What does quenching do to a metal?
Quenching improves a metal’s performance by rapidly cooling the heated metal, thereby altering its molecular structure and increasing its hardness. The rate of quenching may be adjusted to achieve the desired properties.
What does quenching and tempering do to microstructure?
The microstructures after quenching and tempering treatment comprise mainly martensite. As the tempering temperature increases, the martensite laths gradually recover. Figure 10(d) shows that the carbides precipitate preferentially along the martensite lath boundaries after being tempered at 570 °C.
What effects did the quenching have on hardness and microstructure?
A variety of steel alloys such as 4140, D2, S7, and O1 were used in the preliminary tests with conventional quenching methods to observe the microstructures and hardness development. Results showed that as the cooling rate of the steel increase, the hardness of the steel increased.
How does quenching affect grain structure?
After the metal is heated, we need to rapidly cool the steel. As material is quenched, the austenitic grain structure created during the heating stage transforms to different grain structures such as martensite, ferrite, pearlite, and cementite.
What do you mean by quenching?
transitive verb. 1a : put out, extinguish. b : to put out the light or fire of quench glowing coals with water. c : to cool (something, such as heated metal) suddenly by immersion (as in oil or water) d : to cause to lose heat or warmth you have quenched the warmth of France toward you— Alfred Tennyson.
How does quenching harden steel?
In metallurgy, quenching is most commonly used to harden steel by inducing a martensite transformation, where the steel must be rapidly cooled through its eutectoid point, the temperature at which austenite becomes unstable.
How does tempering affect microstructure?
The results show that: the microstructure of G18NiMoCr3-6 treated by different tempering processes is tempered sorbite. When tempering temperature is within 510℃ ~630℃, the hardness and strength gradually decrease; the elongation and impact energy gradually increase with the increasing of the tempering temperature.
How does quenching change microstructure?
The rapid quenching changes the crystal structure of the steel, compared with a slow cooling. Depending on the carbon content and alloying elements of the steel, it can get left with a harder, more brittle microstructure, such as martensite or bainite, when it undergoes the quench hardening process.
What happens to microstructure during tempering?
Changes in Martensite Structure The martensite itself also changes during tempering. One change that occurs is that the “tetragonality” of the martensite is reduced as the martensite becomes more and more like cubic ferrite as the carbon leaves the martensite.
Does quenching reduce grain size?
It does this by reducing the window of time during which these undesired reactions are both thermodynamically favorable, and kinetically accessible; for instance, quenching can reduce the crystal grain size of both metallic and plastic materials, increasing their hardness.
How does heat treatment effect microstructure?
The heat treatment develops hardness, softness, and improves the mechanical properties such as tensile strength, yield strength, ductility, corrosion resistance and creep rupture. These processes also help to improve machining effect, and make them versatile.
What is quenching in metalworking?
The blade of a weapon requires an entirely different approach than metal that will be used as bolts on a shipping container, for example. The quenching procedure allows for variations in control that yields the right metal product that the metalsmith is looking for.
Can water be used as a medium for quenching?
Water is an effective medium when the goal is to have the steel to reach maximum hardness. However, using water can lead to metal cracking or becoming distorted. If extreme hardness isn’t necessary, mineral oil, whale oil, or cottonseed oil may be used in the quenching process instead.
Does quenching make steel stronger or weaker?
The diagram that tells you about austenite is called a time-temperature-transformation diagram, or TTT curve. We’ll talk about the TTT diagram later. So, we’ve learned that quenching can make grains smaller, and it can create a stressed, stronger phase. Both of these effects will make the steel stronger but less ductile.
What is the best medium for quenching steel?
Common media for quenching include special-purpose polymers, forced air convection, freshwater, saltwater, and oil. Water is an effective medium when the goal is to have the steel to reach maximum hardness. However, using water can lead to metal cracking or becoming distorted.