Overview
LR AH32 is a higher-strength structural steel plate certified by Lloyd's Register for shipbuilding and marine applications, impact tested at 0 degrees C for general marine environments. LR AH69 is an ultra-high-strength marine steel plate also certified by LR, impact tested at 0 degrees C, designed for the most demanding load-bearing applications requiring maximum strength-to-weight ratio.
Mechanical Properties
LR AH32 has a minimum yield strength of 315 MPa, tensile strength of 440 to 590 MPa, and minimum elongation of 22 percent, with impact energy of 20 J transverse and 31 J longitudinal at 0 degrees C. LR AH69 has a minimum yield strength of 690 MPa, tensile strength of 770 to 940 MPa, and minimum elongation of 16 percent, with impact energy of 46 J transverse and 69 J longitudinal at 0 degrees C.
Chemical Composition
AH32 limits carbon to 0.18 percent and manganese to 0.90 to 1.60 percent with copper, chromium, nickel, and molybdenum microalloying. AH69 limits carbon to 0.21 percent and manganese to 1.70 percent, with microalloying elements such as nickel, chromium, molybdenum, vanadium, and titanium to achieve higher strength while maintaining weldability, requiring advanced processing such as quenching and tempering.
Applications
AH32 is widely used for hull structures and general shipbuilding components. AH69 is designed for the most demanding load-bearing applications in shipbuilding and offshore platforms requiring maximum strength-to-weight ratio.
Selection Guidance
Choose AH32 for general high-strength hull construction at economical cost. Choose AH69 where the design requires the highest strength with minimum plate thickness, accepting the more complex alloying and processing.
Frequently Asked Questions
Q: What is the yield strength of LR AH32?
A: 315 MPa minimum, with tensile strength of 440 to 590 MPa.
Q: What is the yield strength of LR AH69?
A: 690 MPa minimum, with tensile strength of 770 to 940 MPa.
Q: What impact temperature applies?
A: 0 degrees C for both grades.
Q: What is the elongation of AH69?
A: 16 percent minimum, versus 22 percent for AH32.
Q: Where is AH69 used?
A: In the most demanding load-bearing shipbuilding and offshore applications.
Q: How is AH69's strength achieved?
A: Through nickel, chromium, molybdenum, vanadium, and titanium alloying with quenching and tempering.
For LR AH32 and AH69 certified marine steel plate quotations, contact our sales team.
