What is used for quenching?
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.
What is the purpose of tempering?
Tempering, in metallurgy, process of improving the characteristics of a metal, especially steel, by heating it to a high temperature, though below the melting point, then cooling it, usually in air. The process has the effect of toughening by lessening brittleness and reducing internal stresses.
What happens during tempering?
During the tempering process, the carbon atoms move out of the spaces between the iron atoms in the martensite to form the iron carbide particles. The strain within the martensite is relieved as the carbon atoms move out from between the iron atoms in the martensite.
What is Normalising steel?
Normalising consists of heating a suitable steel to a temperature typically in the range 830-950°C (at or above the hardening temperature of hardening steels, or above the carburising temperature for carburising steels) and then cooling in air.
What is the advantage of quench hardening?
Lessening Metal Part Distortion Slower and more uniform cooling of parts is possible using higher quench media temperatures as the quenching heat treatment process is performed. This process also allows for a more uniform transformation during hardening.
Is it better to quench in oil or water?
Water is one of the most efficient quenching media where maximum hardness is desired, but there is a small chance that it may cause distortion and tiny cracking. When hardness can be sacrificed, mineral oils are often used. The cooling rate of oil is much less than water.
What are the disadvantages of quenching?
Single liquid quenching: heating the steel to quenching temperature, and cooling in a quenching agent (water, salt water or oil), is called quenching. The advantage is that method is simple so it’s widely applied. The disadvantage is that the internal stress is large so the steal is prone to crack or deformation.
What oil is best for quenching steel?
Mineral oil quenchants work great with steels that require a fast quench rate and oil-hardened steels. Mineral oils generally have greater cooling capacities for steel alloys. Their efficiency in the quenching process increases their overall cost.
Can you quench steel in water?
Water is able to quench heated metals rapidly as well. It can cool a metal even faster than oil.
Why annealing is expensive?
Full annealing consists of heating steel to above the upper critical temperature, and slow cooling, usually in the furnace. Long cycle times are required to do this with many high alloy steels and it is therefore expensive.