Users of metals in Jasa Heat Treatment di Medan the manufacturing industry have learned how to improve vast varieties of metals. This is mostly done to tailor their properties to fit into the task at hand such as reaction to precision machining.
There are vast methods to improve metals, one of which includes heat treatment of metals. This process can alter a number of different properties including strength, formability, elasticity, hardness, ductility, and machinability.
As the topic of this article implies, this article focuses on everything you need to know about the heat treatment of metals.
What is Heat Treatment of Metals
Heat treatment is a general process of the usage of heating and cooling operations at various staged levels to alter the physical properties of metals (microstructure) such as steel, aluminum, and many more. The major purpose of such treatment is to improve the physical and structural properties for some specific use or future work of the metal.
There are vast varieties of heat treatment processes out of which include case hardening, annealing, tempering, decarburizing, normalizing, case hardening, aging, quenching, and more. While each of these heat treatment brings about different results in metal, they all involve three basic steps. These steps include heating, soaking, and cooling.
The Advantages of Heat Treatment of Metals
In the world of manufacturing, heat treatment of metals is generally used and it is a precisely controlled process of heating and cooling. Heat treatment does not only make the metal harder, but it also makes it softer too. The softening allows metals for working operations such as cold forging, machining, deep drawing, and many more. The heat treatment of metal is beneficial and they include the following:Improvement in machinability or workability:
Heat treatment helps to improves a metal’s manufacturability. This is done by the removal of internal stress from previous fabrication processes such as hot work, cold work, machining, welding, and stamping. For example, if a metal is highly hard to bend or machine, it can be subjected to annealing or tertekan relieving. This will help to reduce the hardness of such material. If a material deforms when machined, to keep it from deformation, the material can be annealed or tertekan relieved. Heat treatment using induction or flame can also be used the soften a specific area of the metal, leaving the remaining part of the metal untouched.Improvement in Durability and Wear Resistance
There are several heat treatment processes out there. Some of these processes can be used to improve wear resistance by hardening the metals involved. Metals such as titanium, steel, Inconel, and some Jasa Heat Treatment di Medan alloys of copper can be hardened either on the surface (case hardening) or through (through hardening). This is done to make the material stronger, more durable, tougher, and more resistant to wear and tear. This method is the best method commonly used to increase the durability of inexpensive steel including 1018 or A-36.
Localized hardening can be done either by induction or by flame. This can also help to harden a specific part leaving the rest part of the material untouched or unchanged. Lastly, nitriding is used to harden the part surface at low temperatures to reduce distortion.Improvement in Toughness and Strength
Toughness and strength are a trade-off, as increasing strength as measured by hardness can help to reduce toughness and introduce brittleness. Consequently, heat treatment can affect the tensile strength, yield strength, and fracture toughness. Through hardening or case hardening will help to increase the material’s strength. However, the material will be required to be drawn back or tempered to reduce brittleness. The extent of tempering is determined by the ultimate strength required in the part. Besides, if the received material is too brittle, it can be heat treated either re-tempered or annealed to make it more usable (ductile).Improvement in Magnetic Properties
Many metals including 316 or 1008 tend to gain magnetism which is measure as magnetic permeability. This is mostly obtained when the materials in question are work-hardened using methods including machining, stamping, forming, and bending. Aside from gaining magnetism, there is a specific type of annealing process that helps to reduce magnetic permeability. This is important to be carried out if the part has an application in an electronic environment.
What Metals Can Be Heat Treated?
In the world of heat treatment, ferrous metals account for the majority of heat-treated materials. About 80% of heat-treated ferrous metals are the different grades of steel. Other examples of ferrous metals that are heat treatable include stainless steel and cast iron. However, other metals including, magnesium. Aluminum, nickel, titanium, brass, copper alloys, and many more are heat treatable.
Heat treatment of aluminum helps to strengthen and harden a specific subset of alloys of aluminum. This includes wrought and cast alloys that are precipitation hardenable. These precipitation-hardenable alloys of aluminum include 2XXX, 6XXX, 7XXX, and 8XXX grades. Annealing may also be required for parts that have undergone strain hardening in their forming process.
The typical heat treatment of aluminum includes annealing, natural & artificial aging, homogenizing, and solution heat treatment. While the heat treatment of aluminum differs from other metals such as steel, its furnace temperature can range between 240 and 1000oF depending on the exact process being used.
As mentioned earlier, the most heat-treated ferrous metal is steel. The adjustment of the carbon content of steel is the simplest heat treatment of steel. This helps to change the mechanical properties of steel. Additional changes are done by heat treating – for example by accelerating the rate of the cooling through the austenite-to-ferrite transformation point. Also, increasing the rate of cooling of pearlitic steel (0.77% carbon) to about 200oC per minute generates a DPH of about 300, and cooling at 400oC per minute rases the DPH to about 400. The increasing hardness is attributed to the formation of a finer pearlite and ferrite microstructure that can be obtained during slow cooling under ambient air.
In general, the commonly used heat treatment process for the steel include annealing, quenching, tempering, boronizing, carburizing, case hardening, nitriding, decarburizing, cyanide hardening, and many more. However, not every steel grade is required to go through all of the mentioned heat treatment but all steel needs to be treated.
Another heat-treatable metal is stainless steel. For stainless steel, they are generally treated based on the grade or alloy type. Heat treatment methods including hardening, tertekan-relieving, and annealing help to strengthen the corrosion resistance and ductility properties of stainless-steel during fabrication. It also helps to generate a hard structure that can resist abrasion and high mechanical stresses.
The heat treatment of stainless steel is mostly done under controlled conditions to prevent decarburization, carburization, and scaling on the surface of stainless steel. The commonly used methods of heat treatment of stainless steel include annealing (quench annealing, process annealing, and stabilizing annealing), hardening, stress-relieving, and many more.
Titanium and its alloys undergo heat treatment to reduce residual stresses developed during fabrication (Stress relieving). Besides, it leads to the production of an optimum combo of dimensional stability and machinability (Annealing). For increased strength of titanium and its alloy Solution Treating & Aging are used. When it comes to heat treatment, titanium alloys are classified as Alpha, near Alpha, Alpha-Beta, or Beta alloys.While Alpha & near Alpha alloys of titanium can be stress relieved and annealed, the high strength cannot be developed by any type of heat treatmentThe commercial Beta alloys are regarded as metastable Beta titanium alloys. When exposed to selected high temperatures, the retained Beta phase decomposes and strengthening of the material occurs. To obtain Beta alloys, aging and stress relieving treatment can be combined while annealing and solution treatment may be identical operations. As the name implies, Alpha-Beta alloys are two-phase alloys that comprise both Alpha and Beta Phases. They seem to be the most versatile and most common of the three varieties of alloys of titanium.