An in-depth analysis of the key differences between ABS Grade E and Grade A

I. Fundamental Difference: Impact Resistance at Low Temperatures

Judging by the mechanical properties tables, the values for Grade A and Grade E are essentially identical. However, the low-temperature impact requirement at –40°C places Grade E in a completely different technical category.

II. Significant Differences in Chemical Composition

To achieve the required toughness at –40°C, Grade E requires much stricter control over its chemical composition:

Chemical Composition (Heat Analysis, wt %)

Grade A does not have strict requirements regarding grain refinement and may be produced using the boiling steel process.

Grade E must utilise fully killed steel and control grain size through aluminium treatment, thereby achieving fine ferritic grains in the hot-rolled or TMCP (Thermomechanical Control of Processing and Cooling) condition.

III. Differences in Delivery Conditions

Grade A: Typically supplied in the hot-rolled condition, requiring no special heat treatment.

Grade E: Typically requires delivery in a normalised or TMCP condition to ensure uniformity of core properties.

IV. Engineering Implications

Selecting Grade E entails a certain sacrifice in cost-effectiveness (costs are 15%–25% higher) in exchange for the following critical assurances:

Safety of the vessel when operating on polar routes or in the North Atlantic during winter

Resistance to brittle fracture in outer plating and side structures

Compliance with classification society requirements for special inspections of critical structural components

V. Engineering Recommendations

Grade A must not be used as a substitute for Grade E in side plating intended for low-temperature environments.

Although short-term mechanical performance tests may indicate compliance, the risk of brittle fracture will increase significantly under the low-temperature impact conditions corresponding to the design service conditions.