Beam blank casting is a mature process born in 1968 [1]. Around 60 casters has been installed since. In this paper a thorough review of the literature on defects in beam blanks is carried out. The focus is on the formation mechanism and the solutions proposed to decrease their occurrence. Surface defects included are longitudinal cracks and transverse cracks. Internal defects are blowholes and solidification cracks. The review includes the techniques used to investigate the defects: metallographical characterizations, CFD, thermodynamical and thermomechanical modelling, etc. The measures taken have to do with changes in casting system (i.e. SEN design), mold design, secondary cooling modifications and regulation, strand support.

1. A Review of Defects in Beam Blank
Casting and the Measures Proposed for
their Elimination
Jorge Madias (1), Cristian Genzano (1), Marco Oropeza (2), Carlos Moss (2)
(2) Gerdau Corsa, Ciudad Sahagun, Mexico
(1) metallon, San Nicolas, Argentina

2. Content
Introduction
Surface defects
Internal defects
Conclusions

3. Introduction
metallon
Consulting & training company based in San Nicolas,
Argentina
Technical assistance
Short courses
Met lab services
Library services
Gerdau Corsa Sahagun
Start-up 2015
Consteel EAF, LF, billet/bloom/beam blank caster, universal
mill
1.000.000 tpy crude steel capacity
700.000 tpy rolled products capacity

4. Introduction
 Beam blank casting
Mature process, born in 1968
≈60 casters installed worldwide
Focus of the paper
Defects formation mechanism
Solutions proposed to decrease their occurrence
Changes in casting system (i.e. SEN design)
Mold design
Secondary cooling modifications and regulation
Strand support
Techniques used to investigate the defects
Metallographic characterizations
CFD, thermodynamical and thermomechanical modelling
Plant tests

5. Introduction
Three casting modes
Open casting (metering nozzles)
Semi submerged casting
(metering nozzles and funnels)
Semi submerged casting
(two or one SEN)

6. Introduction
Three casting modes: advantages and drawbacks
Casting type Advantages Drawbacks
Open casting Low cost: No need for SEN and
casting powder
High productivity: possibility of
automatic metering nozzle change
Splashing: cold drops
Reoxidation: macroinclusions, trapped
scum
Oil lubrication: Pin holes; risk of cracks
due to higher heat transfer
Al-killed steel not feasible
Semi submerged
casting
Less splashing
Less reoxidation
Less pin-holes
More control of heat transfer
Higher cost (funnel and casting powder)
Submerged
casting
No splashing: no cold drops
No reoxidation: no macroinclusions
Casting of Al-killed steels
Higher control of heat transfer (less
risk of cracking)
Higher cost (Stopper rod/ slide gate,
SEN and casting powder)
Lower productivity (limited by SEN life)

7. Introduction
Mold
Tubular: small and medium sections
Plates: larger sections
Possibility of using plate mold in a mold
jacket for tubular mold

8. Introduction
Plate molds
Wide faces: Holes and spacers
Narrow faces: Slots

9. Introduction
Plate molds
More alternatives to manage water cooling
Slots, holes with spacer, full hole, distance between
holes, distance to hot face
More rigidity of the assembly
Stability of transverse geometry of cooling
channels
Easy achievement of different taper modes
Higher cost

10. Surface defects
Pin holes
Usual for casting with metering nozzle with oil
lubrication
May be deleterious for the final product if
Concentrated in a particular zone (“nest”)
Deep enough as to not disappear in the reheating
furnace
Visible if in the first rolling steps the materials has free
spreading (it is not contained) somewhere
Almost scale-free in the beam blank, but then in the
reheating furnace the become filled with scale

11. Surface defects
Pin holes
Moisture in oil
Moisture pick-up in oil circuit)
Too high oil rate
Inhomogeneous transverse distribution
Too thick oil slot gap (more than 0.5 mm)
Partial obstruction of oil slot gap by splashing
Sudden variations in steel mold level
Use of pulsing bomb
Lack of deoxidation
Electromagnetic stirring helps in pinhole elimination

