What is austempering and martempering process?
The two processes are heating a medium-to-high carbon ferrous metal to an austenitic condition then cooling the object rapidly enough to avoid the formation of pearlite to a temperature above temperature and isothermally holding the part for a time sufficient to produce the desired microstructure.
What is a benefit of martempering over a regular quick quench?
The primary advantage of martempering is that parts will have lower distortion and reduced residual stress. This is from reduced thermal gradients during quenching and relatively uniform transformation of martensite. Martempering can be accomplished in either oil or molten salt.
What are the advantages of austempering process?
The advantages of austempering include higher ductility at high hardness, increased strength and ductility at a given hardness, greater fatigue life and less distortion and cracking.
What is the purpose of hardening and tempering?
Hardening and tempering develops the optimum combination of hardness, strength and toughness in an engineering steel and offers the component designer a route to savings in weight and material.
What is the purpose of martempering?
Marquenching/Martempering is a form of heat treatment applied as an interrupted quench of steels typically in a molten salt bath at a temperature right above the martensite start temperature. The purpose is to delay the cooling for a length of time to equalise the temperature throughout the piece.
What happens in martempering?
Martempering is also known as stepped quenching or interrupted quenching. In this process, steel is heated above the upper critical point (above the transformation range) and then quenched in a salt, oil, or lead bath kept at a temperature of 150-300 °C.
What is austempering in heat treatment?
‘Austempering’ is the process of heat treatment where the steel is heated to austenitizing temperature, held there for sufficient period of time to produce homogeneous austenite.
What are the advantages of the austempering process What are the disadvantages?
Advantages include higher ductility at high hardness, increased strength and ductility at a given hardness, increased toughness (over 40 HRC), greater fatigue life and less distortion and cracking (especially in higher carbon steels). Limitations include section size and carbon level (for a given steel).
What is the purpose of normalizing heat treatment for steel?
Normalizing heat treatment helps to remove impurities and improve ductility and toughness. During the normalizing process, material is heated to between 750-980 °C (1320-1796 °F). The exact heat applied for treatment will vary and is determined based on the amount of carbon content in the metal.
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 is purpose of hardening?
Hardening is a metallurgical metalworking process used to increase the hardness of a metal. The hardness of a metal is directly proportional to the uniaxial yield stress at the location of the imposed strain. A harder metal will have a higher resistance to plastic deformation than a less hard metal.
What is Austempering in heat treatment?