R A|KR Grade A STEEL PLATE

KR Grade A (R A) is ordinary-strength shipbuilding plate under Korean Register rules. Gangsteel supplies KR Grade A for hull structures where A-class toughness is specified.

This page is a standalone technical article. For the primary overview on the original URL, see KR Grade E primary (original slug).

Ordinary-Strength Context

Grade A sits with B/D/E at 235 MPa yield. Select the letter from class requirements. Higher-strength A32/A36/D36 families are separate products.

Chemical Composition (Planning)

Element	KR Grade A (typical ordinary strength)	Notes
C	Thickness-dependent max	UR W11 / KR tables
Mn	Per rules	Often ≥2.5×C
Si	≤ 0.55 typical
P / S	≤ 0.035 typical
Deoxidation	Killed (as required)	Grade A practice per thickness

Mechanical Properties

Property	Value
Yield min	235 MPa
Tensile	400–520 MPa
Impact	+20°C (may be waived ≤50 mm per rules)

Applications

General hull plating and members in temperate service where class accepts Grade A. For colder toughness letters, see D/E or higher-strength D36/E36 pages.

Comparison

KR Grade E (−40°C) · KR D36 · KR D51

Impact Waiver Notes

Under IACS UR W11 practice, Grade A impact tests may be waived for limited thickness when rules allow. Do not assume waiver applies—cite the KR rules edition and thickness on the mill order. When waiver is not permitted, +20°C Charpy results appear on the certificate.

Z-Quality and Through-Thickness Properties

If the design requires Z25 or Z35 reduction-of-area properties for plated T-joints, state Z-quality explicitly. Ordinary Grade A chemistry alone does not guarantee Z performance.

Topic	Grade A note
Strength tier	235 MPa ordinary
Toughness	+20°C / waiver per rules
Vs D36	Different strength class

Frequently Asked Questions

What is KR Grade A steel plate?

KR Grade A (R A) is the ordinary-strength hull grade with the mildest toughness requirement in the A/B/D/E set—Charpy at +20°C, often waived for limited thickness under IACS UR W11 / KR rules.

When is Grade A acceptable instead of D or E?

Only when the hull design and class notation allow A-class toughness. Using A where D or E is required is a class non-conformance. Check the nesting list and class notes before substitution.

What are the strength levels for KR Grade A?

Minimum yield 235 MPa and tensile 400–520 MPa—the same ordinary-strength tier as Grades B, D, and E. Toughness temperature is the differentiator.

Is KR Grade A the same as AH36?

No. AH36 / A36 higher-strength grades target 355 MPa yield. Grade A is ordinary strength. Do not interchange based on the letter “A” alone.

What delivery condition is typical?

As-rolled, controlled rolled, or normalized depending on thickness and mill approval. State the required condition on the PO if the shipyard specification restricts options.

How does this page relate to KR Grade E?

This Grade A article previously shared the Grade E URL. The primary Grade E page remains at KR Grade E; this page is a standalone Grade A resource.

Ordering and Mill Certificates

State grade KR Grade A / R A, dimensions, quantity, delivery condition, optional NDT/PMI, and certificate (EN 10204 3.1 standard; 3.2 when third-party inspection is ordered). Gangsteel supplies export plate and related products with mill test certificates. Contact Gangsteel for stock and mill production RFQs.