DESC:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patent Rules, 2003
COMPLETE SPECIFICATION
(See sections 10 & rule 13)
1. TITLE OF THE INVENTION
A DULL FINISH COMPOSITION AND ITS METHOD OF PREPARATION
2. APPLICANT (S)
NAME NATIONALITY ADDRESS
BEML LIMITED IN BEML Soudha, No 23/1, 4th Main S.R. Nagar, Bengaluru- 560027, Karnataka, India.
3. PREAMBLE TO THE DESCRIPTION
COMPLETE SPECIFICATION

The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF INVENTION:
[001] The present invention relates to the field of development of special dull finish obtained through rolling route on stainless steels sheets & coils. The present invention in particular relates to a dull finish with dead light temper (DLT) on the exteriors/ side wall of the coaches and its method of production by rolling route.
DESCRIPTION OF THE RELATED ART:
[002] Cities play a vital role in promoting economic growth and prosperity of the Nation. The development of the cities largely depends upon their physical, social and institutional infrastructure. The intra-urban transportation acts as a catalyst in the cities’ development.
[003] The urban transport situation in most of the cities in India is deteriorating. The deterioration is more prevalent in Metropolitan cities where there is an excessive concentration of road transportation vehicles which is leading to acute road congestion, rising air pollution and a high level of accident risk. There is a growing realization that rail based urban transport can play a major role in alleviating these ills to a large extent. The rail based transport services are available only in a few mega cities like Mumbai, Delhi, Kolkata and Chennai. Most of these cities use wide body Electric Multiple Units (EMUs) for their urban transport. Even these EMUs are of old design and the car bodies are made up of carbon steel. As most of these cities are situated in coastal regions, the life of these EMUs are short as the carbon steel bodies are prone to corrosion.
[004] Reference may be made to the following:
[005] IN Publication No. 699/CHE/2009 relates to design of complete carbody of the EMU comprising modules except the body bolster with austenitic stainless steel sheets to grade SUS 301L in different cold rolled tempers and ferritic stainless steel to grade AlSl 409M. The body bolster is made of low alloy high tensile (LAHT) structural steel. The width of the carbody is designed to be extrawide and is 3660 mm. The structural design of the carbody is based on the specified super dense crush load (SDCL) of 16 persons per square meter and the mechanical strength of the car body structural design complies with the requirements of UIC 566. This is for car body design using different grades OI stainless steels. No specific surface finish is mentioned.
[006] IN Publication No. 202041049383 relates to a system and method for development of special 2j finish on steel sheets/ coils for rolling stocks. The finish is achieved on the stainless steel sheets by special rolling and strip grinding line process. In strip grinding line process the sheets are processed through different grits of belts to achieve desired finish.
[007] IN Publication No. 202117032947 relates to clear-coated stainless steel sheet comprises: a stainless steel sheet; and a clear coating film that is formed on at least one surface of the stainless steel sheet, while having an average film thickness of from 0.05 µm to 3.00 µm.
[008] Publication No. PH12016501749 relates to a stainless steel sheet that can be easily cleaned and has good anti-glare characteristics. The stainless steel sheet is manufactured through a temper rolling process using a dull roll after a finish cold rolling process and a bright annealing process. The stainless steel sheet has an arithmetic average surface roughness Ra of 0.2 to 1.2 mm in a direction perpendicular to a rolling direction. In addition, the stainless steel sheet has a transfer ratio of 15 to 70 pcnt which is an area ratio of a portion to which a dull shape is transferred and the surface of the stainless steel sheet. Furthermore, the density of micro pits formed in the surface of the steel sheet and having a depth of 0.5 mm or more and an area of 10 mm2 or more is 10.0/0.01 mm2 or less, and the area ratio of the micro pits to the surface of the steel sheet is 1.0 pcnt or less.
[009] Publication No. JP2016196682 relates to an austenitic stainless steel sheet excellent in washability, antiglare properties and hydrophilic properties. In an austenitic stainless steel sheet obtained by performing skinpass rolling using a dull roll after finish cold rolling and bright rolling, the arithmetic average roughness Ra in a direction vertical to the rolling direction in the surface of the steel sheet is 0.2 to 1.2 µm. Further, the transfer ratio of a dull pattern in the surface of the steel sheet is 15 to 70%. Further, in micropits formed in the surface of the steel sheet, and having a depth of 0.5 µm or higher and an opening area of 10 µm, existence density is 10.0 pieces or lower per 0.01 mm, and also, opening part area ratio is 1.0% or lower. Further, the film formed on the surface of the steel sheet is composed of oxide essentially consisting of SiO including, as film forming elements other than C, at least Si, N, Al, Mn, Cr, Fe, Nb, Ti and O, and also having an Si content of 10 atomic% or higher and an N content of 10 atomic% or lower.
