Heat treatment Flashcards
XRD
X ray Diffraction. Read wavelenght to determine grain size and different phases
Quenching
The procces where metal is cooled in some type of solution at a fast cooling rate. cooled through it’s eucteoid point.
Temperature gradient
change in temperature
Tempering
The procces to change the tempeture to increase toughness. rapid cooling
Stress Relieve
Procces where you heat up to recyrazatioln and then cool down. Used to remove the different stresses, residual stresses, and inertial stresses as well as distortion.
Hot rolling
Heated at recryzalation tempeture and then strecthed out to be put through two rollers. rolled out
Surface Hardening
Proccess where the surface is treateeted to create a thin, wear resistance layer with increased harndess . the core remains soft and ductile . Done to increase hardness
Homogenizing
Procces to reduce chemical segregation one element. allows for chemical diffusion involves heating near the metling point and then slowly cooling it.
Spherodizing
results in nodules in grains turningign into spheres. results in high ductility.
Normalizing
Done outside of the furnace. Increases formability.
Ovens
Air ducts distribute heated air from separate heating chamber via recirculating fan. best at lower temperatures
Annealing
The process involves heating the metal so that the metal as well as rearranges the structure of the metal. . Done to increase ductility.
Quenching medium
The liquid material into which metal is plunged during the quenching. Process
4 stages of quenching
Steam forming. Steam coverage. Steam
Surface Hardening
Pro
4 stages of vapor film
4 stages of quenching decreases temperature throughout.
Steam formation: metal I. The beaker metal starts to cool. forms a vapor field.
Steam coverage: covered in a cloud of vapor or steam blanket. Bubbles stick to the metal and consulate if from the quenching medium.
Steam discharge: a discharge where the film of bubbles collapses. Allows the metal to again make contact with the quenching medium. Agitation can decrease time in this stage. Very violent.
Slow cooling: cools at a slower cooling rate to a normal rate. No more vapor film.
Process’s of Martempering
put in a molten salt booth just above it’s martensite start tempt. The quench is much less severe. Partial quench, hold, finish quench,reheat, hold, then quench. are done to minimize residual stress, distortion, and cracking.
Proccess of Austempering
ss
Product of Martempering
Tempered Martensite
Thermal location Dislocation
Raise the temperature to rearrange the position of atoms in the crystal structure.
Raise the temperature in tempering
will decrease yield strenght, and tensile strenght.