Steel
valves

Steel valves are the most common in medium-stressed engines. The steels used in this context have different characteristics according to their use:

• Steels with martensite structure: used for the manufacture of monolithic intake valves or for bimetallic valve stems. These steels withstand operating temperatures of up to 570°C and are toughenable.
• Steels with an austenitic structure: used for operating temperatures of up to 780°C; typical applications are medium-performance exhaust or intake valves in high-performance petrol or diesel engines. These steels harden by precipitation.

When the best of the characteristics of the two steels is required, SCARPA & COLOMBO manufacture bimetallic exhaust valves, in which the valve head is made in a material resistant to high-temperatures, while the remaining part (i.e. nearly all the stem) is in toughenable steel and has a greater wear resistance. The two materials are welded together by friction.

At the customer’s request we provide the necessary assistance for the choice of the materials.