Difference between DNV E690 and DNV E400 steel plate - Knowledge

DNV E690 and E400 are high-strength shipbuilding/offshore steel plates certified by DNV (Det Norske Veritas), with the number indicating minimum yield strength (690 MPa for E690, ~400 MPa for E400), used for critical marine structures like ship hulls, platforms, and offshore components requiring exceptional strength, toughness, and weldability, often delivered in quenched & tempered (QT) or TMCP conditions for superior performance. E690 is an extra-high strength grade, while E400 falls into the high-strength category, both featuring controlled chemistry and stringent mechanical properties for harsh marine environments.

Chemical Composition

DNV E420 extra high Strength Chemical Composition
Grade	The Element Max (%)
Grade	C	Si	Mn	P	S	Al	N
DNV E420	0.20	0.10-0.55	1.7	0.030	0.030	0.015-0.08	0.020
	Nb	V	Ti	Cu	B	Ni	Mo
	0.02-0.05	0.04-0.10	0.02		0.005

DNV E690 extra high Strength Chemical Composition
Grade	The Element Max (%)
Grade	C	Si	Mn	P	S	Al	N
DNV E690	0.20	0.10-0.55	1.7	0.030	0.030	0.015-0.08	0.020
	Nb	V	Ti	Cu	B	Ni	Mo
	0.02-0.05	0.04-0.10	0.02		0.005

Mechanical Property

DNV E420 extra high general strength property
Grade		Mechanical Property			Charpy V Impact Test
Grade	Thickness	Yield	Tensile	Elongation	Degree	Energy 1	Energy 2
DNV E420	mm	Min Mpa	Mpa	Min %	-40	J	J
	t≤50	420	530-680	18%		28	42
	50＜t≤70	420	530-680	18%		28	42
	70＜t≤150	420	530-680	18%		28	42
Note: Energy 1 is transverse impact test, Energy 2 is longitudinal

DNV E690 extra high general strength property
Grade		Mechanical Property			Charpy V Impact Test
Grade	Thickness	Yield	Tensile	Elongation	Degree	Energy 1	Energy 2
DNV E690	mm	Min Mpa	Mpa	Min %	-40	J	J
	t≤50	690	770-940	14%		46	69
	50＜t≤70	690	770-940	14%		46	69
	70＜t≤150	690	770-940	14%		46	69
Note: Energy 1 is transverse impact test, Energy 2 is longitudinal

DNV E690 Steel Plate

Strength: Minimum yield strength of 690 MPa, an extra-high strength grade.

Application: Hull construction, offshore platforms, critical structural parts needing extreme load resistance.

Properties: High tensile strength, excellent toughness, and ductility, often martensitic.

Delivery: Typically supplied in Normalized, TMCP (Thermo-Mechanical Controlled Processing), or Quenched & Tempered (QT) conditions.

DNV E400 Steel Plate (or similar strength levels like E420/F420)

Strength: Around 400 MPa minimum yield strength, categorized as high-strength steel.

Application: General shipbuilding, ship repair, offshore structures where high strength is needed but not the extreme levels of E690.

Properties: Good combination of strength and toughness, suitable for marine environments.

Delivery: Similar heat treatments as E690 (Normalized, QT, TMCP) to achieve desired properties.

Key Differences & Similarities

Strength: E690 is significantly stronger (690 MPa vs. ~400 MPa).

Application: Both for marine, but E690 for more demanding, higher-stress parts.

Classification: Both are DNV-certified steel grades for marine/offshore use.

Processing: Both benefit from controlled chemistry and specific heat treatments (like QT/TMCP) for optimal mechanical performance and weldability.