hot and cold rolled sections -bms

hot and cold sections - building material science

1. Building Material and
Sciences-IV
Assignment-4
HOT AND COLD
ROLLED SECTIONS
Submitted by:SHRUTI GARG
B.Arch 2nd year-A

2. Q.1) Explain hot &; cold rolled sections. With Examples.
A.1)Hot rolled sections:• Hot rolling is a millprocess which involves
rolling the steel at a high temperature, which isabove the steel’s
recrystallization temperature.
• When steel is above the recrystallization temperature,it can be shaped
and formed easily, and the steel can be made in muchlarger sizes.
• When the steel cools off it will shrink slightlythus giving less control on
the size and shape of the finished product
• Hot rolling allows large deformations of the metalto be achieved with a
low number of rolling cycles.
• Used in the welding and construction trades to makerailroad tracks and
I-beams
• Hot rolling is primarily concerned with manipulatingmaterial shape and
geometry rather than mechanical properties.
• Hot rolling uses large pieces of metal, such asslabs or steel billets, and
heats them above their recrystallization temperature.The metal pieces are
then deformed between rollers creating thin crosssections.
Cold rolled sections:
• Cold rolled steel is essentially hot rolled steelthat has had further
processing.
• The steel is processed further in cold reductionmills, where the material is
cooled (at room temperature) followed by annealingand/or tempers rolling.
• This increases the yield strength and hardness ofthe metal. This is done
by introducing defects into the crystal structureof the metal creating a
hardened microstructure which prevents further slip.

3. • Cold rolled steel is manufactured at temperatures below its
recrystallization temperature, typically at around room temperature.
Because the steel is manufactured at a much lowertemperature, there’s no
need to worry about the steel shrinking or changingform or appearance.
• The cold rolled steel end products like cold finishedsteel bar have a
much smoother appearance and may have square cornersmore accurate
in dimension and finish.
• Cold rolled steel is much more preferred in themachining world where the
quality of the steel is an important factor of thequality of the final product,
and the appearance of the steel is also an importantfactor. • Cold finished
bars are typically harder to work with than hot rolleddue to the increased
carbon content.
• Examples of cold rolled steel products include;bars, strips, rods and
sheets.

4. Q.2) Difference between both the rolling techniques.
A.2)

5. Q.3) Explain advantages & disadvantages of hot & cold rolled
sections.
A.3) Following are the advantages and disadvantagesof hot and cold
rolled sections:
Q.4) Explain the types of sections which are madeby rolling
sections.
A.4) Following types of sections are made by rollingsections:
1. Rolled Channel Sections
• The channel section or C- section consists of twoequal flanges
connected to web at both ends.
• Channel sections are extensively used in steel framedstructures.

6. 2. Rolled angle sections
• Angle sections are manufactured in “L” shape. Itcontains two legs.
• Angle section with similar leg dimension- equalangle sections
• Angle section with different leg dimension- unequalangle sections
• Angle sections are widely used for roof truss constructionsand for filler
joist floors.
3. Rolled T-sections
• T section consists of a flange and web arrangedin “T” shape. Two angle
sections can also be joined to get T section
• They are used in steel roof trusses to form builtup sections.

7. 4. Rolled square bars
• Square bars contain square cross sections
• The sides of the square cross section ranges from5 mm to 250 mm.
• Widely used for gates, windows, grill works etc.
5. Rolled round bars
• Round bars contain circular cross sections
• Round bars are available in various diameters rangingfrom 5 mm to 250
mm.
• Used as reinforcement in concrete and steel grillwork etc.

8. 6. Corrugated sheets
• Plain steel sheets are passed through machineswhich produce bends by
pressing them called corrugations.
• These sheets are used for roof coverings.
7. Rolled flat bars
• Flat bars are designated with width of the barwhich varies from 10 mm to
400 mm. The thickness of flat bars will be from 3mm to 40 mm.
• Flat bars are used for gates, windows, grill worksetc.
8. Rolled steel plates
• Steel plates are well used items in steel structures.
• They are designated with their thickness which isvarying from 5 mm to 50
mm.
• They are used for connecting steel beams, tensionalmembers in roof
truss etc

9. 9. Expanded metal
• Expanded metal sheets are made from mild steel sheets.Which are cut
through machine and expanded.
• Generally, diamond shaped mesh is observed.
10.Ribbed mild steel bars
• Ribbed bars can also be produced from mild steel.These are look-alike
HYSD ribbed bars but these bars are not recommendedby any code and
they also have very less strength compared to HYSDbars.

10. 11.Ribbed HYSD bars
• Ribbed HYSD bars are made of high yield strengthsteel. Ribs are
nothing but projections produced on bars by cold twistingof the bar in hot
rolled condition. Twist is made as per standard requirements.
• Extensively used as main reinforcement materialsin all concrete works
like bridges, buildings, precast concrete works, foundations,roads etc.
• They are available in many sizes varying from 6mm to 50 mm diameter.
12.Ribbed TMT bars
• TMT bars are manufactured by a special techniquein which the red-hot
steel bars are suddenly cooled down by spraying wateron it. So, the
surface of the bar gets cooled down and the innerside or core of the bar is
still in hot condition.
• By this combination of different temperatures, thebar gains more yield
strength and exhibits good elongation at ultimatefailure.
• Copper, phosphorus and chromium etc. are addedin the manufacturing
process of TMT bars which improves its corrosion resistance.

11. 13.Welded wire fabrics
• Welded wire fabrics are a series of mild steel barswhich are arranged
perpendicular to each other and welded at all intersections.
• These are used as reinforcement for floor slabs,small canal linings,
pavement’s etc.
Q.5) Give suitable sketches for the raw material &finished product
made through rolling section & cold forming.
A.5)Cold rolling process:
• Cold rolling process involves using hot-rolledsteel coil as raw material
MANUFACTURING PROCESS:COLD ROLLED SECTION

12. MANUFACTURING PROCESS:HOT ROLLED SECTION