the symbol that designates the eutectoid line on a simplified iron-carbon equilibrium diagram

the symbol that designates the boundary between austenite and ferrite + austenite on a simplified iron-carbon equilibrium diagram

the line on the simplified iron-carbon equilibrium diagram that designates the transition from austenite to austenite + cementite 

a process that can occur in which the excess solute atoms precipitate out of the supersaturated matrix to form a controllable nonequilibrium structure upon subsequent heating within the two-phase region

term under which heat-treating operations are classified under. These operations may be employed to reduce strength or hardness, remove residual stresses, improve toughness, restore ductility, refine grain size, reduce segregation, or alter the electrical or magnetic properties of the material 

used in a furnace instead of heat in air to prevent scaling or tarnishing, to prevent decarburization, or to provide surface modification (reduce cost, energy savings, increased safety, and environmental attractiveness)

a process often confused with austempering, it is an example of a thermomechanical process in which deformation and heat treatment are jointly combined, and allows an alloy to benefit with increased ductility of FCC structure, finer grain size upon crystallization of lower temperature and some strain hardening

the process of holding a material at a certain temperature for a sufficient amount of time so that is transforms from austenite to bainite

the crystal structure that changes from face-centered austenite to body centered ferrite, with excess carbon being accommodated in the form of cementite. These carbides are stronger than pearlite, and are ductile because of the soft ferrite.

Shows the results of continuous cooling at various rates.  Used to determine the critical cooling rates required to produce various structures.

the diffusion of carbon into the elevated temperature, face-centered-cubic, austenite structure.  When sufficient carbon has diffused to the desired depth, the parts are then thermally processed. Pg 101

having a constant phase relationship. Pg 87

move the components through the heat-treatment operation at rates selected to be compatible with the other manufacturing operations.

strength obtained from distinct second-phase particles dispersed throughout a base material.

used to indicate both the temperatures that must be attained to produce a desired starting structure and the changes that will occur upon subsequent cooling.  Note: for true equilibrium conditions. Pg 83

uses an oxyacetylene flame to raise the surface temperature high enough to reform austenite.  The surface is then water quenched and tempered to the desired level of toughness.  Heat input is quite rapid and is concentrated on the surface.  Slow heat transfer and short heating times leave the interior at low temperature and therefore free from any significant change.

these furnaces consist of a bed of dry, inert particles, such as aluminum oxide, which are heated and fluidized (suspended) in a stream of flowing gas.  Products introduced into the bed become engulfed in the particles, which then radiate uniform heat.  Temperature and atmosphere can be altered quickly, and high heat- transfer rates, high thermal efficiency, and low fuel consumption have been observed.  Since atmosphere changes can be performed in minutes, a single furnace can be used for nitriding, stress relieving, carburizing, carbonitriding, annealing, and hardening.

when hypoeutectoid steels are heated to 30 to 60 degrees C above the A3 temperature, held for sufficient time to convert the structure to homogeneous single-phase austenite of uniform composition and temperature, and then slowly cooled at a controlled rate to below the A1 temperature. The resulting structure is one of coarse pearlite (widely spaced lamellae) with excess ferrite in amounts predicted by the phase diagram.  In this condition, the steel is quite soft and ductile.

process that makes grains smaller in metal, one of the few processes that can simultaneously improve both strength and ductility.

a measure of the depth to which full hardness can be obtained under a normal hardening cycle and is related primarily to the amounts and types of alloying elements.

a mechanical property related to strength and is a strong function of the carbon content of a steel.

the controlled heating and cooling of metals for the purpose of altering their properties.

a base metal dissolves other atoms in solid solution.

- involves heating to a temperature above the solvus, thereby replacing the starting room-temperature structure with an elevated temperature single-phase solid solution.  This is the first step in precipitation hardening.

When high-carbon steels (>0.60% carbon) are to undergo extensive machining or cold-forming.

- produces an increase in strength by means of plastic deformation under cold-working conditions.

may be employed to reduce the residual stresses in large steel castings, welded assemblies, and cold-formed products.

where new atoms occupy sites in the host crystal lattice.

treatment of steel by heat or mechanical means to increase the hardness of the outer surface while the core remains relatively soft. 

Quenching steel to form 100% martensite and then tempering it at various temperatures, an infinite range of structures and corresponding properties can be produced.

Subsequent heating that is usually required to impart the necessary ductility and fracture resistance.

Where deformation and heat treatment are intimately combined.