Title of Invention	AN INSITU METHOD OF NONDESTRUCTIVE ULTRASONIC MEASUREMENT OF R-BAR ON CORELATING DEVICE FEATURES WITH TIME OF FLIGHTS OF ULTRASONIC WAVE IN STEEL SHEETS .
Abstract	The invention relates to an in-situ method of non-destructive ultrasonic measurement of formability (r-bar) in cold-rolled and annealed steel sheets, comprising the steps of providing at least two surface wave probes fixed on a perspex sheet at a fixed distance; providing a digital ultrasonic flaw detector, and a computer-controlled pulse receiver; measuring ultrasonic time of flights at different rolling directions between the probes using the flaw detector and the pulse receiver; establishing a device feature relationship including a composition relationship; correlating the measured time flights with the device feature relationship including the composition relationship; and measuring the r-bar based on the correlated measured time flights, wherein, r-bar= ([0.160761A + 0.221348B + 0.222373C- 0.61272D-3.15983E + 0.946728F + 28.3329G-6.01249H + 1.0484011- 0.04484J] + K), and wherein, A = T0, B= T45, C= T90, D= Tbar, E= % C, F= % Mn, G= % P, H= % Ti, 1= % Al, J= Hardness value in HRB, K= 3.55564 , time of flight measured in micro u- sec, chemical composition is in weight %, the correlation co-efficient R-square is 0.9947.

Title of Invention

AN INSITU METHOD OF NONDESTRUCTIVE ULTRASONIC MEASUREMENT OF R-BAR ON CORELATING DEVICE FEATURES WITH TIME OF FLIGHTS OF ULTRASONIC WAVE IN STEEL SHEETS .

Abstract

The invention relates to an in-situ method of non-destructive ultrasonic measurement of formability (r-bar) in cold-rolled and annealed steel sheets, comprising the steps of providing at least two surface wave probes fixed on a perspex sheet at a fixed distance; providing a digital ultrasonic flaw detector, and a computer-controlled pulse receiver; measuring ultrasonic time of flights at different rolling directions between the probes using the flaw detector and the pulse receiver; establishing a device feature relationship including a composition relationship; correlating the measured time flights with the device feature relationship including the composition relationship; and measuring the r-bar based on the correlated measured time flights, wherein, r-bar= ([0.160761*A + 0.221348*B + 0.222373*C- 0.61272*D-3.15983*E + 0.946728*F + 28.3329*G-6.01249*H + 1.048401*1- 0.04484*J] + K), and wherein, A = T0, B= T45, C= T90, D= Tbar, E= % C, F= % Mn, G= % P, H= % Ti, 1= % Al, J= Hardness value in HRB, K= 3.55564 , time of flight measured in micro u- sec, chemical composition is in weight %, the correlation co-efficient R-square is 0.9947.

