20CrMnTi Vs 20CrMn 1

[bagnamento]

Hi,
I was asked this question by a friend who works with gears.

They use to make gears with 20CrMn steel (carburized+quenched) and their usual suppliers are offering 20CrMnTi steel as an alternative.
What is the role of Ti in this alloy? How do material properties change?

Would there be any major variation in heat treatment parameters due to the presence of Ti?

Thanks,

 

[adyonel]

bagnamento,

Titanium decrease hardenability of steels with medium content of chromium, but not too much.
The heat treatment is the same for both of steels. It is possible to obtain after heat treatment some carbide network.

 

[TVP]

Ti, V, and Nb all combine with N and/or C to form small particles of titanium nitride or titanium carbonitride. These small particles will affect the nucleation and size of austenitic or ferritic grains. The following is a short excerpt from a recent journal article on this subject:

"New Microalloyed Steel Applications for the Automotive Sector by David K. Matlock, George Krauss, and John G. Speer, Materials Science Forum Vols. 500-501 (2005) pp. 87-96

The key to the use of microalloying in automotive components is the relative temperature dependent solubility of the microalloying elements as determined by the reactions of the microalloying elements with C and N. The temperature ranges in which carbides, nitrides, and carbonitrides form and dissolve determine whether or not a given microalloying design is appropriate for a given application. Precipitates of V, Nb, and Ti, in that order, are increasingly stable with increasing temperature. Therefore, TiN, which is stable at temperatures in excess of 1200 C, makes possible austenite grain size control at high forging temperatures and during high-temperature carburizing.