12. Surface defects
Bleeding
As in billets, this defect occurs when small strand
breakout takes place, healing immediately, without
metal loss
Annular stress may promote bleeding
670 mm wide beam blank
Bleeding in the inner surface of the wing

13. Surface defects
Bleeding
Classic formation mechanism

14. Surface defects
Trapped scum
Typical of open casting
Due to thorough
reoxidation of the liquid
steel in contact with air
and oxidizing slag
Usually a liquid
manganese silicate, but if
a solid precipitates,
viscosity increases and
entrapment may occur
If silicon content is too
high (due to a low Mn/Si
ratio), silica precipitation
occurs,
If aluminum wire injection
in the mold is practiced,
alumina precipitation may
occur if it is excessive or
it is not in the right point

15. Surface defects
Casting powder entrapment
Similar to scum entrapment
Higher viscosity may occur in this case through
Alumina pick-up
Reduction reactions between elements in the steel
and oxides in the casting powder
Example, dissolved titanium reacting with silica in the slag
Enhanced through turbulence
Excessive electromagnetic stirring
Short SEN / funnel submersion

16. Surface defects
Network cracks
Related with high copper content in the steel
High copper scrap charge
Where gap between strand and mold becomes
large, grain size increases and if copper content is
high, network cracking may occur
Rolled H Beam, Dragon Steel Corporation

17. Surface defects
 Longitudinal facial cracks
 Fairly common for beam blanks
 Formed in the mold
 Similar to longitudinal cracks in slabs and blooms
 In rolled product, its metallographic features are
 Internal oxidation (as polished, no etching)
 Decarburization (etching with Nital 2%)
 Oxygen penetration (hot etching with alkaline sodic chromate)
 Influencing factors
 Chemistry of the liquid steel
 Properties of the casting powder
 Deviations of caster radius caused by mold oscillation
 Primary cooling: Water flow rate and temperature
 Secondary cooling: Water flow rate
1050 mm wide beam blank
Longitudinal crack between web and fillet

18. Surface defects
Longitudinal facial
cracks
Steel chemistry
Sulphur content
Carbon content
Peritectic
transformation needs
to be avoided
POSCO scarfed
beam blanks
corresponding to
2,000 heats
0.12 – 0.13%
carbon the more
sensible range
Stahlwerke Thüringen
C 0.08% max

19. Surface defects
Longitudinal facial cracks
Casting powder
Stahlwerke Thüringen
 Low viscosity mold flux
for small beam blanks at
low speed<1 m/min)
 “Soft” cooling at
meniscus level was
obtained
 Lower capacity for
infiltration and lubrication
compensated by low
viscosity
JFE Steel Mitsushima
 Different set of casting
conditions
 Low viscosity gave place
to longitudinal cracks
(among other reasons)

20. Surface defects
Longitudinal facial cracks
Casting powder
In cold zones of the meniscus (i.e., close to the
SEN), casting powder may reach the limit of its
performance and give place to surface cracks
Entrapment of non-molten
mold flux; distorted oscillation
marks, small depression
Longitudinal facial crack in the
web, due to thermal shock by
direct contact with the mold
1050 mm wide beam blank

21. Surface defects
Longitudinal facial cracks
Casting speed
Posco experience
As the casting speed increases
Solidifying shell is thinner
Heat flow increases
Strain is larger
Result: More cracks

22. Surface defects
Longitudinal facial cracks
Secondary cooling
More secondary cooling intensity, more cracking risk

23. Surface defects
Longitudinal facial cracks
Secondary cooling
Extensive use of mathematical modeling
Jin Yi Iron & Steel: optimization of secondary cooling
to avoid these cracks
ANSYS for the thermo mechanical model
MATLAB for parameter optimization
Maanshan Steel: thorough modeling of secondary
cooling with the same purpose, taking into account
all the mechanisms involved in heat transfer

