Part II - Material Specifications and Testing Requirements

4 Material specification

4.1 The material specification should be submitted to the Administration for approval. The test requirements and acceptance criteria for the material are described in detail in the appendix.

4.2 The steel should be fully killed and fine-grained. The condition of supply for all material should be hot rolled with subsequent controlled cooling as necessary. The reduction ratio of slab to finished product thickness should not be less than 3:1. Other conditions of supply should be in accordance with those prescribed by the Administration.

4.3 The use of high manganese austenitic steel is limited to steel plates with a thickness between 6 mm and 40 mm. For thicknesses greater than 40 mm, special consideration may be given by the Administration. Other dimensions may be subject to acceptance by the Administration.

5 Chemical composition

The chemical composition for high manganese austenitic steel should meet the requirements of recognized standards, such as ASTM standard A1106/A1106M-17 as shown in table 1, or ISO 21635:2018.

Table 1: Chemical composition for high manganese austenitic steel

(Ref. ASTM standard A1106/A1106M-17)

	Chemical Composition (wt.%, product)
	C	Si	Mn	P	S	Cr	Cu	B	N
Requirements	0.35 - 0.55	0.10 - 0.50	22.50 - 25.50	Max. 0.030	Max. 0.010	3.00 - 4.00	0.30 - 0.70	Max. 0.005	Max. 0.050

Note: Silicon (Si) may be less than 0.10 %, provided total aluminium is 0.03 % or higher, or provided acid soluble aluminium is 0.025 % or higher.

6 Mechanical properties

Mechanical properties for the base metal of high manganese austenitic steel should meet the requirements of the IGC and IGF Codes, as relevant, and also recognized standards applied to chemical composition, such as ISO 21635:2018 (refer to table 2 below) or ASTM A1106/A1106M-17. Compliance should also be documented in accordance with material testing requirements and acceptance criteria outlined in the appendix.

.1 Base metal

Table 2: Mechanical properties for base metal of high manganese austenitic steel

(Reference ISO 21635:2018)

Minimum yield strength (0.2 % offset) N/mm²	Tensile strength N/mm²	Minimum elongation % at 5.65√S₀
400	800 to 970	22.0

(Note the impact test requirements as specified in table 6.3 of the IGC Code or table 7.3 of the IGF Code, as relevant)

.2 As welded condition

Table 3: Typical mechanical properties for "As welded condition"

Tensile properties
Minimum yield strength (0.2 % offset) N/mm²	Minimum tensile strength N/mm²	Minimum elongation % at 5.65√S₀
400	660	22.0

(Note the impact test requirements as specified in table 6.3 of the IGC Code or table 7.3 of the IGF Code, as relevant)

7 Welding of metallic materials and non-destructive testing

Welding of metallic materials and non-destructive testing should be in accordance with chapter 6 of the IGC Code or chapter 16 of the IGF Code. See "Material testing requirements and test acceptance criteria" as set out in the appendix. Typical minimum values of yield and tensile strength for welded conditions are shown in table 3.

8 Material testing and acceptance criteria

The material testing and applied acceptance criteria should be in accordance with chapter 6 of the IGC Code or chapter 16 of the IGF Code and the appendix. Compliance should also be documented in accordance with the material testing requirements and acceptance criteria outlined in the appendix.

9 Manufacturer approval scheme

Approval of the manufacturer should be carried out in accordance with section 6.2.2 of the IGC Code or section 16.1.1 of the IGF Code and to the satisfaction of the Administration.