Full Text	FIELD OF INVENTION The present invention relates to a method for non-destructive measurement of ultrasonic time of flight for a fixed distance in rolling direction for example 45 and 90 degree to the rolling direction. The invention further relates to a method of predicting formability r bar in cold rolled and annealed steel sheets by correlating these ultrasonic parameters, sample thickness and composition of the grades of steel sheets. More particularly, the invention relates to an in-situ method of non-destructive ultrasonic measurement including co-relation of device features to accurately and quickly determine r-bar in cold rolled and annealed steel sheets. BACKGROUND OF THE INVENTION The cold rolled and annealed steel sheets develop directionally (anisotropy) which shows change in mechanical properties like elastic modules, yield strength, ductility in different directions. Generally minimum and maximum values of these quantities occur at 0°, and around at vicinity of 45° and 90° with respect to the rolling direction. When forming a sheet metal, practical consequences of directionality, a measure of formability, include phenomena for example, excess wrinkling, puckering ear forming, local thinning or rupture, which might lead to scrapturing of the steel sheets. A more serious consequence may be the downtime required to correct the manufacturing process. The severity of directionality (a measure of formability) in conventional method is measured as plastic strain ratio defined as where ew is the strain ratio in the width direction and et is that in the thickness direction. The normal anisotropy is defined as The phenomenon 'anisotrophy' or r bar has been found to be a parameter to control the drawability and hence formality of the steel sheets. Usually it is measured by destructive methods of testing in which the samples need to be cut from the sheets. These methods include tensile testing and magnetostrictive oscillator technique to determine resonance frequency in a specified specimen length. r bar values can also be determined by other technique like XRD (X-ray diffraction) which is again destructive, include localized measurements, time taking and tedious. JP 57008444 (A) discloses a method to perform on-line decision of the material characteristics of a steel plate and its anisotropy during traveling by measuring the rate of propagation of elastic wave in the steel plate. Accordingly, a Y-cut crystal oscillator is used as a transverse wave transmitter. A radio receiving terminal 1 and a transmitting terminal 2 are made in one place and are so set that both are located always at a constant distance. The center C of a bar connecting both is aligned roughly to the center of the plate width on the traveling line of a steel plate P and the bar is made rotatable around the central axis C. Water nozzles 3, 4 are provided in order to acoustically couple a transmitter and a surface to be inspected as well as a receiver and the surface to be inspected. The terminals 1,2 are turned around the normal axis of the steel plate to measure the rates of propagation in the plural directions within the surface. Usually, the values in the three directions: a rolling direction, a 45 deg direction and a 90 deg. direction, are measured at constant periods of intermittently. The average rates of propagation of the steel plate or the average modulus of rigidity of the steel plate is calculated from the measured values of the rates of propagation in the respective directions; at the same time, the in- surface anisotropy of the material characteristics of the steel plate is evaluated from the modulus G of rigidity in the respective directions. Thus there exists a need for a method for non-destructive ultrasonic measurements to quickly determine r bar which provides larger volume for ultrasonic waves to interact with the different crystallographic planes which incorporate the directionality (a measure of formability) in the steel sheets. OBJECTS OF THE INVENTION Accordingly, it is an object of the present invention to propose an in-situ method of non-destructive ultrasonic measurement including co-relation of device features to accurately and quickly determine r-bar in cold rolled and annealed steel sheets which is non-destructive and does not need to cut the sheets to prepare samples for testing. Another object of the invention is to propose an in-situ method of non- destructive ultrasonic measurement including co-relation of device features to accurately and quickly determine r-bar in cold rolled and annealed steel sheets which allows larger volume of ultrasonic waves to interact with different crystallographic planes which incorporate the directionality in the steel sheets. A further object of the invention is to propose an in-situ method of non- destructive ultrasonic measurement including co-relation of device features to accurately and quickly determine r-bar in cold rolled and annealed steel sheets which can be carried-out on the shop floor itself. A still further object of the invention is to propose an in-situ method of non- destructive ultrasonic measurement including co-relation of device