Step 1: The document summarizes a presentation given by Dr. Ramaswamy Narayanasamy on the formability of deep drawing grade steels. Step 2: It provides details of the speaker's achievements and scientific contributions related to sheet metal forming and formability studies on various steel grades. Step 3: The presentation describes the methodology used to construct forming limit diagrams (FLDs), including the different strain conditions tested, grid circle marking on sheet specimens, measurement of strain after deformation, and plotting of the FLD curves.

1. PRESENTATION ON FORMABILITY OF
DEEP DRAWING GRADE STEELS & OTHERS
FOR JINDAL STEEL PLANT
Presented
by
Dr. RAMASWAMY NARAYANASAMY
B.E.,M.Tech.,M.Engg.,Ph.D.,(D.Sc)
Fellow of Indian Institute of Metals
Retired Professor (HAG)
National Institute of Technology
Tiruchirappalli 620 015
Tamil Nadu

2. ACHIEVEMENTS
SCOPUS INTERNATIONAL RANKINGS (Scopus ID: 7004243469)
a) Sheet Metal Forming Rank - 3
b) Formability Rank - 3
c) Wrinkling Behavior of Sheet Metals Rank - 1
d) Forming Limit Diagram of Sheet Metals Rank - 1
e) Fracture Limit Diagram of Sheet Metals Rank - 1
f) Workability Rank - 6
g) Strain Hardening Rank - 3
h) Forging Rank - 8
i) Upset Forging Rank - 1
AWARDS RECEIVED
1. International Best Scientist Rank on Materials (Top 2%) – by Stanford University, USA
2. Tamil Nadu Scientist Award for Engineering and Technology – 2008
3. Best Teacher Award 2006-2007 – NIT Trichy

3. MAJOR SCIENTIFC CONTRIBUTIONS
 TUBE INVESTMENT OF INDIA
 McMaster University, CANADA
 TATA STEEL
 FORD MOTORS
 SALEM STEEL PLANT ( SAIL )
 JINDAL STAINLESS STEEL PLANT
 HEAVY ALLOY PENETRATOR PROJECT (HAPP-Defence),Trichy
 NATIONAL AEROSPACE LABORATORY, BANGALORE
 Other scientific works in NIT-Trichy

4. For plastic deformation shear stress is required
𝜏 𝑚𝑎𝑥 =
𝜎 𝑚𝑎𝑥 − 𝜎 𝑚𝑖𝑛
2
In triaxial state of stress system,
shear components are
(𝜎1− 𝜎2), (𝜎2− 𝜎3) and (𝜎3− 𝜎1)
Taking root mean square value and equating to uniaxial
stress condition,
The yield equation can be obtained
൯( 𝜎1 − 𝜎2
2
+ ൯( 𝜎2 − 𝜎3
2
+
൯( 𝜎3 − 𝜎1
2
= 2 ቁ( 𝜎y
2
𝜎 𝑦 = Yield stress in uniaxial tension

5. The above equation can be written as
൯( 𝜎1 − 𝜎2
2
+ ൯( 𝜎2 − 𝜎3
2
+ ൯( 𝜎3 − 𝜎1
2
= 𝜎2
Where σ is the effective stress
For plane stress condition
The equation becomes
𝜎1
2
+ 𝜎2
2
− 𝜎1 𝜎2 = 𝜎2
For anisotropic sheet metal, the above
equation becomes
𝜎1
2
+ 𝜎2
2
−
2𝑅
𝑅 + 1
𝜎1 𝜎2 = 𝜎2
Where R is plastic strain ratio

6. The equation is nothing but an ellipse
Yield Locus
Hydrostatic stress + compression in thickness direction = Equi biaxial stress
Hydrostatic stress
It has no shear stress
component
R = 0

7. Therefore, the compression through thickness direction controls
Equi biaxial stress.
Hence, R>1 major axis of ellipse increases
R<1 major axis of ellipse decreases.
With this idea I.F. steel has been developed.
In the case of conventional I.F. steel R = 1.8 or more

