Section 3 Castings for machinery construction
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules for the Manufacture, Testing and Certification of Materials, July 2022 - Chapter 4 Steel Castings - Section 3 Castings for machinery construction

Section 3 Castings for machinery construction

3.1 Scope

3.1.1 This Section gives the material requirements for carbon, carbon-manganese and alloy steel castings intended for machinery construction and which are not within the scope of Ch 4, 4 Castings for crankshafts to Ch 4, 7 Ferritic steel castings for low temperature service.

3.1.2 Where it is proposed to use steels of higher carbon content than is indicated in Table 4.3.1 Chemical composition limits for machinery steel castings (%): C, C-Mn steels or Table 4.3.2 Chemical composition limits for machinery steel castings (%): Alloy steels, particulars of the chemical composition, mechanical properties and heat treatment are to be submitted for approval.

3.1.3 The manufacture or repair of cast steel connecting rods is not permitted, except where the manufacturing and quality control procedures have been approved by LR. For approval purposes, tests are to be carried out at the place of manufacture using the proposed process to demonstrate that the castings are sound. Tests are to be carried out to confirm that the appropriate mechanical properties are attained within the casting, including areas where weld repairs have been performed. Any changes to manufacturing, repair and quality control procedures are to be submitted to LR for approval, see also Ch 1, 2.2 LR Approval – General.

3.2 Chemical composition

3.2.1 The chemical composition of ladle samples for carbon and carbon-manganese machinery steel castings is to comply with the limits given in Table 4.3.1 Chemical composition limits for machinery steel castings (%): C, C-Mn steels, or where applicable, the requirements of the approved specification.

Table 4.3.1 Chemical composition limits for machinery steel castings (%): C, C-Mn steels

Steel type Applications C (max.) Si (max.) Mn S (max.) P (max.) Residual elements (max.) Total residuals (max.)
Cu Cr Ni Mo
C, C-Mn Castings for non-welded construction 0,40 0,60 0,50-1,60 0,035 0,035 0,30 0,30 0,40 0,15 0,80
Castings for welded construction 0,23 (See Note) 0,60 0,50-1,60 0,035 0,035 0,30 0,30 0,40 0,15 0,80
Note Castings which are intended for parts of a welded fabrication are to be of weldable quality with a carbon content generally not exceeding 0,23%. The carbon content may be increased above this level provided that the carbon equivalent (Ceq) is not more than 0,41%, calculated using the following formula:

3.2.2 Proposals to use steels with higher carbon content, or alloy steels, for welded construction will be subject to special consideration.

3.2.3 For alloy machinery steel castings, the chemical composition of the ladle samples is to comply with the limits provided in Table 4.3.2 Chemical composition limits for machinery steel castings (%): Alloy steels, or where applicable, the requirements of the approved specification.

Table 4.3.2 Chemical composition limits for machinery steel castings (%): Alloy steels

Steel type Applications C (max.) Si (max.) Mn S (max.) P (max.) Alloying elements (min.) (See Note)
Cu Cr Ni Mo
Alloy Castings for non-welded construction 0,45 0,60 0,50-1,60 0,030 0,035 0,30 0,40 0,40 0,15
Castings for welded construction Alloying element values are to comply with recognised national/ international standards or designer’s specifications and shall be agreed with LR.
Note. At least one of the elements shall comply with the minimum content.

3.3 Heat treatment

3.3.1 Castings are to be supplied in one of the following delivery conditions:

  1. Carbon and carbon-manganese steels:
    • Fully annealed
    • Normalised
    • Normalised and tempered
    • Quenched and tempered.
  2. Alloy steels:
    • Normalised
    • Normalised and tempered
    • Quenched and tempered.

    For all types of steel, the tempering temperature is to be not less than 550°C.

3.3.2 The delivery condition shall meet the design and application requirements. It is the manufacturer’s responsibility to select the appropriate heat treatment method for obtaining the required mechanical properties.

3.3.3 Engine bedplate castings, turbine castings and any other castings where dimensional stability and freedom from internal stresses are important, are to be given a stress relief heat treatment. This is to be at a temperature not lower than 550°C, followed by furnace cooling to 300°C or lower. Alternatively, full annealing may be used provided that the castings are furnace cooled to 300°C or lower.

3.4 Mechanical tests

3.4.1 At least one tensile test specimen and one set of impact tests are to be taken from material representing each casting or batch of castings.

3.4.2 Where the casting is of complex design, or where the finished mass exceeds 10 tonnes, two cast on test samples are to be provided from the heaviest section, located as far as practicable from each other. Where large castings are made from two or more casts which are not mixed in a ladle prior to pouring, two or more test samples are required corresponding to the number of casts involved. The test samples are to be integrally cast at locations as widely separated as possible.