features to accurately and quickly determine r-bar in cold rolled and annealed steel sheets which adapts digital ultrasonic flow director and direct contact process using two probes. Yet another object of the invention is to propose an in-situ method of non- destructive ultrasonic measurement including co-relation of device features to accurately and quickly determine r-bar in cold rolled and annealed steel sheets which is capable to being performed online by mere use of additional instruction. SUMMARY OF THE INVENTION Experimental results have proved that using two surface waves probes of frequency 4MHz (one transmitter and another receiver fixed in a Perspex sheet at a fixed distance) and measuring the time of flight of ultrasonic waves from transmitter to receiver, it is possible to determine the formability r bar in cold rolled and annealed sheets within an accuracy of ± 1.69%. For this, a device feature relationship for correlating the time of flights in rolling direction (To) as well as those at 45 and 90 degrees with respect to rolling direction (T45) and (T90) respectively, including %C, %Mn, %P, % MA (microalloying elements), % AI hardness in HRB and the formability r bar, has been established. The device feature relationship leading to measurement of r bar according to the invention is : r bar= (0.160761 * A + 0.221348B + 0.2223730 0.61272D-3.15983E + 0.946728F+28.3329G - 6.01249H + 1.0484011 - 0.04484J+K) where, A = To B=T45 C= T90 D= Tbar E= % C F= % Mn G= % P H= % Ti 1= % A1 J= Hardness value, HRB K= 3.55564 The time of flight are measured in micro u sec. The chemical composition is in weight %. The correlation co-efficient r square is found to be 0.9947. Accordingly, there is provided an in-situ method of non-destructive ultrasonic measurement including correlating of device features to accurately and quickly determine r-bar in cold rolled and annealed steel sheets, comprising providing a digital ultrasonic flaw detector, and a computer controlled pulse receiver; providing atleast two probes fixed in a perspex sheet at a fixed distance; measuring ultrasonic time of flights using the atleast two probes and the flaw detector in the directions 0°, 45° and 90° with respect to rolling direction in different steel sheets; correlating the measured time of flights with the device features of the steel sheets including the formability r bar to establish a device feature relationship such as: BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Figure 1 - a pictorial view showing measurement of Time of Flight of ultrasonic wave from transmitter to receiver at 45 to the rolling direction. Figure 2 - a pictorial view showing a typical RF signal for measurement of Time of Flight of ultrasonic wave between transmitter to receiver. Figure 3 - a schematic diagram showing angles from the rolling direction along which time of flight was measured from the RF signals. Figure 4 - a graphical representation showing correlation between measured r bar using module r bar tester and ultrasonically predicted r bar in CQ, DQ, EDD and IF grades of cold rolled and annealed steel sheets. Figure 5 - a graphical representation showing error in ultrasonically r bar values. Figure 6 - shows a graphical representation of the linear line fit graph between T0 and predicted r bar which although shows a poor correlation but the trend indicates decrease in r bar with increase in T0. Figure 7 - shows a linear line fit graph between T45 and predicted r bar which shows a good correlation and the trend indicates decrease in r bar with increase in T45. Figure 8 - shows a linear line fit graph between Tbat and predicted r bar which shows a poor correlation but the trend indicates decrease in r bar with increase in T90. Figure 9 - shows a linear line fit graph between Tbar and predicted r bar which shows a fair correlation and the trend indicates decrease in r bar with increase in Tbar. Figure 10 - shows a linear line fit graph between % C and predicted r bar which shows a good correlation and the trend indicates decrease in r bar with increase in % C. Figure 11 - shows a linear line fit graph between % Mn and predicted r bar which shows a good correlation and the trend indicates decrease in r bar with increase in % Mn. Figure 12 - shows a linear line fit graph between % P and predicted r bar which shows a poor correlation but the trend indicates decrease in r bar with increase in % Mn. Figure 13 - shows a linear line fit graph between % 71 and predicted r bar which shows a fair correlation but the trend indicates increase in r bar with increase in % Mn. Figure 14 - shows a linear line fit graph between % Al and predicted r bar which shows a poor correlation but the trend indicates decrease in r bar with increase in % Mn. Figure 15 - shows a linear line fit graph between hardness and predicted r bar which shows a good correlation and the trend indicate decrease in r bar with increase in hardness HRB. DETAILED DESCRIPTION OF THE INVENTION As shown in the accompanying Figures constituting graphical and schematic diagrams.. The surface wave of ultrasound generally travel along the surface of a material at a depth of one wavelength