8. Mohr’s Circle: Uniaxial tensile test
t max
s
s2 = s3 = 0
s1 is present
t

9. t
maxs3 =
0
Mohr’s Circle: Equi biaxial stretching
t
s
t max
s1 = s2
Say s3 =0
s1 Biaxial > s1Uniaxial
Yield stress increases in equi biaxial stretching compared to
uniaxial loading

10. t
max
Mohr’s Circle : Deep draw test
s2 s1
s
t
t max = is more (increases)
s 1 is tensile
s2 is compressive
t max uniaxial <t max biaxial <t max deep draw
s 3 is zero

11. Mohr’s Circle for Deep Draw
• In radial direction stress is tensile .
• In the hoop direction stress is compressive.
• Hence, shear stress is greater.
• Therefore, larger deformation is possible
compared to uni axial or equi biaxial tensile
test.

14. Steps for Forming process
Fig. 5. SS 430 grade sheet metals:
A) Batch annealed, B) Continuous
annealed, C) Cold rolled
Sheet dimensions for various strain
conditions
Tension – Tension strain condition:
300 mm x 220 mm,
300 mm x 200 mm,
300 mm x 180 mm,
300 mm x 160 mm,
Plane Strain condition:
300 mm x 140 mm
Tension – Compression strain
condition
300 mm x 120 mm,
300 mm x 100 mm,
300 mm x 80 mm,
300 mm x 60 mm

15. Steps for Forming process

16. Step 1: Strain conditions, namely, tension–tension, plane strain, and
tension–compression were considered by varying the width of
specimen, which plays an important role in determining the Forming
Limit Diagram (FLD).
Step 2: The grid circles formed over the sheet specimens, which were
stretched to form ellipses depending upon the straining condition.
Steps to construct Forming limit diagram
Fig. 6. Forming Limit Diagram (FLD).

17. Step 3: The major and the minor axes of the ellipse were
measured using the microscope with an accuracy of 0.01 mm,
which has taken for plotting forming limit diagrams.
Step4: These manual measurements were used to calculate the
major strain and minor strain.
Steps to construct Forming limit diagram
Fig. 7. Microscope

18. Step 5:
Steps to construct Forming limit diagram

19. Steps to construct Forming limit diagram
Step 6: These strains were measured in three distinct regions
like safe region, neck region and fracture region.
Step 7: The forming limit diagrams were plotted using strain
measured at necked regions, whereas, the Fracture limit
diagram uses strains from fractured regions.
Step 8: Similarly, Fracture limit curve has been plotted using
strains obtained from fracture region of all width specimens.

20. Combined forming, fracture and wrinkling limit
diagram

21. Fig. 8. Schematic representation of combined
forming and fracture limit diagram
Fig. 9. Forming limit diagram for Continuous
annealed (CA), Batch annealed (BA) and Cold
rolled (CR) SS 430 sheet metals

23. WORKS CARRRIED OUT IN TUBE INVESTMENTS OF INDIA
(1979-1981)
a) FLD(Forming Limit Diagram) and Wrinkling behavior of different steels
sheet metals, Tube Products of India, Chennai, India, Co-ordinator (2003)
b) Processing of Al, Ti and Boron killed EDD quality steels for automotive
applications (1979-1981)
c) Grain growth in low carbon steels (1979-1981)
d) Processing of low and high silicon steels for electrical industries
e) Processing of Rimmed, Semi killed and killed low carbon steels for
automotive applications
 During processing of steels, by controlling annealing parameters and cold
rolling percentage the required properties were obtained
 Outcome / Observation : Aluminium killed EDD quality steel supplied by
TATA Steel showed better performance during Cupping Test.

