Heat treatment of precision investment castings is a metal processing technology to obtain expected properties by heating, warming and cooling. Heat treatment is one of the main technologies during investment casting process. After heat treatment, it will not change the shape and whole compositions of investment castings, but will endow or improve the working performance of products by change the inner microscopic structure, or change surface compositions of investment castings. Investment casting heat treatment expands the mechanical properties of metal alloys by providing higher thresholds of corrosion resistance, abrasion resistance, and hardness.
Heat Treatment Capabilities in FHND Precision Casting
Precision Investment Casting of FHND offers wide selection ways of heat treatment service. With long term professional heat treatment partner, we can privide below heat treatment methods with low cost in below:
1. Normalizing: Heating investment casting blanks to or above critical point temperature AC3 or ACM and maintain a certain time, cooling in the air to get the pearlitic tissue. Aim of normalizing is to improve the mechanical properties of low carbon steel, improve the cutting processability, refine the grain size, remove the tissue defects, and ready for further heat treatments. Normalizing is more suitable for engineered carbon steel investment castings and thick,big and complex alloy steel investment castings.
2. Annealing: A kind of heat treatment methods that heating investment castings to proper temperature for a while, and cooling down slowly. Annealing is mainly used to lower the hardness,improve plasticity for further machining, and reduce residual stress of investment castings.
3. Tempering: Improves ductility, crack resistance, malleability, and toughness of products. Through controlled reheating, we are able to quickly reduce the brittleness of investment castings.
4. Quenching: Quenching is a process of cooling investment castings at a rapid rate. This is most often done to produce a martensite transformation. In ferrous alloys, this will often produce a harder metal, while non-ferrous alloys will usually become softer than normal. To harden by quenching, investment castings (usually steel or cast iron) must be heated above the upper critical temperature and then quickly cooled.
Attention: However, most non-ferrous metal castings, like alloys of copper, aluminum, or nickel, and some high alloy steel castings such as austenitic stainless steel investment castings (304, 316), produce an opposite effect when these are quenched: they soften. Austenitic stainless steels investment castings must be quenched to become fully corrosion resistant, as they work-harden significantly.
5. Eliminating hydrogan treatment: The purpose is to remove hydrogen, improve the plasticity of steel castings.
6. Carburizing Treatment: Carburizing is the process of directing carbon element into the surface of investment castings. It will greatly improve the surface hardness and wear resistance by change the carbon composition of products, but still keep low hardness inside.
7. Tempering and Hardening: Compound heat treatment process by quenching and high tempering tempering of investment castings. This kind of heat treatment way is normally used to improve the both surface and innner hardness of precision investment castings. Especially for those replacement wear parts.
8. Case Hardening: Also referred to as surface hardening, this method infuses hardening elements into the surface of investment castings, thus to provide an extra protection layer.
Above are the main heat treatment ways listed for investment castings. Heat treatment is carried out mainly according to the application of investment castings. If you are not familar with heat treatment, no problem, our engineer will suggest the right way if your products do require this service. Contact us once you are in need of our heat treatment service.