from the surface. While traveling, it interacts with the detailed structure of the medium in which it travels. In cold rolled and annealed steel sheets the wave velocity changes in different directions from the rolling direction depending upon the intensity of different cryatallographic planes, which govern directionality (a measure of formability) in the steel sheets. As time of flight is directly related to the ultrasonic velocity its value in 0, 45 and 90 degree from the rolling direction along with the chemistry like % C, % Mn, % P, % MA (micro-alloying elements), % Al and hardness in HRB can be correlated with the r bar. It has been observed from the correlation that decreasing % C, % Mn, % P and thickness of the test sample increases r bar value and hence the formability of the steel sheets. Increase in microalloying elements increase r bar value and decrease in Tbar which indicates an increase in r bar. Such device feature relationship can be used for non-destructive prediction of r bar in cold rolled and annealed steel on the shop floor. EXPERIMENTAL WORK Details of the materials used for ultrasonic evaluation : CQ, DQ, EDD, IF grades of steel produced by TATA STEEL Details of the Digital Ultrasonic Equipment & Surface Wave Probe : Make 7 Model : Ultrasonic Flaw detector EPOCH-4, and computer controlled Pulser Receiver PR-5800, Panametrics, USA. Probe : 4MHz, 8x9 mm, 90° angle (Surface wave) Technique : Through transmission using two probes fixed in a Perspex sheet at a fixed distance as shown in Fig. 1. Time of flight was measured from the RF signals by as shown in Fig. 2. Couplant: Machine oil The details of the samples considered for ultrasonic measurements have been shown in Table 1 and Table 2. r bar was measurement by Magnetostrictive Oscillator Technique in the directions as shown in Fig. 3. Ultrasonic time of flights in the directions 0°, 45° and 90° from the rolling direction in different sheets were measured in CQ, DQ, EDD, IF grades of steel sheets. These were tested for r bar measurement using Magnetostrictive Oscillator Technique and the results tabulated in Table 3. A correlation has been obtained to predict r bar as shown in equation (1) and Fig. 4. A good correlation has been obtained between the measured r bar ad ultrasonically predicted r bar. We Claim: 1. An in-situ method of non-destructive ultrasonic measurement of formability (r-bar) in cold-rolled and annealed steel sheets, comprising the steps of: -providing at least two surface wave probes fixed on a perspex sheet at a fixed distance; -providing a digital ultrasonic flaw detector, and a computer-controlled pulse receiver; -measuring ultrasonic time of flights at different rolling directions between the probes using the flaw detector and the pulse receiver; -establishing a device feature relationship including a composition relationship; -correlating the measured time flights with the device feature relationship including the composition relationship; and -measuring the r-bar based on the correlated measured time flights, wherein, r-bar= ([0.160761A + 0.221348B + 0.222373C- 0.61272D-3.15983E + 0.946728F + 28.3329G-6.01249H + 1.0484011- 0.04484J] + K), and wherein, A = T0, B= T45, C= T90, D= Tbar, E= % C, F= % Mn, G= % P, H= % Ti, 1= % Al, J= Hardness value in HRB, K= 3.55564 , time of flight measured in micro u- sec, chemical composition is in weight %, the correlation co-efficient R-square is 0.9947. 2. The method as claimed in claim 1, wherein the device features further comprises composition of the material constituting the steel sheets including its hardness. 3. The method as claimed in claim 1, wherein magnetostrictive oscillator technique is used in measurement of the r-bar. 4. The method as claimed in claim 1, wherein the atleast two probes comprises one each transmitter and receiver. 5. An in-situ method of non-destructive ultrasonic measurement of formability (r- bar) in cold-rolled and annealed steel sheets, as substantially described herein with reference to the accompanying drawings. The invention relates to an in-situ method of non-destructive ultrasonic measurement of formability (r-bar) in cold-rolled and annealed steel sheets, comprising the steps of providing at least two surface wave probes fixed on a perspex sheet at a fixed distance; providing a digital ultrasonic flaw detector, and a computer-controlled pulse receiver; measuring ultrasonic time of flights at different rolling directions between the probes using the flaw detector and the pulse receiver; establishing a device feature relationship including a composition relationship; correlating the measured time flights with the device feature relationship including the composition relationship; and measuring the r-bar based on the correlated measured time flights, wherein, r-bar= ([0.160761A + 0.221348B + 0.222373C- 0.61272D-3.15983E + 0.946728F + 28.3329G-6.01249H + 1.0484011- 0.04484J] + K), and wherein, A = T0, B= T45, C= T90, D= Tbar, E= % C, F= % Mn, G= % P, H= % Ti, 1= % Al, J= Hardness value in HRB, K= 3.55564 , time of flight measured in micro u- sec, chemical composition is in weight %, the correlation co-efficient R-square is 0.9947.

