Heat Treatable Engineering Steel

The use of heat-treatable steels covers the entire range of mechanical engineering, especially where dynamic stresses are present.

Some application examples are:

automotive parts such as crankshafts, axles, steering components,

axles in locomotive, shipyard and heavy engine construction

parts for machine tools and for mechanical engineering in general

shafts of turbines and generators in power plants

components and accessories for the oil and gas industry

fasteners, such as heavy-duty bolts

landing gear and control elements in aviation

tools for oil and gas exploration

Steel grades are selected to meet the property requirements for a given application.

The demand for higher strength and toughness requires an increase in alloy content to improve hardenability:

The carbon content increases systematically in the unalloyed qualities from {{0}}.22% to 0.55%.

Next, there are a series of grades with 1% Chromium (Cr) and 1% Cr/0,25% Mo with a carbon content increasing again from 0, 25% at 0,55%.

For components subjected to higher stresses, CrNiMo steels are used with an increase in nickel and chromium between 1% and 2%.

In NiCrMo steels, nickel is present up to 4% and Mo up to 0.7% to guarantee complete hardening of components such as generator shafts.

In CrMoV steels, carbon is partially replaced by alloys - up to 0.9% Mo - to maintain good weldability or extra high toughness.

The most important role of molybdenum in these grades is to increase hardenability and promote a uniformly hardened microstructure throughout the cross section.

This is illustrated by the following series: