Production verification of horizontal casting for medium speed diesel engine block

The casting process test of diesel engine block was carried out by using the process determined by analysis. The production verification shows that the process scheme is feasible. There is no sand hole and air hole in the casting during production. Figure 1 shows the appearance of the body casting after machining. The appearance of the casting is complete and the surface is smooth. The dimensional accuracy of the key parts of the casting meets the production requirements. The sand core of the water channel is not broken and the wall thickness is not uneven due to the floating of the sand core.

After the impeller is unpacked and cleaned, the gate part is heat treated with the impeller in the same furnace, and then the metallographic samples of the gate are taken for testing. The picture shows the metallographic sample of impeller gate. It can be seen that the grains are refined, the carbides are embedded in the martensite matrix in the form of block and strip, and the edge of eutectic carbides is globular; the dispersion degree of secondary carbide in the matrix increases, and the precipitation phase of secondary carbide in the matrix increases.

The same process was used for small batch production of large impellers. A total of 7 large impellers were manufactured with good quality and no defects. The field operation test results show that JX material impeller is safe and reliable without cracking, and its service life is more than 14 months, which is more than twice the service life of ordinary high chromium cast iron.

1) The trial production of high chromium cast iron JX material is successful. The target performance indexes are: hardness 54 ~ 60 HRC, tensile strength RM ≥ 650 MPa, impact toughness AK ≥ 8 ~ 10 J / cm2; the measured performance indexes are hardness 54 ~ 56 HRC, tensile strength 740 ~ 800 MPa, impact toughness 8 ~ 10 J / cm2.

2) The results show that the strengthening effect of JX-1 modifier on high chromium cast iron JX material is excellent. The addition of 0.030% is more effective than that of 0.015% on the microstructure refinement and comprehensive mechanical properties of JX material.

3) Using JX material, the trial production of large impeller has been successfully realized through reasonable design of casting process, heat treatment temperature rise and cooling rate. The hardness test of large impeller and metallographic analysis of the gate of heat treatment in the same furnace prove that the application of JX material in large impeller is feasible and the effect is good.

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