Full Text

FIELD OF INVENTION
The present invention relates to a method for non-destructive measurement of
ultrasonic time of flight for a fixed distance in rolling direction for example 45
and 90 degree to the rolling direction. The invention further relates to a method
of predicting formability r bar in cold rolled and annealed steel sheets by
correlating these ultrasonic parameters, sample thickness and composition of the
grades of steel sheets. More particularly, the invention relates to an in-situ
method of non-destructive ultrasonic measurement including co-relation of
device features to accurately and quickly determine r-bar in cold rolled and
annealed steel sheets.
BACKGROUND OF THE INVENTION
The cold rolled and annealed steel sheets develop directionally (anisotropy)
which shows change in mechanical properties like elastic modules, yield strength,
ductility in different directions. Generally minimum and maximum values of these
quantities occur at 0°, and around at vicinity of 45° and 90° with respect to the
rolling direction. When forming a sheet metal, practical consequences of
directionality, a measure of formability, include phenomena for example, excess
wrinkling, puckering ear forming, local thinning or rupture, which might lead to
scrapturing of the steel sheets. A more serious consequence may be the
downtime required to correct the manufacturing process.
The severity of directionality (a measure of formability) in conventional method is
measured as plastic strain ratio defined as

where ew is the strain ratio in the width direction and et is that in the thickness
direction.

The normal anisotropy is defined as

The phenomenon 'anisotrophy' or r bar has been found to be a parameter to
control the drawability and hence formality of the steel sheets. Usually it is
measured by destructive methods of testing in which the samples need to be cut
from the sheets. These methods include tensile testing and magnetostrictive
oscillator technique to determine resonance frequency in a specified specimen
length. r bar values can also be determined by other technique like XRD (X-ray
diffraction) which is again destructive, include localized measurements, time
taking and tedious.
JP 57008444 (A) discloses a method to perform on-line decision of the material
characteristics of a steel plate and its anisotropy during traveling by measuring
the rate of propagation of elastic wave in the steel plate. Accordingly, a Y-cut
crystal oscillator is used as a transverse wave transmitter. A radio receiving
terminal 1 and a transmitting terminal 2 are made in one place and are so set
that both are located always at a constant distance. The center C of a bar
connecting both is aligned roughly to the center of the plate width on the
traveling line of a steel plate P and the bar is made rotatable around the central
axis C. Water nozzles 3, 4 are provided in order to acoustically couple a
transmitter and a surface to be inspected as well as a receiver and the surface to
be inspected. The terminals 1,2 are turned around the normal axis of the steel
plate to measure the rates of propagation in the plural directions within the
surface. Usually, the values in the three directions: a rolling direction, a 45 deg
direction and a 90 deg. direction, are measured at constant periods of

intermittently. The average rates of propagation of the steel plate or the average
modulus of rigidity of the steel plate is calculated from the measured values of
the rates of propagation in the respective directions; at the same time, the in-
surface anisotropy of the material characteristics of the steel plate is evaluated
from the modulus G of rigidity in the respective directions.
Thus there exists a need for a method for non-destructive ultrasonic
measurements to quickly determine r bar which provides larger volume for
ultrasonic waves to interact with the different crystallographic planes which
incorporate the directionality (a measure of formability) in the steel sheets.
OBJECTS OF THE INVENTION
Accordingly, it is an object of the present invention to propose an in-situ method
of non-destructive ultrasonic measurement including co-relation of device
features to accurately and quickly determine r-bar in cold rolled and annealed
steel sheets which is non-destructive and does not need to cut the sheets to
prepare samples for testing.
Another object of the invention is to propose an in-situ method of non-
destructive ultrasonic measurement including co-relation of device features to
accurately and quickly determine r-bar in cold rolled and annealed steel sheets
which allows larger volume of ultrasonic waves to interact with different
crystallographic planes which incorporate the directionality in the steel sheets.

