Warm rolling is a steel processing technique that involves rolling between the temperatures of hot and cold rolling, typically between 500-800°C. This provides benefits over traditional hot or cold rolling such as lower energy costs, reduced roll wear, and elimination of annealing. The document discusses various studies that have examined the effects of warm rolling temperature and strain rate on the microstructure and properties of low carbon and electrical steels. Warm rolling was shown to produce fully recrystallized microstructures at higher temperatures but deformation bands at lower temperatures. It can also develop cube recrystallization textures useful for electrical steel applications.

1. WARM ROLLING
G.SUDHAKAR
Phd(Material Engg)

2. The steel industries are greatly interested in WARM
ROLLING:
1. Due to the better properties and lower cost of the
finished product.
2. Steel working within the range intermediate
between hot and cold rolling represents a more
economical operation, having that hot rolling implies
considerably higher costs in order to conserve the
high temperature.
3. Also, in cold rolling, the working loads and roll wear
are high, which also reflect in high costs. Besides,
the holding time required for the hot strip to cool
down to room temperature before cold rolling is also
reduced.

3. 1. Conventional hot rolling takes place at temperatures
above the austenite to ferrite transformation while warm
or ferritic rolling takes place below the two phase (α+γ)
region
2. The practice of rolling in the upper ferritic region instead
of in the austenitic region has been termed as warm
rolling or, alternatively, ferritic rolling
3. Warm rolling has gained interest as means of cutting down
costs and of extending the application range of hot rolled
products. This requires diminishing the temperatures of
the whole process from 1250-850°C to approximately
1100-700°C.
4. Because hot working requires much expensive thermal
energy, there has been a drive to work at lower
temperatures. Working at lower tempera-ture, warm
working, can produce material close to its final
shape and reduce or eliminate cold working
which requires higher working forces and die-press-ure .
Further heat treatment in some applications may
also be avoided
5. Warm (ferritic) rolling has the potential to
broaden the product range and decrease the
cost of hot-rolled strip materials

4. Microstructural and textural development in an extra low
carbon steel during warm rolling

5. 1. completely recrystallized ferrite grains of almost
polygonal shape are obtained after rolling at the high
temperature of 800 °C.
2. At 700 °C the microstructure shows recrystallized
areas, pancake shaped grains and dark patches of
deformation bands indicating incomplete
recrystallization
3. deformed and elongated ferrite grains with profusion
of deformation bands are obtained at lower rolling
temperatures (600 and 500 °C);
Higher magnification SEM micrographs of the samples
reveal the deformation bands within grains clearly
Evidently, the density of deformation bands is
substantially high when rolling temperature is low and it
decreases rapidly with increase in the rolling temperature,
and ultimately becomes effectively zero at 800 °C.

6. Effects of hot and warm rolling on microstructure, texture
and properties of low carbon steel
SIBM (strain induced boundary migration):
The mechanism of bulging or migration of part of a pre-
existing grain boundary to the interior of a more deformed
grain, leaving behind a region virtually free of dislocations
WARM ROLLING TEMPERATURE

7. MICROSTRUCTURAL DEVELOPMENT DURING
WARM ROLLING OF AN IF STEEL
WARM ROLLING
TEMPERATURE
500~800°C
STRAIN RATE
Modelling the warm rolling of a low carbon steel
C:0.048
Mn:0.4
Si:0.04
P:0.06
S:0.02
Cr:0.05
Nb:0.0
N:0:0.003
WARM ROLLING TEMPERATURE 650◦C
the mean strain rates of 10−3,10−2and 10−1 s−1

8. Effect of Rolling Temperature on the Deformation and
Recrystallization Textures of Warm-Rolled Steels
ELC IF Ti
C: 0.020 0.004
Mn: 0.12 0.15
P: 0.004 0.005
S: 0.007 0.010
Si: 0.006 0.006
Cr: 0.071 0.065
Al: 0.048 0.041
N: 0.0067 0.0037
Ti: 0.0 0.062
Nb: 0.0 0.0
WARM ROLLING TEMPERATURE (650 °C to
800 °C)
STRAIN RATE

