Forging metals is a process that has been around for many decades.
It is important to understand the process as various industries are utilizing several types of alloys ranging from carbon, stainless, duplex, nickel, copper-nickel and titanium. These alloys are used in myriad applications for O&G, petrochemical, military, nuclear, pulp and paper and pharmaceuticals, to name a few. Most of these alloys are exceptional to corrosion resistance, attractive in appearance and have a high strength tolerance.
What is the forging process? Simplified, forging is a metal forming process in which forces are applied on the material to the extent that the stresses induced in the material are far greater than the yield stress; at the same time, they’re less than the ultimate stress so that the permanent distortion produced in the material will be used for changing the shape of the component.
A workpiece is heated to a high temperature and placed on a die or work region. A vast amount of compressive force is applied with either a similar die or hammers coming from a vertical direction, either intermittent or continuous, so that the shape deformation takes place.
The oldest form of forging is blacksmithing. This is the simplest form of forging in which the metal is heated at a high temperature, then manually beaten into shape on a metal anvil, using sledges or hammers to get the desired shape. Blacksmithing is an art and considered an ancient skill. As this trade continues to undergo a modern revival, forging, in general, is crucial in making the critical components to the O&G, petrochemical and various industries. Forging continues to be recognized as the premiere "thermomechanical" process.
Today, forging is done by means of hammers or presses, utilizing open-die or closeddie forging. Blacksmiths are still very much a part of the forging process, leading a crew of hammer operators and directing the forging process to ensure the desired shape is created efficiently while maintaining proper temperatures. Maintaining the temperature of the piece being worked on is crucial to workability and grain structure, which is essential to the strength of the metal in the finished piece. Working a piece too hot or too cold, even by a few degrees, can disrupt grain structure and ruin the structural integrity of the piece.
Open-die forging is the process in which the shaping of the heated metal parts comes between a top-die attached to a ram, and a bottom die attached to a hammer, anvil or bolster. It is important to note that the dies themselves do not enclose the metal, hence the name open-die. The metal is free to flow except where the die comes into contact. The piece still needs to be worked with tooling by the hammer operators to keep position and orientation to create the desired shape — disc, block, cylinder or custom shape. Opendie forging is common with the production of flanges. In closed-die, or impression-die, forging, the metal is placed within a die, similar to a mold, and attached to an anvil. The hammer die is also shaped, and when dropped onto the piece, the metal flows into the die, creating the desired shape.
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