A further object of the invention is to propose an in-situ method of non-
destructive ultrasonic measurement including co-relation of device features to
accurately and quickly determine r-bar in cold rolled and annealed steel sheets
which can be carried-out on the shop floor itself.
A still further object of the invention is to propose an in-situ method of non-
destructive ultrasonic measurement including co-relation of device features to
accurately and quickly determine r-bar in cold rolled and annealed steel sheets
which adapts digital ultrasonic flow director and direct contact process using two
probes.
Yet another object of the invention is to propose an in-situ method of non-
destructive ultrasonic measurement including co-relation of device features to
accurately and quickly determine r-bar in cold rolled and annealed steel sheets
which is capable to being performed online by mere use of additional instruction.
SUMMARY OF THE INVENTION
Experimental results have proved that using two surface waves probes of
frequency 4MHz (one transmitter and another receiver fixed in a Perspex sheet
at a fixed distance) and measuring the time of flight of ultrasonic waves from
transmitter to receiver, it is possible to determine the formability r bar in cold
rolled and annealed sheets within an accuracy of ± 1.69%. For this, a device
feature relationship for correlating the time of flights in rolling direction (To) as
well as those at 45 and 90 degrees with respect to rolling direction (T45) and
(T90) respectively, including %C, %Mn, %P, % MA (microalloying elements), %
AI hardness in HRB and the formability r bar, has been established. The device
feature relationship leading to measurement of r bar according to the invention is
: r bar= (0.160761 * A + 0.221348*B + 0.222373*0 0.61272*D-3.15983E +
0.946728*F+28.3329*G - 6.01249*H + 1.048401*1 - 0.04484*J+K)

where,
A = To
B=T45
C= T90
D= Tbar
E= % C
F= % Mn
G= % P
H= % Ti
1= % A1
J= Hardness value, HRB
K= 3.55564

The time of flight are measured in micro u sec. The chemical composition is in
weight %. The correlation co-efficient r square is found to be 0.9947.
Accordingly, there is provided an in-situ method of non-destructive ultrasonic
measurement including correlating of device features to accurately and quickly
determine r-bar in cold rolled and annealed steel sheets, comprising providing a
digital ultrasonic flaw detector, and a computer controlled pulse receiver;
providing atleast two probes fixed in a perspex sheet at a fixed distance;
measuring ultrasonic time of flights using the atleast two probes and the flaw
detector in the directions 0°, 45° and 90° with respect to rolling direction in
different steel sheets; correlating the measured time of flights with the device
features of the steel sheets including the formability r bar to establish a device
feature relationship such as:

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 - a pictorial view showing measurement of Time of Flight of ultrasonic wave
from transmitter to receiver at 45 to the rolling direction.
Figure 2 - a pictorial view showing a typical RF signal for measurement of Time of Flight
of ultrasonic wave between transmitter to receiver.
Figure 3 - a schematic diagram showing angles from the rolling direction along which
time of flight was measured from the RF signals.
Figure 4 - a graphical representation showing correlation between measured r bar using
module r bar tester and ultrasonically predicted r bar in CQ, DQ, EDD and IF grades of
cold rolled and annealed steel sheets.
Figure 5 - a graphical representation showing error in ultrasonically r bar values.
Figure 6 - shows a graphical representation of the linear line fit graph between T0 and
predicted r bar which although shows a poor correlation but the trend indicates decrease
in r bar with increase in T0.
Figure 7 - shows a linear line fit graph between T45 and predicted r bar which shows a
good correlation and the trend indicates decrease in r bar with increase in T45.

