Page 425 - Marine Structural Design

Part I11

Fatigue and Fracture

Chapter 22 Material Selections and Damage Tolerance Criteria

22.1 Introduction
Engineering applications of the fatigue and fracture technologies will be discussed in this
Chapter, including:
Material Selections and Fracture Prevention
Weld Improvement and Repair
Damage Assessment and Damage Tolerance Criteria
Non-Destructive Inspection

22.2 Material Selections and Fracture Prevention

22.2.1 Material Selection
Tensile strength is the key mechanical properties for strength design of structures. The
materials used are required to have satisfactory weldability and fracture toughness that is
satisfactory for the intended application environment (temperature). Fatigue and corrosion
characteristics are also important material properties. In the design codes, requirements for
materials and welding are defined for the construction of the hull and machinery, see e.g. ABS
(2002). The material requirements in Rules are defined for mild steel, higher strength steel and
low temperature materials, including:
process of manufacture
chemical composition
condition of supply
tensile properties
impact properties
marking
surface finish
To certificate compliance with the above material requirements, the test specimens and
number of tests are defined by the Rules along with the requirements for approval of welding
procedures and qualification of welders.