Is EN353 cold forgeable as much as SCM420

[namelessudhay]

Hi,

We are doing a gear box for a two wheeler (for the first time). Most of our benchmarks are of Suzuki and Honda bikes. All their gears are made of SCM420. Surprising part is these gear teeth are formed by cold forging. No machining at all!

Now, I was comparing the chemical composition of SCM420 with EN353 and there were few components similar (C, Cr, Mo, Si) and few different. [ol i]

[li]Marginally high P and S in SCM420.[/li]
[li]Plus, there is a small addition of Cu in SCM420.[/li]
[li]Most importantly Ni is very less[/li]
[/ol]

I am not sure about the impact of these changes. However, I have read nickel provides more toughness and since EN353 contains more Nickel, can I cold forge gears with EN353 as well? Will I land up in any problem? Your help is very much appreciated. Thanks!

 

[TVP]

The addition of > 1.5% Ni increases the flow stress of the steel, making cold forging more difficult. The higher flow stress increases forces and hence stresses on the tools, which makes it more difficult to achieve adequate tool life. Most net-shape gears using EN353, SAE 4320, or similar high-Ni alloy steels are warm forged rather than cold forged. Warm forging at temperatures between 600 and 700 C typically produce similar accuracy/precision as cold forging, since scaling and oxidation is not significant in this temperature range. The flow stress is reduced by ~ 30 to 50% in this temperature range.