Difference between LR EH46 and LR EH55 steel plate - Knowledge

LR EH46 is an extra-high-strength marine steel plate certified by Lloyd's Register (LR) . The "EH" designation signifies it is impact tested at -40°C, ensuring excellent toughness for Arctic and cold-environment applications . It has a minimum yield strength of 460 MPa and tensile strength ranging from 570 to 720 MPa, with minimum elongation of 19% for thicknesses up to 100mm . Impact energy requirements are minimum 46J (longitudinal) or 31J (transverse) at -40°C . The chemical composition is strictly controlled with carbon ≤0.20%, manganese ≤1.70%, and microalloying elements including Nb, V, and Ti . It is widely used for hull structures, offshore platforms, and demanding marine engineering projects.

LR EH55 is also an extra-high-strength marine steel plate certified by LR with impact toughness tested at -40°C . The "55" denotes a minimum yield strength of 550 MPa. It has a tensile strength ranging from 670 to 830 MPa and minimum elongation of 18% for thicknesses up to 100mm. Impact energy requirements are minimum 55J (longitudinal) or 37J (transverse) at -40°C . The chemical composition features similar strict controls with carbon ≤0.20% and manganese ≤1.70%, along with microalloying elements . This grade is designed for more demanding structural components in shipbuilding, offshore platforms, and heavily loaded marine structures requiring superior strength .

Both LR EH46 and LR EH55 are LR-certified extra-high-strength marine steels with excellent low-temperature toughness tested at -40°C, ensuring reliable performance in Arctic and harsh marine environments . Their primary difference lies in strength level: EH46 offers a minimum yield strength of 460 MPa with tensile strength of 570-720 MPa, suitable for general high-strength hull construction and offshore structures , while EH55 provides a higher minimum yield strength of 550 MPa with tensile strength reaching 670-830 MPa, designed for more demanding load-bearing applications requiring superior strength.

Chemical Composition

LR EH46 extra high Strength Chemical Composition
Grade	The Element Max (%)
Grade	C	Si	Mn	P	S	Al	N
LR EH46	0.20	0.55	1.70	0.030	0.030	0.015	0.020
	Nb	V	Ti	Cu	Cr	Ni	Mo
	0.02-0.05	0.03-0.10	0.02

LR EH55 extra high Strength Chemical Composition
Grade	The Element Max (%)
Grade	C	Si	Mn	P	S	Al	N
LR EH55	0.20	0.55	1.70	0.030	0.030	0.015	0.020
	Nb	V	Ti	Cu	Cr	Ni	Mo
	0.02-0.05	0.03-0.10	0.02

Mechanical Property

LR EH46 extra high strength property
Grade		Mechanical Property			Charpy V Impact Test
Grade	Thickness	Yield	Tensile	Elongation	Degree	Energy 1	Energy 2
LR EH46	mm	Min Mpa	Mpa	Min %	-40	J	J
	t≤50	460	570-720	19%		31	46
	50＜t≤70	460	570-720	19%		31	46
	70＜t≤100	460	570-720	19%		31	46
Note: Energy 1 is transverse impact test, Energy 2 is longitudinal

LR EH55 extra high strength property
Grade		Mechanical Property			Charpy V Impact Test
Grade	Thickness	Yield	Tensile	Elongation	Degree	Energy 1	Energy 2
LR EH55	mm	Min Mpa	Mpa	Min %	-40	J	J
	t≤50	550	670-830	18%		37	55
	50＜t≤70	550	670-830	18%		37	55
	70＜t≤100	550	670-830	18%		37	55
Note: Energy 1 is transverse impact test, Energy 2 is longitudinal