Forging is classified in hot, warm and cold, according to the temperature at which is performed. Although hot forging remains the oldest known manufacturing technique, the preference for the one or the other process, doesn&#;t depend on their quality but on the required characteristics of the final product and the production cost optimization, in accordance with the size&#;s batch of production. Forging refines the grain structure of the applied materials, mainly metals and alloys and thus improves the mechanical properties of the component making it stronger. Sophisticated hammers and presses are used to deform the material into a desired shape.
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Read more on Cold Forging vs. Hot Forging &#; Considerations, Benefits and Drawbacks
The hot forging manufacturing process is performed at the highest temperature which does not destroy the metallurgical features of the considered alloy (up to °C for steel, 300 to 460°C for Al-Alloys, 750 to °C for titanium alloys and 700 to 800 °C for Cu-Alloys).
Recrystallization occurs simultaneously with deformation, thus avoiding strain hardening. For this reason, and for best results, the forging temperature must be maintained throughout the entire process above a specific minimal, depending on the alloy. This condition avoids as well the risk of lack of forgeability, which leads to cracks as the ductility may be seriously reduced at lower temperature. The forging sequence is subsequently limited in time to respect these temperature limits.
If forging is not completed when the lower limit is reached, reheating is required when possible, or the part must be considered as forged, and finished by other means. The required interval of temperature for hot forging process is so important that all toolings are preheated to limit the loss of temperature of the component during the forging step. This had led to design a very accurate and specific process for closed die forging called &#;isothermal forging&#;.
During isothermal forging, the tools (actually dies) are kept heated at the required forging temperature. This concept however is applied very differently, depending on the type of the material, thus on the forging temperature itself. The material grade used for the dies must effectively keep the high mechanical properties required to deform the component material at the forging temperature.
Some examples of isothermal forging applied to different materials.
- It is quite mandatory for aluminum forging, as aluminum cools very quickly and forging temperature is rather low: all die grades sustain the required mechanical properties.
- It is possible for copper and titanium alloys, if a sophisticated (and expensive) grade is chosen for the dies.
- It is very difficult for steel alloys, where very few material (such as pure molybdenum) dies stand at °C the forging stress.
Therefore, isothermal forging is quite unusual for titanium alloys, and very confidential for steel and nickel based alloys (dedicated to the highest difficult turbine disks for jet engines for instance.)
Setforge provides high-quality isothermal forging process for aluminum alloys.
To prevent gas contamination which occurs during the hot forging process (O2, H2 or even N2 contamination) it is possible to protect the component by glass coating or controlled atmosphere (inert gas) within the heating furnace, induction heater and even press laboratory.
Hot forging begins with a forged metal ingot or a cast metal piece which gets &#;squeezed&#; in dedicated dies where its grain structure is broken down and homogenized into finer grains for increased yield strength and ductility. Because the metal is hot, it gets easily deformed and allows manufacturers to create more elaborate shapes than with cold forging. The fact that the metal is plastically deformed above its recrystallization temperature, allows it to retain its deformed shape as it cools. The shaping is followed by cooling, which is of critical importance as cooling hot forged parts too quickly can result in warping.
The hot forging process produces the most various shapes compared to other forging processes, and as the dies are not very expensive to produce, it is very well adapted to small batches and shapely components. Actually, other processes (warm and cold forging) are designed for high volume production such as automotive, and fasteners components, with simplier geometry, for which extremely complex dies can be designed, and amortized on a large number of parts produced with.
- Good ductility
- Possibility to manufacture customized parts
- Excellent surface quality
- High formability ratios
- Decreased yield strength and thus less energy required
- Increased diffusion and thus reduced chemical inhomogeneity
The functional areas of the component should be machined before assembly, as surface conditions, dimensional tolerances and residual surface contamination are not suitable to usual mechanical assembly design.
The material yield is higher than other (warm and cold forging) because of the scale produced during the heating, and because of the subsequent machining.
Cooling
As already mentioned above, cooling should be performed with an extreme care due to the risk of warpage.
Tolerances
Another important thing to consider when choosing hot forging is the less precise dimensional tolerance compared to cold forging.
Flash
Hot forgings can be divided into forgings with and without flash. These with flash possess complex 3D geometries compared to the flashless ones, generally limited to axisymmetric components or components with cyclic-symmetric geometries.
Dies
The dies used in hot forging are custom-made to match the customer&#;s part designs. The process is performed with drop, power drop or counterblow hammers, hydraulic or screw presses, and other similar machinery to compress the heated metal into the desired part shape.