24. Effect of temperature and time on Austenitic
grain size

25. The Pinning effect of second phase particle on
grain boundary

26. The effect of Aluminum addition on Nitrogen
Al + N AlN
In the case of Ti, Nb and B addition gives respective
nitrates and carbides
Nb+ N NbN
Nb+ C NbC

27. The effect of Temperature on Austenitic grain
size
ASTM Grain size Number
8 – represents fine grain size
1 – represents coarse grain size
Fine grain size inhabits grain
growth at lower rate
compared to coarse grain size

28. The effect of aluminum content in steel on grain
coarsening temperature

29. The effect of Al N second phase particle as a
function of temperature

30. The effect of micro alloying addition on
Austenite grain size

31. McMaster University, CANADA (1981-1983)
 Studied on wrinking behaviour of various steels supplied by Inland Steel
Corporation, USA and Dofesco Steel Plant, Hamilton, Ontario, Canada
 Used Conical and Tractrix Dies for deep drawing with no hold down pressure.
 Steels Tested : Steels tested were stainless steel 304 grade, Dual phase steel and
Aluminium killed extra deep drawing quality steel with different thicknesses.
 Outcome : Steel with high normalized hardening rate and high instantaneous strain
hardening exponent exhibited more resistance against wrinkling.
In the case of stainless steel 304 grade, because of the formation of plastically
strain induced martensite during deformation exhibited high resistance against
wrinkling.
 Dual Phase Steel (600MPa) exhibited poor resistance against wrinkling because of
poor instantaneous strain hardening exponent and normalized hardening rate.

32. TATA STEEL (2006-2010)
Steels Tested :
Conventional I.F. Steel, High Strength I.F. Steel, Carbon Manganese Steel,
Microalloyed Steel, HSLA Steel, Galvannealed Steel, Coated Steels and
Nano Precipitate High Strenth Steels for various Automotive
applications.
Results :
Tested for Forming limit diagram, Void Coalesence sudies on fractured
samples and hole expansion test.

33. TATA STEEL
Microstructure of Steels
IF Microalloyed Steel C-Mn Steel
High Strength IF Steel
10 mm

34. CHEMICAL COMPOSITION AND ITS EFFECT
In the case of IF steel a small amount of Nb and Ti is added. This addition converts
carbon and Nitrogen into Niobium carbo nitrates and Titanium carbo nitrates.
In high strength IF steel, in addition to Nb and Ti, a small amount of Boron is added
to take care of the precipation of Iron Phosphide along grain boundaries.
In IF steel, the carbon and nitrogen are in PPM level.
In C-Mn steel : Carbon is 0.12 % and Mn is 1.8 %.
In C-Mn steel, the carbon equivalent is high and it is not suitable for spot welding.
Microalloyed Steel : Here, C is less than 0.1% and a small amount of Nb is added
which increases the strength.
Microalloyed steel is suitable for spot welding.
For conventional IF steels Rav is 1.8. For high strength IF Rav is 1.4.

35. CONSTRUCTION OF FORMING LIMIT DIAGRAM

36. FORMING LIMIT DIAGRAMS ( IF Steels )
0.6 mm thick 0.9mm thick
1.2mm thick 1.6 mm thick

37. Strain Path/
Strain Ratio
Limiting Major Strain
T-T 0.6 mm 0.9 mm 1.2 mm 1.6 mm
1 /0.37 41.5 43 52.5 52.5
2 / 0.283 43 43 55.5 53.5
3 / 0.176 39 40 52 49
Plane
4 / 0 31 32 36 35
T-C
5 / -0.093 33 36 39 40
6 / -0.16 36 40 44 47
7/ -0.233 42 47 60 70
%

38. EXPLANATION FOR FORMING LIMIT DIAGRAMS ( IF STEELS )
High Normal Anisotropic value (Raverage) increases the forming limits
in T-T, P-S and T-C regions.
Usually 90 % cold reduction must be given for high Normal
Anisotropic value.
High strain hardening exponent value (n-value) increases the
Forming Limits.
High strain rate sensitivity (m-value) increases the Forming Limits.
High thickness increases the forming limit for any given
microstructure and processed conditions.
 Gamma Fibre Texture improves the formability

39. Forming Limit Diagram for High Strength Steels
Microalloyed Steel 1.2 mm thick C-Mn Steel 1.4 mm thick
The forming limits for both Nb treated microalloyed steel
and C-Mn steel are almost same.