Figure 8 - shows a linear line fit graph between Tbat and predicted r bar which shows a
poor correlation but the trend indicates decrease in r bar with increase in T90.
Figure 9 - shows a linear line fit graph between Tbar and predicted r bar which shows a
fair correlation and the trend indicates decrease in r bar with increase in Tbar.
Figure 10 - shows a linear line fit graph between % C and predicted r bar which shows
a good correlation and the trend indicates decrease in r bar with increase in % C.
Figure 11 - shows a linear line fit graph between % Mn and predicted r bar which shows
a good correlation and the trend indicates decrease in r bar with increase in % Mn.
Figure 12 - shows a linear line fit graph between % P and predicted r bar which shows
a poor correlation but the trend indicates decrease in r bar with increase in % Mn.
Figure 13 - shows a linear line fit graph between % 71 and predicted r bar which shows
a fair correlation but the trend indicates increase in r bar with increase in % Mn.
Figure 14 - shows a linear line fit graph between % Al and predicted r bar which shows
a poor correlation but the trend indicates decrease in r bar with increase in % Mn.

Figure 15 - shows a linear line fit graph between hardness and predicted r bar which
shows a good correlation and the trend indicate decrease in r bar with increase in
hardness HRB.
DETAILED DESCRIPTION OF THE INVENTION
As shown in the accompanying Figures constituting graphical and schematic diagrams..
The surface wave of ultrasound generally travel along the surface of a material at a
depth of one wavelength from the surface. While traveling, it interacts with the detailed
structure of the medium in which it travels. In cold rolled and annealed steel sheets the
wave velocity changes in different directions from the rolling direction depending upon
the intensity of different cryatallographic planes, which govern directionality (a measure
of formability) in the steel sheets.
As time of flight is directly related to the ultrasonic velocity its value in 0, 45 and 90
degree from the rolling direction along with the chemistry like % C, % Mn, % P, % MA
(micro-alloying elements), % Al and hardness in HRB can be correlated with the r bar.
It has been observed from the correlation that decreasing % C, % Mn, % P and
thickness of the test sample increases r bar value and hence the formability of the steel
sheets. Increase in microalloying elements increase r bar value and decrease in Tbar
which indicates an increase in r bar.
Such device feature relationship can be used for non-destructive prediction of r bar in
cold rolled and annealed steel on the shop floor.

EXPERIMENTAL WORK
Details of the materials used for ultrasonic evaluation :
CQ, DQ, EDD, IF grades of steel produced by TATA STEEL
Details of the Digital Ultrasonic Equipment & Surface Wave Probe :
Make 7 Model : Ultrasonic Flaw detector EPOCH-4, and computer controlled
Pulser Receiver PR-5800, Panametrics, USA.
Probe : 4MHz, 8x9 mm, 90° angle (Surface wave)
Technique : Through transmission using two probes fixed in a Perspex sheet at a
fixed distance as shown in Fig. 1. Time of flight was measured from the RF
signals by as shown in Fig. 2.
Couplant: Machine oil
The details of the samples considered for ultrasonic measurements have been
shown in Table 1 and Table 2. r bar was measurement by Magnetostrictive
Oscillator Technique in the directions as shown in Fig. 3. Ultrasonic time of flights
in the directions 0°, 45° and 90° from the rolling direction in different sheets
were measured in CQ, DQ, EDD, IF grades of steel sheets. These were tested for
r bar measurement using Magnetostrictive Oscillator Technique and the results
tabulated in Table 3.

A correlation has been obtained to predict r bar as shown in equation (1) and
Fig. 4. A good correlation has been obtained between the measured r bar ad
ultrasonically predicted r bar.