9. (d) and (e), for 40% and 60% at 600C, respectively.
(b) and (c) show the results for 40% and 60% warm rolling at
400C and

10. Development of Through-Thickness Cube
Recrystallization Texture in Non-oriented
Electrical Steels by Optimizing Nucleation
Environment
Ning Shan, Jinlong Liu, Yuhui Sha, Fang Zhang & Liang Zuo
Metallurgical and
MaterialsTransactionsA volume 50, pages2486–2494 (2019)

11. Fig. 1—Warm rolling microstructure and texture of Fe-2.1 wt pct Si sheets: (a) microstructure under 70 pct rolling reduction, (b) constant u2 = layers
under 70 pct rolling reduction, and (c) orientation densities of main texture components at different rolling reductions. 45 deg section of ODFs at different
Fig. 2—(a) Constant u2 = 0 and 45 deg sections of ODFs at S = 0.5 layer under 70 pct rolling reduction, (b) orientation densities of main texture components at different thickness layers under
70 pct rolling reduction, and (c) orientation densities of main texture components under different rolling reductions in Fe-2.1 wt pct Si sheets after annealing at 1123 K (850 °C) for 10 min.
Fe-2.1 wt pct Si ingots,
0.01 wt pct C,
2.1 wt pct Si,
0.2 wt pct Mn,
0.002 wt pct Al,
0.004 wt pct S,
0.017 wt pct P,
and balance Fe

12. Fig. 3—(a) Orientation image maps, (b) constant u2 = 0 and 45 deg sections of ODFs, and (c) number fraction and average grain size of main texture components
at S = 0 layer in Fe-2.1 wt pct Si sheets after annealing at 1273 K (1000 °C) for 10 min.
Fig. 4—(a) Orientation image maps and (b) local enlarged maps in Fig. 4(a) and corresponding u2 = 45
deg section of ODFs of cube recrystallized grains and surrounded deformed matrices in 7 pct recrystallized Fe-2.1 wt pct Si sheets.

13. Fig. 5—(a) Orientation image maps and (b) constant u2 = 0 and 45 deg sections of ODFs of recrystallized grains within different thickness layers in 44 pct recrystallized Fe-2.1 wt pct Si sheets.
Fig. 6—(a) Orientation image maps and corresponding constant u2 = 45 deg section of ODFs of cube recrystallized grains and surrounded deformed matrices and (b) orientations of
deformed matrices in Fig. 6(a) marked in the u2 = 45 deg section in 44 pct recrystallized Fe-2.1 wt pct Si sheets.
Fig. 7—(a) Area fraction and (b) number fraction of main texture components of recrystallized grains in 44 pct recrystallized Fe-2.1 wt pct Si sheets.

14. Fig. 8—(a) Orientation image maps and (b, c, d) corresponding local enlarged maps in Fig. 8(a) and constant u2 = 45 deg section of ODFs of cube micro-regions retained at (b, c)
transition bands and (d) grain boundaries and surrounded deformation bands at S = 0 layer of warm rolled Fe-2.1 wt pct Si sheets under 70 pct reduction.

15. Fig. 9—Schematic representation of the formation of through-thickness cube texture during primary recrystallization:
(a) warm rolling microstructure,
(b) formation of cube grains at the boundaries of deformation bands with orientation in Regions I and II in the early stage of recrystallization, and
(c) formation of cube texture after primary recrystallization.

16. Induction Melted and Homogenized at 1473 K (1200 °C) for 120 minutes
RFT :1223 K (950 °C)
1303 K (1030 °C) for 10 minutes
773 K (500 °C)
Annealed in Ar atmosphere
at 1123 K (850 °C) for 10 minutes
TEMPERATURE °C
TIME hrs
Rolling reductions of 60, 70, 80, and 90 pct
1273 K (1000°C) for 10 minutes
44 pct recrystallized fraction
973 K (700 °C) for 3 minutes
80 to 3.5 mm
Rolling Reduction of 82% yields 0.6mm
For 70 pct Rolling reduction
0.01 wt pct C, 2.1 wt pct Si, 0.2 wt pct Mn, 0.002 wt pct Al,
0.004 wt pct S, 0.017 wt pct P, and balance Fe
7 pct recrystallized fraction