[010] Publication No. KR20010065236 relates to a method for manufacturing a dull finish stainless steel sheet is provided to directly manufacture a dull finish stainless steel sheet having excellent surface roughness and flatness without additional processes by skin-passing the stainless steel sheet after directly adhering a medium for dull finish treatment to a strip to be rolled when skin-passing a first cold rolled stainless steel sheet without using a dull finish rolling roll. The method for manufacturing a dull finish stainless steel sheet comprises the steps of manufacturing steel sheet by melting, refining, casting and hot rolling a stainless steel raw material; hot annealing step of annealing and softening the manufactured steel sheet; pickling treatment step of hot pickling the annealed steel sheet; manufacturing the steel sheet into a thin steel sheet by cold rolling the pickling treated steel sheet; cold annealing and pickling or bright annealing the cold rolled thin steel sheet; and forming dull finish patterns on one surface or both surfaces of the skin-passed thin steel sheet by skin-passing the annealed thin steel sheet together with a composite film on which dull finish patterns are formed.
[011] Publication No. JP2002346608 relates to a rolling method to produce a stainless steel plate with antiglareness and dull-finish of uniform colour tone. When a stainless steel plate is rolled in a cold status, a pair of work rolls after having a dull processing are built in a rolling mill and revolve more than 100 times while both work rolls being kept in direct contact each other so as to let work rolls have an initial wearout compulsorily. Then, the inside of this rolling mill is cleaned to remove an abrasion powder and the cold rolling is performed for the stainless steel plate by using a pair of work rolls after an initial abrasion.
[012] Publication No. JP2002346607 relates to a rolling method which produces a stainless steel plate with antiglareness and dull-finish of uniform colour tone. When a stainless steel plate is rolled in a cold status, a pair of work rolls after having a dull processing are built in a rolling mill and a break-in rolling is performed for a distance of more than 100 times as long as a circumferential length of this work roll to let a pair of work rolls have an initial wearout compulsorily. Then, the inside of this rolling mill is cleaned to remove an abrasion powder and the cold rolling is performed for the stainless steel plate by using a pair of work rolls after having an initial wearout to produce a dull-finished stainless steel plate.
[013] Publication No. JPH09122579 relates to increase coating film adhesion by improving the prim coating and to provide a resin-coated stainless steel sheet excellent in surface property, adhesion, etc., without need for a dull skin pass. This resin-coated stainless steel sheet is obtained by forming a prim coating layer formed by incorporating 2-10wt.% hard silica powder into a coating film of an epoxy resin having 1500-3500 average mol.wt. an with the maximum roughness Rmax of the surface layer controlled to 2-4µm on the surface of a stainless steel coated with a chromated film at 5-50mg/m<2> total Cr and providing a finish coating layer on the prim coating layer.
[014] Publication No. JPH0987868 relates to reduce the dispersion of color tones among coils, in pickling treatment in which dull finish rolling is executed, by executing electrolytic treatment in which the concn. of sulfuric acid, temp. and electrolytic current density are regulated to specified values and thereafter executing electrolytic treatment in which the concn. of nitric acid, temp. and electrolytic current density are regulated to specified values. Solution: Pickling treatment after dull-finish rolling for a stainless steel sheet or at least one pickling treatment in annealing-pickling stages executed before and after the above is executed as the following manner. Electrolytic treatment is executed at 100 to 300mA/cm<2> electrolytic current density in an aq. soln. of sulfuric acid with 50 to 250g/L sulfuric acid concn. heated at 50 to 80'C. After that, electrolytic treatment is executed at 50 to 300mA/cm<2> electrolytic current density in an aq. soln. of nitric acid with 70 to 150g/L nitric acid concentration. heated at 50 to 80 deg.C. Since pickling is executed intensively compared to the conventional light pickling, the dispersion of micro surface ruggedness is reduced, and the color tones thereof are stabilized.
[015] Publication No. JPH0657913 relates to a dull-finish steel plate excellent in the appearance and having no visible spot by forming the plane shape of the recesses or protrusions uniformly distributed on the surface of a metallic plate to be almost circular form and making it so as not to change in the color tone in accordance with point of view. Recessions or protrusions 12 uniformly distributed on the surface of a stainless steel is formed to shape a circular plane. In this circle, a polygonal form having a number of sides is included. The size and the distribution rate of the recessions or protrusions 12 are decided in accordance with the uses. Even if a plurality of dull-finished steel plates are arranged in arbitrary directions to use for a roof or an external wall of a building, the surface is made invisible to be spotty. In this way, a dull-finish steel plate with a beautiful appearance can be obtained.
