| 摘要 |
PURPOSE:To simply and easily produce an inexpensive piston having excellent resistance to thermal impact and thermal fatigue by disposing Cr or Mo on the prescribed section of the cast iron piston and irradiating high-density energy thereon then subjecting said section to an adequate reheating treatment. CONSTITUTION:The Cr and/or Mo or the alloy thereof or the alloy with Fe is disposed onto the surface of a hot spot part 4, where the resistance to thermal impact and thermal fatigue is requested, of a piston head part 2 of a rough shape material 1 for the cast iron piston. The high-density energy such as laser is then irradiated thereon from above to form the alloy layer by quick melting- quick resolidifying. The alloy layer is thereafter subjected to the reheating treatment to heat said layer for 1-10min at 800-1,050 deg.C. The alloyed cast iron layer which contains 0.3-2.0wt% Cr and/or Mo and is dispersed and crystallized with block graphite in the pearlite base or the base essentially consisting of the pearlite base is thereby forming to the above-mentioned section down to >=0.2mm depth from the surface. The cast iron piston having the improved resistance to thermal impact and thermal fatigue in the required section and a long life for an internal combustion engine is thus obtd. |