Since the dies used in hot forging undergo sever thermal cycle and mechanical loading, cracking, plastic deformation, thermal fatigue cracking and wear should be taken into account. To prolong dies&#; life a good ductility and toughness and enhanced levels of both hot hardness and hot tensile strength are required.
Hot forging can be used to fabricate a broad spectrum of parts, and can be performed with most ferrous and non-ferrous metal alloys as:
· Structural steels
· Aluminum and magnesium wrought alloys
· Free-cutting steels
· Stainless steels
· Titanium alloys
· Molybdenum alloys
· Nickel/cobalt alloys
Most of the steel alloys are almost always hot forged, because as work hardening on hard materials advances, their deformation becomes more and more difficult. Furthermore, it is much more economically interesting to hot forge metals such as steel and then perform a heat treatment.
Hot forging remains the best available manufacturing process for complex shapes, heavy-weight components and high-duty alloys.
The most common hot forged product applications are mainly found in automotive, agricultural, aerospace and construction configurations, which require strength and durability.
The forging subsidiary of Farinia Group, Setforge masters the whole spectrum of forging techniques and provides a complete development of components, whether they are hot, warm, or cold forged. The Farinia Reseach & Development Team &#; Setforge Engineering possess solid metallurgical knowledge to adjust all required parameters in order to guarantee our customers the flawless design, simulation and execution of the entire process.
Being one of the top metal forging companies operating within China today, ChinaSavvy stocks a number of forging materials. Please note that we do work with a vast number of materials and that we are not restricted to working with just the metals listed on this page. Should you find that your desired grade is not on the list, please feel free to contact us directly.
The company is the world’s best Hot forging copper supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.
ChinaSavvy works with the following forging materials:
Typically forged by using hot forging processes, alloy steel is one of the most commonly used forging materials. Stronger, tougher and offering more resistance to wear when compared to carbon steel forgings, alloy steel are commonly alloyed with the following materials to enhance its physical properties:
Some of the more popular alloy steels used at ChinaSavvy includes:
Note: You can click on the table to view a larger image.
Note that we also work with Alloy Steel F11, F22 and F91.
Working with a large number of aluminum grades, ChinaSavvy is capable of producing high quality aluminum forgings to rival some of the best metal forging companies operating within the industry today.
Overall, aluminum alloys have a strong resistance to corrosion, while aluminum open die forging, when compared to casting, offers superior internal integrity, maximum impact strength as weel as an elimination of internal voids.
ChinaSavvy, working with a number of aluminum forging materials, offer the following aluminum die forgings:
Note: You can click on the table to view a larger image.
Also available in this category is AMS , AMS and AMS .
Please note that we work with a large number of materials and, if your desired grade is not listed here, you can contact us directly.
Learn more about the characteristics of the different grades of aluminum.
The ideal forging materials for high pressure and high temperature applications, ChinaSavvy works with the following forging materials in this category:
Note: You can click on the table to view a larger image.
ChinaSavvy also works with ASTM A105 Carbon Steel (which is forged at temperatures of between °F (926°C) and °F (°C), followed by normalizing or quenching and tempering) and ASTM A350 LF2 (which is forged between °F (900°C) and °F (°C) with soak times being kept to minimum in order to avoid heavy scaling).
Requiring special expertise to forge, the nickel based alloys used by ChinaSavvy includes, but are not limited to:
Note: You can click on the table to view a larger image.
Enhancing the existing qualities of stainless steel, forging is capable of improving stainless steel&#;s resistance to corrosion as well as creating a continuous grain flow.
ChinaSavvy works with the following forging materials in this category:
ChinaSavvy also works with the following forging materials in this category:
Titanium forged products range to include seamless rolled rings, shafts, disks, hubs, flanges, bars and block, to name but a few examples. Offering a combination of strength and a light weight, titanium is commonly the choice in applications where a high strength, high operating temperature, ligh weight or high resistance to corrosion is required.
Note: You can click on the table to view a larger image.
Commonly used to produce tools, ChinaSavvy works with the following tool steel grades:
These steels form air-hardening, cold work, medium alloy Group A steels.
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These steels are high carbon, high chromium steels, which includes:
Note: You can click on the table to view a larger image.
Other tool steel forging materials worked with at ChinaSavvy includes:
Please note that not all our forging materials are mentioned here. Being one of the top metal forging companies based in China today, we work with a large number of materials. Should you find that your desired forging materials do not appear on this page, please free to contact us directly.
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Further Suggested Reading
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