2. Relaxation of casting stresses
Residual casting stresses (due to the complexity of the part's shape, the heterogeneity of thermal conditions during solidification and cooling in the mold, and the nature of the cast iron) are difficult to measure, but are sometimes indicated by deformation during machining, or even, exceptionally, by breakage.
In the mold, the thin parts solidify first and begin their solid state shrinkage, deforming the thicker, still incompletely solidified parts. These, in turn, contracting after solidification, develop tensile or compressive stresses throughout the part, which remain after complete cooling. It should be noted, moreover, that these stresses are distributed mainly in the surface regions, which is why deformations are particularly to be feared during the first machining passes.
the part...
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Relaxation of casting stresses
Annealing softening
Bibliography
References
Standardization
- Foundry – Designation system for cast iron. Symbolic and numerical designation. Replaces NF A 02-001. - NF EN 1560 - 09-97
- Foundry – Lamellar graphite cast iron. Replaces NF A 32-101. - NF EN 1561 - 10-97
- Foundry – Malleable cast iron. Replaces NF A 32-701 and NF A 32-702. - NF EN 1562 - 10-97
- Foundry – Spheroidal graphite cast iron. Replaces NF A 32-201. - NF EN 1563 - 10-97
- Foundry – Cast...
Organizations
Association technique de fonderie (ATF) http://www.atf.asso.fr/
Association technique de traitement thermique (ATTT) http://www.attt.org/
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