces:
The hub from sae 12L38 , cold drawn , with out any Heat treatment.

And the wing from SAE 1010 cold laminated sheet , with internal thoot broached, then Carbonitriding to 0.25 to 0.35 mm to HRN15 88,then the tooth are drawn over the hub to locate it and make a solid piece.

The intention of making a solid one piece is because this one shall support a 65 Kg.m
torque.
If needed I can submit the drawings.

Thanks in advance.

Pardal










Pardal

 

[TVP]

SAE 4140 will have somewhat better machinability, due to the nominally lower carbon concentration. Due to the alloy content, it will work harden faster, which has implications for any forming processes. Other than that, there won't be a large difference in the hot-rolled bars.

Using an alloy steel such as 4140 will result in greater hardenability than a plain carbon steel such as 1045. Hardenability is defined as the depth to which a certain hardness level is maintained with a given quenching condition. Do not confuse hardenability with maximum hardness. SAE 1045 has a higher maximum carbon concentration, so it can achieve a higher overall surface hardness, but 4140 will maintain a given hardness level to a greater depth. Also, 4140 will have a significant improvement in fracture toughness compared to 1045 of the same or higher hardness.