GB/T 24814-2023 Round steel short link chains for lifting purposes - Medium tolerance sling chains - Grade 4,stainless steel
1 Scope
This document specifies the requirements for medium tolerance sling chains of grade 4 from stainless steel for use preferably in chain slings of grade 4 from stainless steel or for other lifting purposes.
The range of nominal diameter, dn , covered by this document is from 4 mm to 22 mm.
These sling chains are round steel short link chains with a nominal pitch, pn = 3 × dn, electrically welded, solution-annealed and tested. They are for use in the temperature range - 100 °C to + 400 °C. They comply with the general conditions of acceptance of ISO 1834.
NOTE 1: Because sling chains are solution-annealed in the finished condition, they can be used without restrictions with regard to the corrosion resistance of the steels according to 5.2. Higher grades of stainless steel chains are achieved by cold drawing of the wire prior to the chain manufacturing. Therefore, solution annealing is not possible without reduction of strength. The weld seam, in particular, represents a critical area with regard to the corrosion resistance.
NOTE 2: Resistance butt welding and flash welding are listed in ISO 4063.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 1834 Short link chain for lifting purposes - General conditions of acceptance
Note: GB/T 20946-2007, Short link chain for lifting purposes - General conditions of acceptance (ISO 1834-1:1999, IDT)
ISO 7500-1 Metallic materials - Calibration and verification of static uniaxial testing machines - Part 1: Tension/compression testing machines - Calibration and verification of the force-measuring system
Note: GB/T 16825.1-2022, Metallic materials - Calibration and verification of static uniaxial testing machines - Part 1: Tension/compression testing machines - Calibration and verification of the force-measuring system (ISO 7500-1:2018, IDT)
ISO 13385-1 Geometrical product specifications (GPS) - Dimensional measuring equipment - Part 1: Design and metrological characteristics of Callipers
ISO 16143-2 Stainless steels for general purposes - Part 2: Corrosion-resistant semi-finished products, bars, rods and sections
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1834 apply.
4 Dimensions, masses and designation
4.1 Dimensions and masses
The bases for calculation of the values for the dimensions listed in Table 1 are given in Annex A.
The bases for calculation of the values for the mass per metre listed in Table B.1 are given in Annex B.
The nominal diameter, dn , of the sling chain corresponds to the nominal diameter of the steel wire as presented in ISO 16124, or bar as presented in ISO 1035-1, from which the sling chain is made.
Preferred nominal diameters are given in Table 1, column 1. Other nominal diameters may be used, provided the corresponding dimensions and tolerances are calculated in accordance with Annex A.
4.2 Designation
Figure 3 shows the general format for a designation to be used.
5 Requirements
5.1 General
The sling chain shall comply with the requirements of ISO 1834 as well as those of this document.
5.2 Material
The steel used shall be austenitic stainless steels with molybdenum and shall be resistant against intergranular corrosion, for example the steel with the ISO name X6CrNiMoTi17-12-2 and the ISO number 4571-316-I according to ISO 15510.
After solution annealing intergranular corrosion is unlikely at a service temperature of +400 °C and with an extra low carbon content of the steel. To avoid this corrosive attack under severe service conditions and with higher carbon contents of the steel, a stabilization with titanium is recommended.