We Claim:
1. An in-situ method of non-destructive ultrasonic measurement of
formability (r-bar) in cold-rolled and annealed steel sheets, comprising the
steps of:
-providing at least two surface wave probes fixed on a perspex sheet
at a fixed distance;
-providing a digital ultrasonic flaw detector, and a computer-controlled
pulse receiver;
-measuring ultrasonic time of flights at different rolling directions
between the probes using the flaw detector and the pulse receiver;
-establishing a device feature relationship including a composition
relationship;
-correlating the measured time flights with the device feature
relationship including the composition relationship; and
-measuring the r-bar based on the correlated measured time flights,
wherein,

r-bar= ([0.160761*A + 0.221348*B + 0.222373*C- 0.61272*D-3.15983*E +
0.946728*F + 28.3329*G-6.01249*H + 1.048401*1- 0.04484*J] + K), and
wherein,

A = T0, B= T45, C= T90, D= Tbar, E= % C, F= % Mn, G= % P, H= % Ti, 1= %
Al, J= Hardness value in HRB, K= 3.55564 , time of flight measured in micro u-
sec, chemical composition is in weight %, the correlation co-efficient R-square is
0.9947.
2. The method as claimed in claim 1, wherein the device features further
comprises composition of the material constituting the steel sheets including its
hardness.
3. The method as claimed in claim 1, wherein magnetostrictive oscillator
technique is used in measurement of the r-bar.
4. The method as claimed in claim 1, wherein the atleast two probes comprises
one each transmitter and receiver.

5. An in-situ method of non-destructive ultrasonic measurement of formability (r-
bar) in cold-rolled and annealed steel sheets, as substantially described herein
with reference to the accompanying drawings.

The invention relates to an in-situ method of non-destructive ultrasonic
measurement of formability (r-bar) in cold-rolled and annealed steel sheets,
comprising the steps of providing at least two surface wave probes fixed on a
perspex sheet at a fixed distance; providing a digital ultrasonic flaw detector, and
a computer-controlled pulse receiver; measuring ultrasonic time of flights at
different rolling directions between the probes using the flaw detector and the
pulse receiver; establishing a device feature relationship including a composition
relationship; correlating the measured time flights with the device feature
relationship including the composition relationship; and measuring the r-bar
based on the correlated measured time flights, wherein,
r-bar= ([0.160761*A + 0.221348*B + 0.222373*C- 0.61272*D-3.15983*E +
0.946728*F + 28.3329*G-6.01249*H + 1.048401*1- 0.04484*J] + K), and
wherein,

A = T0, B= T45, C= T90, D= Tbar, E= % C, F= % Mn, G= % P, H= % Ti, 1= %
Al, J= Hardness value in HRB, K= 3.55564 , time of flight measured in micro u-
sec, chemical composition is in weight %, the correlation co-efficient R-square is
0.9947.

Documents:

281-KOL-2006-(12-12-2011)-FORM-27.pdf

281-kol-2006-granted-abstract.pdf

281-kol-2006-granted-claims.pdf

281-kol-2006-granted-correspondence.pdf

281-kol-2006-granted-description (complete).pdf

281-kol-2006-granted-drawings.pdf

281-kol-2006-granted-examination report.pdf

281-kol-2006-granted-form 1.pdf

281-kol-2006-granted-form 18.pdf

281-kol-2006-granted-form 2.pdf

281-kol-2006-granted-form 3.pdf

281-kol-2006-granted-gpa.pdf

281-kol-2006-granted-reply to examination report.pdf

281-kol-2006-granted-specification.pdf

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Patent Number

228094

Indian Patent Application Number

281/KOL/2006

PG Journal Number

05/2009

Publication Date

30-Jan-2009

Grant Date

28-Jan-2009

Date of Filing

29-Mar-2006

Name of Patentee

TATA STEEL LIMITED

Applicant Address

JAMSHEDPUR-831 001

Inventors:

#	Inventor's Name	Inventor's Address
1	J.C. PANDEY	TATA STEEL LIMITED JAMSHEDPUR-831 001
2	DR. MANISH RAJ	TATA STEEL LIMITED JAMSHEDPUR-831 001

PCT International Classification Number

G01N 29/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA