Square & Rectangular Bloom CCM: Advanced Technology for High-Quality Steel Blooms

Overview

A square bloom CCM and rectangular bloom CCM are designed to continuously cast large-section blooms with stable internal quality and consistent surface performance. For steelmakers producing high carbon steel, alloy steel, bearing steel, and spring steel, bloom casting quality directly influences downstream rolling yield, mechanical properties, and defect rates.

This article introduces an extra square and rectangular bloom bloom continuous casting machine configuration and its key process technologies—especially electromagnetic solutions, precision level control, dynamic cooling, and soft/heavy reduction—to help metallurgical plants improve bloom integrity while maintaining operational flexibility.

Technical Parameters (Reference Range)

Curvature (radius): R10m–R16m
Application section: 300mm × 300mm to 500mm × 600mm
Casting speed: 0.2–1.0 m/min

These parameters support a wide production window—from crack-sensitive grades requiring conservative cooling to higher-throughput grades where stable mold behavior and secondary cooling efficiency become decisive.

Typical Steel Grades and Why Bloom Quality Matters

A bloom CCM often targets grades where internal cleanliness and segregation control are critical:

• High carbon steel: more sensitive to thermal stress, corner cracking, and segregation banding

• Alloy steel: requires tighter chemistry and temperature management to avoid internal defects

• Bearing steel: demands excellent internal soundness, low segregation, and stable structure

• Spring steel: needs consistent microstructure and surface quality to prevent fatigue failures

For these grades, bloom quality issues often originate from:

• unstable superheat and tundish temperature drop

• mold level fluctuation causing oscillation marks or slag entrapment

• insufficient or non-uniform secondary cooling leading to surface cracks

• poor reduction strategy causing center porosity and macro-segregation

This is why advanced technologies such as tundish electromagnetic heating technology, whole-process protective casting technology, EMS systems, and dynamic soft reduction and heavy reduction are commonly adopted in modern bloom casters.

Advanced Technologies and How They Improve Bloom Quality

1) Tundish Electromagnetic Heating Technology

Purpose: stabilize tundish temperature and reduce superheat fluctuation.
Why it matters: large-section blooms are sensitive to temperature instability—too high superheat can increase segregation; too low superheat can cause nozzle clogging, level instability, and inclusions.

Benefits in practice

• better temperature consistency from ladle to mold

• improved casting stability during long sequences

• helps maintain target casting speed without quality compromise

2) Whole-Process Protective Casting Technology

Purpose: minimize re-oxidation and inclusion pickup from tundish to mold.
In bloom casting, inclusion control is essential for bearing and spring steels. Whole-process protective casting typically includes shielding, optimized refractory and flow control, and stable powder behavior.

Benefits

• reduces re-oxidation risk and inclusion-related defects

• improves surface cleanliness and internal purity

• supports stable mold powder performance and lubrication

3) Mold Level Control Technology

Purpose: keep mold level stable under changing flow and temperature conditions.
Mold level stability reduces meniscus turbulence and slag entrapment—both common causes of surface and subsurface defects.

What good control enables

• stable lubrication and heat transfer

• fewer oscillation-mark abnormalities

• reduced breakout risk during speed changes

4) Mold Electromagnetic Stirring (M-EMS)

Purpose: optimize flow pattern, promote uniform solidification, and reduce surface/internal defects.
M-EMS can improve strand shell growth uniformity and reduce local hot spots that lead to cracks.

Typical quality gains

• improved structure uniformity near surface/subsurface

• reduced bubble/particle capture tendency at the meniscus

• better corner quality for square and rectangular sections

5) Final Electromagnetic Stirring (F-EMS)

Purpose: improve center quality near the final solidification zone.
F-EMS supports cleaner center structure and helps reduce centerline segregation and porosity—especially important for bearing steel and alloy grades.

Benefits

• improved center density

• reduced centerline segregation tendency

• supports downstream rolling quality consistency

6) Out-In Double Cylinder Hydraulic Servo Oscillation System

Purpose: provide accurate oscillation waveform and stable mold lubrication.
Servo oscillation helps maintain consistent friction conditions and reduces breakout sensitivity—particularly useful when casting speed varies from 0.2 to 1.0 m/min.

Advantages

• more precise oscillation control and repeatability

• improved surface quality and fewer lubrication-related defects

• supports stable operation across multiple steel grades

7) Dynamic Secondary Cooling Technology

Purpose: adjust cooling intensity in real time to match casting speed, steel grade, and superheat.
Large bloom sections require balanced cooling to avoid surface cracks while ensuring sufficient shell growth for safety.

What “dynamic” means

• cooling water distribution and intensity can adapt to casting conditions

• temperature gradients can be managed to reduce corner and face cracking

• supports stable metallurgical length control

8) Dynamic Soft Reduction and Heavy Reduction

Purpose: reduce center porosity and segregation by applying controlled reduction at the appropriate solid fraction zone.
For large blooms, shrinkage and segregation are common challenges. Dynamic reduction strategies target the right timing and reduction amount.

Key outcomes

• improved center density and lower porosity

• reduced macro-segregation and centerline defects

• better downstream rolling yield and fewer internal defect rejections

Process Logic: How These Technologies Work Together

A high-performance square bloom CCM / rectangular bloom CCM is not defined by one feature, but by how systems cooperate:

1. Stable tundish temperature (electromagnetic heating) supports consistent flow and shell formation.

2. Protective casting reduces inclusions and improves cleanliness.

3. Mold level control + servo oscillation stabilizes meniscus behavior and lubrication.

4. M-EMS + F-EMS improves structure uniformity and center quality.

5. Dynamic secondary cooling prevents cracking while maintaining safe shell thickness.

6. Dynamic soft/heavy reduction addresses center porosity and segregation at the right location.

This integrated approach is especially valuable for bearing steel and spring steel, where defect tolerance is low.

What to Evaluate When Selecting a Bloom Continuous Casting Machine

If you are planning a new bloom caster or upgrading an existing line, focus on these decision points:

• Target section range (e.g., 300×300 to 500×600) and future expansion needs

• Steel grade mix (high carbon, alloy, bearing, spring) and crack sensitivity

• Temperature strategy (whether tundish electromagnetic heating is needed for long sequences)

• Inclusion control level (protective casting design, tundish flow control concept)

• Automation and closed-loop control (mold level, cooling, reduction, speed coordination)

• Reduction capability (soft reduction and heavy reduction design, control accuracy)

• Maintenance accessibility (oscillation system service, EMS equipment layout, segment exchange time)