2. HOT ROLLING PROCESS
• The starting material is usually large pieces of
metal, like semi-finished casting products, such as
slabs, blooms, and billets.
• In continuous casting, rolling mill is mostly integrated
to save energy.
• for larger work pieces gas- or oil-fired soaking pit
• for smaller work pieces induction heating.
• a finishing temperature is defined (50 to 100 °C
above the recrystallization temperature) If the
temperature does drop below this temperature the
material must be re-heated before more hot rolling.
3. HOT ROLLING PROCESS
• Approximately 96% of steel is continuously cast (the
remaining - ingots ).
• After hot rolling the cooling should be done
uniformly else residual stress is generated due to
shrinkage that affects the mechanical properties.
• Mill scale is the oxide layer formed on the surface
due to reaction with atmosphere at high
temperatures.
• Pickling is done with HCl to remove this scale.
4. TERMS RELATED TO HR COIL
• SPCC is a grade of commercial steel equivalent to
JIS G3141.
SPCC -SD/SB
SD = standard dull finish
SB = standard Bright finish
• SPHC : Steel Plate Heat treated Commercial quality
• HRB : Hot R
• U- oxidation unspecified
• A- aluminium killed
• K- silicon aluminium killed
• G- heat treatment and hot dipcoated
