0
when austenite change into martensite, change in the temprature occurs(cooling). Due to this thermal stress devlop between the core and surface . Surface try to expand and core try to compress the size due to this a change in 'c' parameter take place. So a=b but not=c . this is called BCT stracture.
Wiki User
∙ 10y ago
Add your answer:
Earn +20 pts
What are some uses for martensite?
hardness of martensite is greater than bionite and fine pearlite.
What is generator BCT?
BCT usually stands for bushing current transformer.
Is martensite formed when a steel is quenched?
Martensite transformation begins when austenite is cooled below a certain critical temperature, called the matrensite start temperature. As we go below the tmartensite start temperature, more and more martensite forms and complete transformation occurs only at a temperature called martensire finish temp. Formation of martensite require that the austenite phase must be cooled rapidly.
Hardness of martensite as a function of carbon content?
60*sqrt(C)+20 HRC
What is easier to weld carbon steel or cast iron?
any steel or alloy of iron and carbon having a carbon percentage of above 0.3% is difficult to weld. carbon steel can have maximum carbon percentage of about 2% and cast iron with carbon percentage between 2% to 4%. the welding of any iron alloy with carbon percentage above 0.3% becomes difficult because of the formation of the martensite in the welding areas, heat affected zone etc., the fusion welding process which is usually employed to weld carbon steel and cast iron takes the metal or alloy to their respective melting point (in this case about 1650 C) which is above the austenizing temperature of most steel and cast iron. when the weld is finished it undergoes a process similar to hardening. the nearby non heated parts of the welded material acts as the cold bath resulting in the hardening process which involves sudden cooling for the formation of martensite which is very brittle, any pressure applied will crack the weld immediately. hence before welding the nearby parts of the material to be welded is preheated so that they wont act as any cold bath. but any way cast irons are very difficult to weld than the steels. this is because of the fact that the martensite formed is as a result of trapped carbon atoms in the iron crystal making a distorted body centered tetragonal crystal structure(martensite). higher the percentage of carbon the martensite formation is even better. hence cast irons are especially difficult to weld. design engineers never suggest a welding process for cast iron. cast irons are welded only when there is no other choice but to weld it.
Why martensite is so hard and brittle?
For two reasons: 1. martensite is bct structure which prevent the movement of dislocations. 2. martensite has higher carbon concentraton.
What are some uses for martensite?
hardness of martensite is greater than bionite and fine pearlite.
Why pearlite makes steel harder?
Because Martensite transformation is almost instantaneous, the Martensite has the identical composition of the parent phase. Formation of Martensite involves a transformation from a body-centered cubic structure to body-centered tetragonal structure. The large increase in volume that results creates a highly stressed structure.
What structure forms in hypoeutectoid steel after full hardening?
Martensite
Which is the harder among them Cementite or Martensite?
Martensite
What is lath martensite?
Low carbon content <0.6% results in lath structure as opposed to plate or needle structure for high carbon content >0.6%
When was BCT Commander created?
BCT Commander was created in 2002.
When did BCT Commander happen?
BCT Commander happened in 2002.
What is generator BCT?
BCT usually stands for bushing current transformer.
Is martensite formed when a steel is quenched?
Martensite transformation begins when austenite is cooled below a certain critical temperature, called the matrensite start temperature. As we go below the tmartensite start temperature, more and more martensite forms and complete transformation occurs only at a temperature called martensire finish temp. Formation of martensite require that the austenite phase must be cooled rapidly.
How do you do BCT?
You don't
What is a BCT?
A BCT refers to a brigade combat team - the basic deployable unit of maneuver in the United States Army.