40. SEM IMAGES FOR C-Mn and Microalloyed Steels:
C-Mn 120 mm blank (T-C) C-Mn 140 mm blank(P-S) C-Mn 200 mm blank (T-T)
Microalloyed Steel: Microalloyed steel exhibits smaller voids compared to C-Mn Steel

41. Fracture behavior – Void coalescence analysis
• The fracture and material void behavior are influenced by the strain
condition.
• During the forming operation, initiation of necking would occur
following the void nucleation, the void growth and the void
coalescence.
*https://www.thefabricator.com/article/aluminumwelding/aluminum-workshop-charpy-v-
notch-testing-why-not-aluminum-
Fig.1. Schematic representation of occurrence
of void coalescence

42. Fracture behavior – Void coalescence analysis
• The fracture and material void
behavior are influenced by the
strain condition.
• Variations in void size, void area
are clearly visible in the shown
SEM image for the various
strain conditions namely,
Tension – Tension, Plane strain
and Tension - Compression
Fig.2. SEM fracture surface morphology of cryorolled AA5052
obtained after forming operation near the fracture zone.

43. The void coalescence parameters can be
correlated with formability.
The parameters are:
(i) Void size
(ii) Void area fraction =
𝑇𝑜𝑡𝑎𝑙 𝑎𝑟𝑒𝑎 𝑜𝑓 𝑣𝑜𝑖𝑑
𝑅𝑒𝑝𝑟𝑒𝑠𝑒𝑛𝑡𝑎𝑡𝑖𝑣𝑒 𝑚𝑎𝑡𝑒𝑟𝑖𝑎𝑙 𝑎𝑟𝑒𝑎
Representative material area is the total
area of the voids present in the chosen
area.
(Ex. Total number of voids in 1 inch2 SEM
image area)
(iii) Ligament thickness (gap between two
adjacent voids)
(iv) d-factor (ratio of ligament thickness to
the radius of void)
(v) Aspect ratio of void (L/W).
Ligament thickness
Dimples
Void size
Void coalescence
Void size, Void area and other void coalescence parameters
Fig. 3. SEM fracture surface morphology of cryorolled AA8090

44. Void size, Void area and other void coalescence parameters

45. Correlation of Void coalescence analysis
with formability
• Higher average void size value and higher void area fraction
percentage indicates better formability.
• The lower ligament thickness value is an indication of
accumulation of enhanced plastic deformation.
• A lower d-factor signifies increased formability.

46. Step 1: The samples were cut close to the fracture zone for SEM
analysis to observe the nature of the fracture.
Step 2: Average void sizes were obtained from the SEM images using
AutoCAD software.
Step 3: Using Auto CAD software, the SEM images were enlarged and
voids were identified to measure perimeter of void, the average value of
perimeter of voids become the average void size.
Step 4: Relative spacing of the ligaments between two consecutive voids
is measured using line command.
Step 5: Similarly using line command, the length and width of the void
is measured.
Step 6: Void area fraction is determined using the following relation
Void area fraction =
𝑇𝑜𝑡𝑎𝑙 𝑎𝑟𝑒𝑎 𝑜𝑓 𝑣𝑜𝑖𝑑
𝑅𝑒𝑝𝑟𝑒𝑠𝑒𝑛𝑡𝑎𝑡𝑖𝑣𝑒 𝑚𝑎𝑡𝑒𝑟𝑖𝑎𝑙 𝑎𝑟𝑒𝑎
Steps to find the void size, void area and other void coalescence
parameters using Auto CAD software

47. Fig.4. Void coalescence parameters with respect to strain triaxiality (εm/εeff) for Al-Mg-Sc
alloy rolled at (a) Room temperature with 50 % reduction, (b) Cryogenic temperature with 50
% reduction.

48. •Void size (VS) values of the CR sample are noted to be marginally lower than RTR
sample.
• Void area fraction (VA) is observed to be higher for RTR sample than that of CR
sample.
•The d-factor (ligament thickness/ radius of void) and ligament thickness (LT) are
higher for CR sample than RTR sample.
•The lower LT is an indication of accumulation of enhanced plastic deformation and
a lower d-factor signifies increased formability.
•The (L/W) ratio is also noted to be decreasing with respect to the given strain
triaxiality value.
•The L/W ratio indicates the nature of void (either prolate or oblate) and based on
the state of applied stress the void may get modified to prolate (elliptical voids in the
vertical direction) or oblate (elliptical voids in the horizontal direction) from its
initial spherical nature.
•Oblate and spherical voids tend to grow faster than prolate voids. (L/W) is higher
for CR samples than RTR samples.

