CRGO Grades Explained: How Indian Transformer Buyers Should Evaluate CRGO Steel

Cold Rolled Grain Oriented (CRGO) steel is not bought on name alone. In India, most procurement challenges arise not because CRGO is unavailable, but because buyers struggle to correctly evaluate grade, loss performance, thickness, and suitability for application. This gap between technical specification and commercial decision-making often leads to higher losses, rejected cores, or long-term efficiency penalties.

As India’s transformer industry moves toward stricter efficiency norms and competitive tendering, understanding CRGO grades has become a necessity rather than a technical luxury.

What “CRGO Grade” Really Means

CRGO grades are primarily defined by core loss values, measured in watts per kilogram (W/kg) at standardized conditions. Lower core loss directly translates to higher transformer efficiency and lower operating costs over the transformer’s life cycle.

Globally, CRGO grades are denoted using alphanumeric classifications such as:

• M3, M4, M5, M6

• Hi-B, Laser Scribed (LS), Domain Refined grades

However, in the Indian market, grades are often referenced indirectly through:

• Core loss values

• Thickness (0.23 mm, 0.27 mm, 0.30 mm)

• Application suitability (distribution vs power transformers)

This mismatch between global grade nomenclature and local buying practice is where confusion begins.

Thickness vs Core Loss: Why Both Matter

A common misconception is that thinner CRGO automatically means better performance. While thinner materials generally have lower losses, thickness alone does not define quality.

Common thicknesses used in India:

• 0.23 mm – Preferred for high-efficiency and star-rated transformers

• 0.27 mm – Widely used balance between cost and performance

• 0.30 mm – Older or cost-sensitive applications

Two CRGO sheets of the same thickness can still perform very differently depending on:

• Grain orientation quality

• Domain refinement

• Coating condition

• Manufacturing origin

This is why buyers increasingly evaluate CRGO based on tested loss values per kg, not just thickness or brand name.

Prime CRGO vs Secondary CRGO: Grade Evaluation Differences

Prime CRGO

Prime CRGO is mill-fresh material with:

• Certified test values

• Uniform coating

• Consistent magnetic properties

For utility-approved or export-oriented transformers, prime CRGO is often mandatory. However, availability is limited and lead times are longer.

Secondary CRGO

Secondary CRGO includes surplus, excess, or downgraded material that may still be technically usable.

In India, secondary CRGO is widely used, but grade evaluation becomes critical. Buyers must assess:

• Whether loss values sit within acceptable deviation

• If coating damage affects stacking factor

• Whether material is laser-treated or not

Well-classified secondary CRGO can deliver reliable performance when sourced transparently.

Why Core Loss “One Grade Up” Matters

In Indian CRGO trade, the phrase “core loss sits one grade above” is frequently used. This means the tested loss value is slightly higher than the nominal grade but still acceptable for certain applications.

For example:

• A material sold as equivalent to M3 but performing closer to M4

• Suitable for non-star-rated or internal-use transformers

Understanding this distinction allows buyers to optimize cost without compromising application requirements.

Laser Scribed vs Non-Laser CRGO

Laser scribed CRGO has refined magnetic domains, resulting in:

• Lower hysteresis loss

• Improved efficiency at operating flux density

However:

• Laser-treated material is costlier

• Mishandling can reduce its advantage

Not all applications require laser scribed CRGO. For many distribution transformers, properly selected non-laser grades perform adequately at lower cost.

Indian Buyer Challenges in Grade Selection

Indian transformer buyers face unique constraints:

• BIS-approved supplier limitations

• Inconsistent grade descriptions in the market

• Pressure to reduce initial cost while meeting efficiency norms

This has made grade literacy a commercial advantage rather than a purely technical one.

Buyers who understand CRGO grades can:

• Avoid overpaying for unnecessary specifications

• Reduce rejection rates during core assembly

• Improve long-term transformer performance

How Buyers Should Evaluate CRGO Before Purchase

A practical evaluation framework includes:

1. Confirming tested core loss values per kg

2. Matching grade suitability with transformer rating

3. Inspecting coating condition (especially for secondary CRGO)

4. Understanding stacking factor impact

5. Aligning material choice with tender or regulatory requirements

Relying solely on price per kg often leads to hidden efficiency costs later.

Role of Market Knowledge in CRGO Procurement

In a market where grades, availability, and pricing shift continuously, information accuracy becomes as important as material quality.

At S M Steels, we work closely with buyers to:

• Clarify grade positioning

• Explain realistic performance expectations

• Source both prime and secondary CRGO transparently

• Align material selection with application needs

Our approach focuses on technical suitability first, pricing second, ensuring buyers make informed decisions rather than reactive purchases.

Conclusion

CRGO grade selection is no longer optional knowledge for Indian transformer buyers. With tightening efficiency standards and constrained supply, understanding grades, loss behavior, and application suitability directly impacts profitability and compliance.

Buyers who invest time in grade evaluation position themselves better in a competitive and regulated market, while those relying on assumptions risk long-term operational costs.