Mechanical Engineering & Documents

Annealing is a opposite process of hardening process . Why annealing process have to perform :  Relieve internal stress Soften material Increase ductility Refine the grain structure Process : Material is heated above the re-crystallization temperature and hold material at specific temperature and time. And last material is cool at room temperature. Cooling process is depend upon the metal and required properties. Usually material are cooled inside the furnace. Also material is cooled by burying them in ashes, lime, or other insulating materials.

Difference between Annealing & Tempering is as per below. Annealing Tempering Annealing is a primary process. Tempering is a secondary process. Usually done after hardening process. Material is heated above re-crystallization temperature. Material is heated below re-crystallization temperature. Cooling process of material is take place inside the furnace. Cooling process of material is take place outside the furnace. Please let me know if there is a any query or want to add points.

E book: Treatise on Thermodynamics Download PDF file from here .

Tempering is process use to increase toughness of metal. This process is perform on iron based material and usually used after hardening process for reducing excess hardness. This process is done by heating metal below critical point and usually cool by air. There are some steel that are quenched after tempering process for avoiding brittleness. Tensile strength of harden steel may increase when tempering process is done about 450°F. And above this temperature it decrease. Hardness is reduce according to temperature at which tempering process done. Note : Only for high-speed steel material, hardness is increase during tempering process about temperature 1550 °F . Minimum time required for 1 mm thick material for tempering process is : 1 Hour. Time increase for every addition of 1 mm is : 1 Hour. Tempering increases softness, ductility, malleability, and impact resistance.

E book : Thermodynamics by Yunus and Michael Download PDF file from here .

Case hardening is type of Hardening Technique . Case hardening is Heat Treatment process which is use to harden the upper layer of material while allowing inner layer soft. Upper layer is become harder as per material requirement. In this process, only upper layer become harder so this process is also known as Surface Hardening Process . Case hardening process is use to harder top layer or limited depth from top layer. Types of Case or Surface Hardening Process: Carburizing Cyaniding Nitriding

Hardening is a one of the technique of Heat Treatment Process . Use of this treatment process is to improve mechanical properties, hardness, durability. Hardening process is usually use for steel material . Working of Process: Steel material is heated up to set temperature, then cooling it to rapidly by using water, oil or brine. Most steel material is cooled by rapidly but some material can be air cooled. Types of Hardening Process: There are two types of hardening process. Case Hardening Process Flame Hardening Process

Heat treatment is a process in which heating and cooling of a metal or alloy is done in order to obtain desirable characteristics by changing physical and mechanical properties without changing its shape. Purpose of heat treatment process is to obtain desired hardness, formability, machinability etc. This process is also use to improve product performance, lifetime and so many characteristics. Type of Heat Treatment Process or Technique of Heat Treatment Process: Hardening Tempering Annealing Normalizing Carburizing Case Hardening Stress Reliving Quenching

It is impossible by any procedure, no matter hoe idealized, to reduce any system to absolute zero temperature in a finite number of operations.

Kelvin plank Statement It is impossible for a heat engine to produce net work in a complete cycle if it exchanges heat only with bodies at a single fixed temperature. Two reversible adiabatic parts cannot intersect each other which violates the Kelvin-Plank;s statement. The machine which violate Kelvin plank statement is called PPM2 (Perpetual Motion Machine of Second kind). Clauses Statement It is impossible to construct a device which operating in a cycle transfers heat from cooler body to a hotter body without any work input.

First law of thermodynamics is stats that energy cannot be created or destroyed, but only changed from one from into another or transfer from one to other. OR For a cycle or closed system, any change in internal energy can be accounted as the difference in heat accumulated and work done by it.

When a body A is in thermal equilibrium with a body B & also separately with a body C then body B & C will be in thermal equilibrium with each other. Zeroth law of thermodynamics is the basis of temperature measurement.