Cooling duct piston and method for producing the same

A cooling duct piston (1) for combustion engines, having a piston basic body (2) that is connected to a lining part (3), which lining part (3) faces an assigned combustion chamber,

• wherein the lining part (3) completely forms the piston surface (4) of the cooling duct piston (1) facing the combustion chamber,
• wherein an encircling depression (5) is provided in the surface of the piston basic body (2) facing the combustion chamber,
• wherein the lining part (3) provides a permanent connection at least to the surface of the piston basic body (2) facing the combustion chamber, thereby bridging the encircling depression (5), such that the circling depression (5), with the lining part (3) that bridges it, forms a cooling duct (6),
• wherein the material of the lining part (3) has a higher level of heat conductivity than the material of the piston basic body (2) and is a ferritic steel, aluminium, or an aluminium alloy and the material of the piston basic body (2) is an austentic steel, and
• wherein the material of the piston basic body (2) is an austentic steel stabilised with Ni, Mn, N, which has a thermal expansion coefficient in a range from 6 to 21×10−6 K−1.

A method for the production of a cooling duct piston (1) for combustion engines, having a piston basic body (2) that is connected to a lining part (3), which lining part (3) faces an assigned combustion chamber, wherein the lining part (3) completely forms the piston surface (4) of the cooling duct piston (1) facing the combustion chamber, wherein an encircling depression (5) is provided in the surface of the piston basic body (2) facing the combustion chamber, wherein the lining part (3) provides a permanent connection at least to the surface of the piston basic body (2) facing the combustion chamber, thereby bridging the encircling depression (5), such that the circling depression (5), with the lining part (3) that bridges it, forms a cooling duct (6), and

• wherein the material of the lining part (3) has a higher level of heat conductivity than the material of the piston basic body (2) and is a ferritic steel, aluminium, or an aluminium alloy and the material of the piston basic body (2) is an austentic steel, the method comprising the following steps:
• inserting the lining part (3) into a cavity of a mould for a piston basic body (2), wherein the shape of the cavity has a negative form for the encircling depression (5) and the negative form is kept free from the lining part (3),
• filling the mould with the material for the piston basic body (2), thereby at least partially moulding the lining part (3),
• cooling and demoulding the piston basic body (2) with the moulded lining part (3), and
• reshaping at least one non-moulded section of the lining part (3), thereby bridging the encircling depression (5) and forming the cooling duct (6).