Can Q235B low carbon steel replace LR grade A shipbuilding steel

Q235B low carbon steel is widely used in shipbuilding to replace LR grade A shipbuilding steel to save cost. So a lot of people regards those two materials as same. However, it is not that case. It is important to know differences  between Q235B low carbon steel and LR grade A shipbuilding steel so that you can make better choices and decisions.

First of all, let's check their chemical composition and mechanical properties.
Chemical composition of Q235B low carbon steel and LR grade A shipbuilding steel %:

GRADE	C	Mn	P	S	Si
LR grade A	≦0.21	≧2.5*C	≦0.035	≦0.035	≦0.50
Q235B	0.12-0.20	0.30-0.70	≦0.045	≦0.045	≦0.30

Mechanical properties of Q235B low carbon steel and LR grade A shipbuilding steel:

GRADE	YIELD STRENGTH	TENSILE STRENGTH	EXTENSION
	MPA	MPA	%
LR grade A	≧235	400~520	≧24
Q235B	≧235	375~460	≧26

Generally speaking, there is little difference in chemical composition and mechanical properties between Q235B low carbon steel and LR grade A shipbuilding steel.

This is why many customers can accept Q235B low carbon steel to replace LR grade A shipbuilding steel if they do not have strict classification requirements. In this case, Q235B steel has the advantages of fast delivery and low price.

But if users need a certificate of classification society, Q235B low carbon steel will no longer work. Only shipbuilding steel can get the certification with trackable Certificate number.