3.4.3 Table 4.3.3 Mechanical properties for machinery steel castings intended for welding and Table 4.3.4 Mechanical properties for machinery steel castings not intended for welding gives the minimum requirements for yield stress, elongation, reduction of area and impact test energy values corresponding to steel types and different strength levels, but it is not intended that these should necessarily be regarded as specific grades. Intermediate levels of minimum tensile strength may be specified, in which case minimum values for yield stress, elongation and reduction of area may be obtained by interpolation.

Table 4.3.3 Mechanical properties for machinery steel castings intended for welding

Steel type Specified minimum tensile strength (N/mm2) Yield stress (N/mm2) min. Elongation on 5, 65 min.

Reduction of area (%) min.

Charpy V-notch impact test (See Note)
Test temperature (°C) Minimum average energy (J)

C, C-Mn

400-550

440-590

480-630

520-670

560-710

600-750

200

220

240

260

300

320

25

22

20

18

15

13

40

30

27

25

20

20

0

27

Alloy

550-700 355 18 30
600-750 400 16 30
650-800 450 14 30
700-850 540 12 28
Note. Special consideration may be given to alternative requirements for Charpy V-notch impact test, depending on design and application, and subject to agreement by LR.

Table 4.3.4 Mechanical properties for machinery steel castings not intended for welding

Steel type

Specified minimum tensile strength (N/mm2) Yield stress (N/mm2) min. Elongation on 5, 65 min. Reduction of area (%) min. Charpy V-notch impact test (See Note 1)
Test temperature (°C) Minimum average energy (J)

C, C-Mn

400-550

440-590

480-630

520-670

560-710

600-750

200

220

240

260

300

320

25

22

20

18

15

13

40

30

27

25

20

20

AT

(See Note 2)

27

Alloy

550-700 340 16 35
600-750 400 16 35
650-800 450 14 32
700-850 540 12 28
Note 1. Special consideration may be given to alternative requirements for Charpy V-notch impact test, depending on design and application, and subject to agreement by LR.
Note 2. AT refers to Ambient Temperature (i.e. 23°C±5°C), which is specified in ISO 148-1.

3.4.4 Castings may be supplied to any specified minimum tensile strength selected within the general limits detailed in Table 4.3.3 Mechanical properties for machinery steel castings intended for welding and Table 4.3.4 Mechanical properties for machinery steel castings not intended for welding respectively, but are subject to any additional requirements of the relevant construction rules.

3.4.5 The results of all mechanical tests are to comply with the requirements of Table 4.3.3 Mechanical properties for machinery steel castings intended for welding and Table 4.3.4 Mechanical properties for machinery steel castings not intended for welding respectively, appropriate to the specified minimum tensile strength or, where applicable, the requirements of the approved specification.

3.4.6 For alloy steel castings and carbon-manganese steel castings containing more than 0,40 per cent carbon, the results of all mechanical tests are to comply with an approved specification.

3.4.7 When a casting, or a batch of castings, has failed to meet the mechanical test requirements, it may be re-heat treated and re-submitted for acceptance tests but this may not be carried out more than twice, see Ch 2, 1.4 Re-testing procedures. The additional tests detailed in Ch 2, 1.4 Re-testing procedures are to be taken, preferably from the same test sample, but alternatively from another test sample representative of the casting or batch of castings.

3.5 Non-Destructive Examination

3.5.1 All piston crowns and cylinder heads are to be examined by ultrasonic testing unless otherwise agreed with LR. Piston crowns intended for engines having a bore size larger than 400 mm and cylinder heads intended for engines having a bore size larger than 300 mm are additionally to be examined by magnetic particle or penetrant testing in accordance with and Ch 4, 1.8 Volumetric Non-Destructive Examination.

3.5.2 Engine bedplate and transverse girder castings are to be examined by ultrasonic and magnetic particle or penetrant testing in accordance with Ch 4, 1.7 Visual and surface Non-Destructive Examination 1.7.9 and Ch 4, 1.8 Volumetric Non-Destructive Examination.

3.5.3 Turbine castings are to be examined by magnetic particle or dye penetrant testing in accordance with Ch 4, 1.7 Visual and surface Non-Destructive Examination . In addition, an ultrasonic or radiographic examination is to be made in way of fabrication weld preparations.

3.5.4 Other castings are to be examined by non-destructive methods where specified.


Copyright 2022 Clasifications Register Group Limited, International Maritime Organization, International Labour Organization or Maritime and Coastguard Agency. All rights reserved. Clasifications Register Group Limited, its affiliates and subsidiaries and their respective officers, employees or agents are, individually and collectively, referred to in this clause as 'Clasifications Register'. Clasifications Register assumes no responsibility and shall not be liable to any person for any loss, damage or expense caused by reliance on the information or advice in this document or howsoever provided, unless that person has signed a contract with the relevant Clasifications Register entity for the provision of this information or advice and in that case any responsibility or liability is exclusively on the terms and conditions set out in that contract.