how to produce martensite

1. NAME : THIRUNAVUKARASU.H
13MY12
MARTENSITIC STAINLESS
STEEL

2. Martensitic stainless steel
 High hardenable steels ductile in nature ductility
is subjected to the maximum hardness w.r.t
tempering
 Cr=15-25%
 Hardness of the stainless steel depend on carbon
content
 Quenching rate is depend on martensite phase
formed
 Development of martensite phase is assisted with
increase in corrosion

3. series alloys
 400 series alloys, including 410, 420 and 440 are
martensitic stainless steel alloys.

4. MARTENSITE
 Martensite refers to a very hard form of steel
by diffusion less transformation.
 It includes a class of hard minerals occurring as
lath- or plate-shaped crystal grains.
 needle-shaped

5. Formation of martensite
 Martensite is formed in carbon steels by the rapid
cooling (quenching) of austenite at such a high
rate that carbon atoms do not have time to diffuse
out of the crystal structure in large enough
quantities to form cementite (Fe3C)
 As a result, the face centered cubic austenite
transforms to a highly strained body centered
cubic form of ferrite that is supersaturated with
carbon.

6. Hardness
 The highest hardness of a pearlitic steel is
400 Brinell whereas martensite can achieve
700 Brinell

7. Condition to form martensite
 The martensitic reaction begins during cooling
when the austenite reaches the martensite start
temperature (Ms) and the parent austenite
becomes mechanically unstable. As the sample is
quenched, an increasingly large percentage of
the austenite transforms to martensite until the
lower transformation temperature Mf is reached,
at which time the transformation is completed

9. Retained austenite
 For a eutectoid steel, between 6 and 10% of
austenite, called retained austenite, will remain.
The percentage of retained austenite increases
from insignificant for less than 0.6% C to 13%
retained austenite at 0.95% C and 30–47% for a
1.4% carbon steels

10. Heat treatment sub zero

11. Properties
 Martensitic alloys contain lower amounts of
chromium (between 12-14%) and are less
corrosion resistant than austenitic and ferritic
alloys. Their properties include:
 Extreme strength and toughness
 Can be work-hardened
 High machinability and workability to tight
tolerances
 Smooth surface finish

12. APPLICATIONS
 A sample of the products that are manufactured using
stainless steel includes:
 Pots, pans, flatware and utensils
 Kitchen and restaurant equipment
 Sinks and drains
 Fittings, clamps and connectors for sanitary and
processing applications
 Tanks, tubing, piping for sanitary, foodservice
chemical and petrochemical processing
 Automotive components
 Enclosures, housings and cabinets
 Springs