24. Surface defects
Longitudinal facial cracks
Summary of plant experiences
Company/Plant Year Corrective actions
JFE Steel Mizushima 1975 Decrease sulphur; increase mold flux viscosity; improve mold alignment
JFE Steel Mizushima 1981 Decrease sulphur; adequate mold flux; minimize mold misalignment; adequate
primary cooling; soft secondary cooling in first segments; better distribution of
sprays in transverse section
Stahlwerke Thüringen 1998 High basicity low viscosity casting powder
JFE Steel Fukuyama 1996 Decrease sulphur; decrease secondary cooling flow rate
Stahlwerke Thüringen 1997 C<0.08% (Mn 0.60 to ensure mechanical properties)
Posco 2002 Avoid 0.12-0.13% C; lower casting speed
Stahlwerke Thüringen 2002 Avoid 0.12% C
Jinyi Iron & Steel 2013 Lower water flow rate in all secondary cooling segments
Maanshan Steel 2014 More secondary water to fillet; less to wing ends and web center. -10% segment
1; -7% segment 2

25. Surface defects
Longitudinal facial cracks
Corrective actions
Metallurgy
Low sulphur
Avoid peritectic transformation
Mold flux
High basicity
Even heat transfer
Mold design
To avoid longitudinal cracks in the shoulder
Secondary cooling
Less water, mostly for the first segments
Better transverse distribution

26. Internal defects
Blowholes
Depending on the root
cause, they may be
concentrated in the first
heat of the sequence or
in some given heat, or
all along the sequence
Start: close to the beam
blank surface, when
there is enough gas
segregation to the
interdendritic spaces
End: when somewhere
below the meniscus, the
ferrostatic pressure is
higher than the gas
pressure

27. Internal defects
Blowholes
Excess of gases dissolved in the steel (oxygen,
nitrogen, hydrogen), enough to produce a bubble
Compromise between clogging and blowholes

28. Internal defects
Blowholes
Typical industrial cases
High oxygen
Lack of deoxidation (coordination, slag carry over)
High oxygen and nitrogen
First heat of the sequence
High hydrogen
Moisture in new lining of ladle or tundish
High nitrogen
Ladle with long treatment, when nitrogen is used for stirring

29. Internal defects
Blowholes
Dragon Steel Corp. case
Casting with metering nozzle
80 kg Al addition during tapping
40 kg CaFe to get O<10 ppm
Oxygen injection in tundish if temperature too low
Thorough study of LMF and caster variables
High moisture in tundish repair refractory material

30. Internal defects
Web central cracks
Equivalent to centerline
segregation in slabs
Not enough support length
Insufficient secondary
cooling
Bulging, and in severe
cases, an internal opening
in the web
Rolled H beam
Central segregation
Crack formation
Some countermeasures
Use of roll checker
Equipment for segment
alignment

31. Internal defects
Inner crack in wing end
May promote strand breakout
Resemble off-corner cracks in billets and slabs

32. Internal defects
Inner crack in wing end
JFE Steel Kurashiki case
Strand breakout in some heats
Improvement plan
Solution: optimization of mold taper in wing ends
Study Objective
Observation of breakout boxes Research solidification in mold; find cause
Solidification macrostructure Mechanism of formation of inner cracks in wing end
Sulphur addition test Measurement of shell thickness in normal operation
Mold temperature Estimation of heat flow in several parts of the mold

33. Internal defects
Web central cracks
JFE Steel Mitzushima
Caster 12.5 m radius,
funnel casting
400 x 460 x 120 mm
287 x 560 x 120 mm
Influence of sulphur
content and casting
speed
Solutions
Intensive spray cooling
on the web portion
Strict maintenance of
roll gap

34. Conclusions
Beam blank casting is an established process with a
50 years history
It is not free of surface and inner defects
Some of them share features with billet defects; other
has more to do with slab defects
 The complex shape induce specific solidification
defects
The occurrence of defects requires carrying out
improvement plans to make them minimal
Defect characterization is important
Simulations may help to elucidate the formation
mechanism and to suggest corrective measures

35. Jorge Madias (1), Cristian Genzano (1), Marco Oropeza (2), Carlos Moss (2)
(1) metallon, San Nicolas, Argentina
(2) Gerdau Corsa, Ciudad Sahagun, Mexico