[016] Publication No. JPH079007 relates to a durable metal plate rarely showing stuck fingerprint by arranging approximately equal width rooves having a depth over the prescribed value many in parallel with having the center distance between adjacent grooves over the groove width in the prescribed range of width on surface. A groove is of equal width such that a groove width 1 of metal plate surface is in the range of 2mm-100mum and a groove depth 2 is of >=5mum. Also, when the center distance 3 between adjacent grooves is made over the groove width and many grooves are arranged in parallel, fingerprint is rarely show.
[017] Publication No. JPH0323309 relates to improve heat resisting fatigue property as well as to better brazing and adhesion of precious metal catalyst by setting the surface roughness of a metallic foil made of heat resisting steel used as exhaust gas catalyst support of automobile within a specific range. A catalyst support is constituted as a heat resisting stainless steel plane plate 1 and a wave plate 2 having specific thickness are multiplexically and cylindrically rolled in and they are inserted in a heat resisting stainless steel outer cylinder. The plane plate 1 and the wave plate 2 are reciprocally connected to each other with brazing, and a metallic foil made of heat resisting stainless steel having a honeycomb shape is formed. In the above constitution, the surface roughness of the metallic foil is set as 0.7 - 2.0mum. At the time of manufacture, a dull finish roll is used and cold rolling is carried out to obtain the dull finish metallic foil.
[018] Publication No. CN212263793 relates to a pre-coated steel plate applied to a stainless steel frosted material, which comprises a base plate main body, a frosted layer is arranged on the upper surface of the baseplate main body, a first chemical treatment layer is arranged on the upper surface of the frosted layer, finish paint is arranged on the upper surface of the first chemical treatment layer, and a second chemical treatment layer is arranged on the lower surface of the base plate. And back paint is arranged on the lower surface of the second chemical treatment layer. By the adoption of the technical scheme, the 430 stainless steel plate with the antirust function is adopted as the base plate body, patterns are manufactured on the upper surface of the base plate body through dull polish with diversified textures, the upper surface of the first chemical treatment layer is coated with the finishing coat through coating treatment of the first chemical treatment layer, the color effect can be effectively improved, and the service life of the base plate is prolonged. The protective property, the surface pollution resistance and the scratch resistance of the pattern are improved, the pattern loss can be effectively enhanced and avoided, and the service life of the pattern is prolonged.
[019] Publication No. WO0058024 relates to a coating composition includes a cured base coat of polyurethane-containing resin covered by a cured top coat of a silicon-containing resin. The top coat resin is applied in an uncured state to the base coat, the two resins are thereafter heated to at least 140 F, and thereafter the top coat resin is cured to produce the coating composition. A clean metal surface is coated with the coating composition by applying uncured base coat resin to the metal surface, curing the base coat resin, and thereafter applying the top coat as described above.
[020] Hence there was a need to develop a special dull finish on austenitic Stainless Steels, with specific properties for exterior car body applications with specified gloss reflectance & surface roughness. Also there needed an improved coating material which provided consistency in gloss values and surface roughness values.
[021] In order to overcome above listed prior art, the present invention aims to provide a special dull finish coating composition with dead light temper (DLT) on the exteriors/ side wall of the coaches and its method of preparation.
OBJECTS OF THE INVENTION:
[022] The principal object of the present invention is to provide a dull finish coating composition with dead light temper (DLT) on the exteriors/ side wall of the coaches and its method of preparation
[023] Another object of the present invention is to provide a composition providing a special finish with consistency in gloss values and surface roughness values.
SUMMARY OF THE INVENTION:
[024] The present invention relates to the dull finish parameters composition and method of preparing the dull finish composition for metro coaches. This is a dull finish coating composition with dead light temper (DLT) on the exteriors / side wall of the coaches and its method of preparation. The composition specification provides consistency in gloss values and surface roughness values. Also, this finish is developed on Austenitic Stainless Steels. DLT temper with specific gloss & surface roughness values, which will ensure consistency of finish during special rolling.
BREIF DESCRIPTION OF THE INVENTION
[025] It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments.
[026] Figure 1 shows developed dull finish according to the present invention;
[027] Figure 2 shows flowchart according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION:
[028] The present invention provides the dull finish parameters composition and method of preparing the dull finish composition for metro coaches. This is a dull finish coating composition with dead light temper (DLT) on the exteriors/ side wall of the coaches and its method of preparation. The composition specification provides consistency in gloss values and surface roughness values. Also, this finish is developed on Austenitic Stainless Steels. DLT temper with specific gloss & surface roughness values, which will ensure consistency of finish during special rolling.
[029] In the special ground rolls, steel coil is rolled to impart the required roughness and some dull property. Further the roughness & dullness is achieved through pickling cycles. The dead light temper (DLT) are achieved through cold rolling & annealing cycles.