49. SALEM STEEL PLANT (SAIL -2010): OUTCOME
 The void area fraction (Va) is found to be higher for SS 304 steel sheet due to
the presence of lesser amount of carbides and sulphides and thus exhibits
better formability and fracturre strain than the rest of the sheets.
 In addition to that SS 304 steel sheet shows lower L/W ratio and exhibits
better formability and fracture strain. The formability of SS LN1 is
comparable with SS 304
 The higher value in volume fraction of Goss component indicates low
formability in the case of SS 430
 The sheets of SS 430 have lower nR-value which leads to inferior formability
 On the other hand, SS 304 and SS LN1 show better formability because of
phase transformation during plastic deformation.

50. WRINKLING OF SHEET METAL DURING DEEP DRAWING

52. NATIONAL AEROSPACE LABORATORY, BANGALORE
Tested Aluminium alloy :
Al-3% Mg-0.2% Sc alloy
OUTCOME :
 Cryorolled and tested for Forming Limit Diagram.
 Greater amount of diffuse necking has been absorbed.
 Larger amount of fracture strain has been observed.
 Strength has been increased after cryorolling.
 More ultrafine and some nano size grains has been observed.

53.  Samples of the size of 10 х 10 (length х
width) mm were cut from the surface
 The samples were mechanically polished and
then electro polished (Struers-Electropol™-
IV,USA) in a cryo electrolyte containing 80:20
methanol and perchloric acid at −16 °C with an
operating voltage of 16 V for the duration of 20s.
 The EBSD measurements were performed at the
center of the samples. A step size of 0.1 μm was
used during the measurements. TSL OIM
analysis 4.6 software (TEXSEM Laboratories
Inc., Draper, Utah, USA) was used to analyze the
EBSD maps. Based on the EBSD analysis the
grain size distribution and their volume fractions
were analyzed along with Kernal average
misorientation (KAM)
EBSD - FEITM Quanta – 3D FEGSEM
Fig. 1. Struers-Electropol
Procedure for EBSD (Microtexture)
Fig. 2.

54. Outcomes of EBSD (Texture Study)
Inverse pole figure maps
 A (scanning) electron microscopy technique which measures
crystal orientations on a regular grid by electron diffraction.
 The so-determined data are used to produce orientation or phase
maps of the scanned area on the sample.
 By assigning similar colours to points with similar crystal
orientation or similar phases. In this way orientation maps are
obtained.
Grain boundary maps
 By determining the change of
orientation from position to
position, misorientation maps can
be produced as well.
 Besides a large variety of different
maps it is also possible to construct
statistical data sets from the sample,
for example orientation
distributions.

55. Fig. 3. Inverse pole figure maps (IPF) of Al-Mg-Sc alloy: (ai) base alloy, (bi) R50, (ci) C50,
(di) R75 and (ei) C75.
 Hierarchical grain size distribution with few nano sized grains, ultra fine
grains and coarse grains are noted in the cryorolled samples of Al-Mg-Sc
alloy.
Results of Micro Texture
Notations
R50 –50% thickness reduction attained by room temperature rolling
C50 –50% thickness reduction attained by cryorolling
R75 –75% thickness reduction attained by room temperature rolling
C75 –75% thickness reduction attained by cryorolling

56. Fig. 4. EBSD - grain size distribution plot for: (aii) base alloy, (bii)
R50, (cii) C50, (dii) R75 and (eii) C75
Results of Micro Texture
 The cryorolled sample exhibits
reduced average grain size.
 More fraction of UFGs are observed
in the cryorolled samples

57. Results of Macro Texture
Table 2. Mechanical anisotropy and texture indices of base alloy, R50, C50, R75
and C75 of Al-Mg-Sc alloy
Process
condition
Texture
index
Base alloy 11.43
R50 9.06
C50 8.95
R75 2.83
C75 3.37
 The texture index is considered to be proportional to the
intensity of texture that has been developed in the material
and the higher 𝑇𝐼 indicates that the particular material is
highly anisotropic as meant by Bunge (1982).
 The reduced 𝑇𝐼 value in C75 sample indicates that the
material is less anisotropic.
As the 𝑇𝐼 decreases, the fracture limit increases and
formability limit decreases in cryo rolled Al Alloys
For lower misorientation angle grain boundary, higher
formability can be obtained.

58. PROPOSED WORK FOR JINDAL STEEL PLANT
 Enhancement of Quality of Deep Drawing grade Steels in
Automotive Sector
 Development of Dual Phase and Multiphase Steel for Automotive
Applications

59. Enhancement of Quality of Deep Drawing grade Steels In
JINDAL STEEL Plant For Automotive Applications
 Studies on the following :
Forming Limit Diagram
Wrinkling Limit Diagram
Void Coalescence Study
Fracture Limit Diagram
Hole Expansion Test
Texture Study ( Micro and Macro)
Tensile Property Study
 Tensile Properties :
Yield Strength, Tensile Strength and Ductility
Establishment of material law (k and n values determination)
Tangent Modulus Value
Normalized Hardening Rate
Instantaneous Strain Hardening Exponent Value
Instantaneous Strength Coefficient Value
Normal Anisotropy and Planar Anisotropy Values
Based on these above parameters, the forming limit, the wrinkling limit, fracture limit
and hole expansion limit can be studied and the quality of steel can be improved.

60. Recrystallization Temperature Variables.
• Higher cold rolled reduction – fine grain.
• Lower Tre Temperature – fine grain.
• Lower recrystallization time – fine grain.
• If recovery is slow, recrystallization will be faster.
• Pure metal – reduces the Tre
• Higher cold reduction – reduces Tre

61. Manufacturing of High Strength Multiphase / Dual Phase Steel
MELTING
Heat Transfer
&
Solidification
Weldability
Study
Hot Rolling of Ingots
& Plates
Machinability
Study
Heat Treatment
Formability
Study

62. DEVELOPMENT OF HIGH STRENGTH
MULTIPHASE / DUAL PHASE STEEL
GROUP Members
Melting JINDAL Steel Group
Heat Transfer and Solidification 1.Dr.P.Srinivasan, BITS – Pilani
2.Dr.Venkateswaran, BITS-Pilani
Hot Rolling 1. Dr.S.Venugopal, Retd. Scientist,
IGCAR, Kalpakkam, Tamil Nadu
2. Dr.R.Narayanasamy, NIT-Trichy
Heat Treatment Dr.R.Narayanasamy, NIT-Trichy
Formability Studies Dr.R.Narayanasamy, NIT-Trichy
Weldability Studies Dr.K.Siva Prasad, NIT-Trichy
Machinability Studies Dr.V.Sivaraman, Formerly IIT Madras

63. DEVELOPMENT OF MULTIPHASE STEEL
Processing Map for Hot Rolling
 The dynamic materials model processing and instability maps will be
generated
 For optimising the processing parameters such as roll speed, reduction per
pass and temperature of the billets for hot rolling.
 These processing maps will be applied for controlling the development of
microstructure
 Initial billet microstructure – Processing microstructure evolution, property
relationship will be established for industrial applications.
 The processing maps will be generated for application in semi solid (liquid
metal processing) rolling.

64. DEVELOPMENT OF MULTIPHASE STEELS FOR AUTOMOTIVE
APPLICATIONS
C Si Mn P S V N Cr Fe
0.38 0.68 1.5 0.022 0.06 0.11 0.066 0.18 Balance
Chemical Composition 38MnSiVS5 (Wt. %)

65. Parameters FP FBM TM
Micro Hardness
(HV)
P: 290-301
F: 240-265
F:270-285
B/M:325-345
330-347
0.2% Yield
Strength (MPa)
721 1284 1185
Referene :Dr.V.Sivaraman et.al.
Steel billet supplied by TATA Steel (Ferrite & Pearlite )

66. THANK YOU