[030] The method includes steel melting and hot rolling. Then annealing and pickling is done. Then the material is send to rolling mill for special rolling to impart dull finish roughness. Again annealing and pickling is done to obtain required dullness.
[031] The dull finish to be imparted on stainless steels as per the specifications to suit Metro car side wall applications, with specific values to maintain consistency of finish. The composition is given in table 1 and the Mechanical Properties are given in table 2.
Table 1:
Designation C Si Mn P S Ni Cr N Others
SUS 301L 0.030 max. 1.0 max. 2.0 max. 0.045 max. 0.030max. 6.0 ~ 8.0 16.0 ~ 18.0 0.20 max. -
Table 2
Stainless Steel Grade Proof Stress
(N/mm2) Tensile Strength
(N/mm2) Elongation (%),
(on 50mm GL) Bend test
Min. Max. Min. Max. Min. Bend angle Inside Radius
SUS 301L-DLT 345 485 690 860 40 180º ½ t
[032] Dull Finish:
[033] Surface condition having lower reflectivity by cold rolling with etched rollers and is applicable for the DLT grade. Glossiness (Gu) 35 ±5 (compared with 60-degree reflectivity standard sample) & surface roughness (Ra) in microns: 4.50 ± 0.5.
[034] For obtaining the consistency of finish specific parameters are defined to obtain dull fish on dead light temper (DLT) material. Finish Consistency obtained for all the products, since the products are unpainted.
[035] The method includes following steps-
1. Chemical analysis of melt is checked at Various stages of Process as per the Grade requirement.
2. Hot rolling will be done for the required Slab length, width and weight.
3. Hot rolled coils are annealed, shot blasted and pickled.
4. Cold rolling will be done for the thickness slightly higher (~0.10mm) than required thickness as per standard operating practice.
5. Next, Coil rolled coils are annealed and pickled in the continuous annealing and pickling line.
6. Dull finish is imparted on the bottom surface of the cold rolled, annealed and pickled coil in single pass ensuring thickness and finish as per the requirement.
7. Coils will be skin passed to obtain the required flatness.
8. Coils found which meets the requirement will be cut in to specified size in the finishing lines.
9. Packaging will be done as per the requirement.
[036] Numerous modifications and adaptations of the system of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the true spirit and scope of this invention. ,CLAIMS:WE CLAIM:
1. A dull finish parameters composition with dead light temper (DLT) on the exteriors/ side wall of the coaches comprises developed on austenitic stainless steels (SUS 301L) characterized in that Carbon (C) 0.030; Silicon (Si) 1.0, Magnese (Mn) 2.0; Phosphorous (P) 0.045; Sulphur (S) 0.030; Nickel (Ni) 6.0- 8.0; Chromium (Cr) 16.0-18.0; Nitrogen (N) 0.20.
2. The dull finish parameters composition with dead light temper (DLT) on the exteriors/ side wall of the coaches, as claimed in claim 1, wherein the surface condition having lower reflectivity by cold rolling with etched rollers and is applicable for the DLT grade.
3. The dull finish parameters composition with dead light temper (DLT) on the exteriors/ side wall of the coaches, as claimed in claim 1, wherein the Glossiness (Gu) 35 ±5 and surface roughness (Ra) in microns is 4.50 ± 0.5.
4. The dull finish parameters composition with dead light temper (DLT) on the exteriors/ side wall of the coaches, as claimed in claim 1, wherein the proof stress (N/mm2) 345- 485; tensile strength (N/mm2) 690- 860; elongation (%), (on 50mm GL) 40.
5. The dull finish parameters composition with dead light temper (DLT) on the exteriors/ side wall of the coaches, as claimed in claim 1, wherein the bend angle180º at Inside Radius ½ t.
6. The method of preparing the dull finish composition for metro coaches, as claimed in claim 1, wherein the composition provides consistency in gloss values and surface roughness values.
7. The method of preparing the dull finish composition for metro coaches includes following step-
a) Chemical analysis of Melt is checked at Various stages of Process as per the Grade requirement.
b) Hot rolling for the required Slab length, width and weight.
c) Hot rolled coils are annealed, shot blasted and pickled.
d) Cold rolling for the thickness slightly higher (~0.10mm) than required thickness as per standard operating practice.
e) Next, Coil rolled coils are annealed and pickled in the continuous annealing and pickling line.
f) Dull finish is imparted on the bottom surface of the cold rolled, annealed and pickled coil in single pass ensuring thickness and finish as per the requirement.
g) Coils are skin passed to obtain the required flatness.
h) Coils meeting the requirement are cut in to specified size in the finishing lines.
i) Packaging as per the requirement.