BS 2056:1991 download.Specification for Stainless steel wire for mechanical springs.
1 Scope
BS 2056 specifies the requirements for stainless steel wire, in diameters up to and including 10 mm, supplied in coils, on reels or in straight lengths, suitable for the manufacture of mechanical springs.
Specific requirements are given for six types of austenitic (301S26, 302S26, 316S33 and 316S42). including two types of low magnetic permeability (305S11 and 904S14), one type of martensitic (420S45) and one type of precipitation hardening (301S81) stainless steel spring wire. In addition to the definitive requirements, this standard also requires the items detailed in clause 2 to be documented. For compliance with this standard, both the definitive requirements and the documented items have to be satisfied.
NOTE I The titles of the publications referred to in this standard are listed on the inside back cover. NOTE 2 For the purposes of this British Standard the term “reel” is synonymous with the terms “spool” and “bobbin”.
2 Information and requirements to be agreed and to be documented
The following information to be supplied by the purchaser shall be fully documented.
Both the definitive requirements specified throughout the standard and the following documented items shall be satisfied before a claim of compliance with the standard can be made and verified:
a) the number of BS 2056,
i.e. BS 2056:
b) the steel type number (see Table 1);
c) the nominal diameter of the wire (in mm);
d)the tensile strength grade, if 301S26or 302S26 is being ordered (see Table 4);
e) the form of supply, i.e. coils, reels, or straight lengths;
1) any applicable requirements from the appropriate clauses for:
1) surface finish and condition of wire
(see clause 4);
2) packing and identification (see clauses 6
and 11);
g) any other special requirements.
3 Manufacture
3.1 Steelmaking process
The steel shall be made by an electric furnace process.
3.2 Chemical composition
The cast analysis shall comply with the composition ranges given in Table I for the appropriate steel type. On request, the wire manufacturer shall supply the cast analysis. Any subsequent analytical checks on the product shall take into consideration the heterogeneity normal to the steel and shall be in accordance with Appendix A.
3.3 Freedom from defects
3.3.1 The ingots, blooms or billets shall be so prepared as to remove surface imperfections that might produce defects in the wire made from them.
3.3.2 The rod from which the wire is drawn shall be free from harmful surface defects, pipe and other flaws (see also 4.1 for finished wire).
6 Method of supply
The wire shall be supplied in one of the following forms:
a) in coils;
b) on reels;
c) in straightened and cut lengths (only applicable to wire of 0.25 mm diameter and larger).
NOTE The tolerance on straightness of the cut lengths should be agreed between manufacturer and purchaser.
7 Sampling for mechanical tests
7.1 General
All tests shall be made on test pieces taken from the wire in the condition in which it is to be supplied to the purchaser. Apart from any straightening of the test lengths prior to testing, they shall not be treated in any way which may make them unrepresentative of the bulk of which they are a sample. Sampling shall be in accordance with 7.2, 7.3 or 7.4, as appropriate.
NOTE See clause 10 for retests.
7.2 Coils
A test piece shall be taken from each end of every coil. If small coils are split from parent coils, samples tested from either end of the parent coil will be considered representative providing the coils can be identified to the parent coil.
7.3 Reels
A test piece shall be taken from the free outside end of the wire on every reel.
7.4 Straight lengths
Wire supplied in straight lengths shall be grouped in a bundle or bundles clearly identified with the coil or coils from which the lengths were cut. Two test pieces shall be selected at random from the lengths as being representative of the product of that coil or wire.
8 Mechanical properties
8.1 Tensile strength
8.1.1 When supplied in coils or reels and tested in accordance with BS 4545, the tensile strength shall comply with the range appropriate to the type, grade and wire diameter given in Table 4, Table 5 or Table 6, or the maximum values in Table 7.
For material supplied in straight lengths, the stated values of tensile strength given
in Table 4, Table 5, Table 6 and Table 7 shall be reduced by up to 10 %.
8.1.2 After heat. treatment at 480 °C for 1 h. followed by cooling in air, the heat treated tensile strength of 301S81 wire shall be as given in Table 5.
8.1.3 Martensitic stainless steel wire type 420S45 shall be supplied in the softened or in the cold drawn condition to the tensile strength values given in Table 7.
8.2 Wrapping
The wrapping test shall be applied to all types of wire up to but not including 3 mm diameter in accordance with BS 4545. The wire shall not show sign of fracture when coiled eight complete turns around a mandrel of diameter equal to that of the wire (see clause 10).
8.3 Flexibility
A single U bend test shall he applied to wire of 3.00 mm and larger diameters.
When tested in accordance with BS 4545 and Appendix B the wire shall not show sign of failure (see clause 10).
To avoid the need for an excessive number of sizes of mandrel, the wire shall be deemed to have complied with this standard if it is bent around a mandrel smaller than that specified.
8.4 Wire cast
NOTE 1 Details of wire cast measurement are given in Appendix C.
8.4.1 Circular cast
When measured in accordance with C.2, wire from a reel shall take up a circular cast of diameter not less than barrel diameter of the reel and not more than 2.5 times the barrel diameter.
When measure in accordance with C.2. wire from a coil shall take up a circular cast of diameter not less than that of the original coil diameter and not more than 1.5 times the original coil diameter.
NOTE 2 For certain requirements. wire may be required to pay out approximately straight and in such circumstances the requirements for cast should be agreed between the manufacturer and the purchaser at the time of ordering.
8.4.2 Helix cast
When tested in accordance with C.3. the helix of a complete wap of wire, measured as the offset between the two ends of the wire, shall not exceed the values given in Table 8.
10.4 Straight lengths
For wire supplied in straight lengths, four additional test pieces shall be taken at random from the same bundle or bundles representing the product of the coil (see 7.4).
10.5 Results
If the additional test pieces pass all the tests, the appropriate coil, reel or bundles representing the product of the coil shall be deemed to comply with this standard. If any of them fail, the coil, reel or corresponding bundles shall be deemed not to comply with this standard.
11 Packing and marking
Consignments of wire shall be suitably protected against mechanical damage and corrosion during transport.
NOTE If special protection is required this should be agreed at the time of enquiry or order.
Wire in coils or bundles of lengths shall he securely tied.
All consignments shall carry a suitable label or labels on which the following shall be clearly shown:
a) the number and date of this British Standard,
i.e. BS 2O56:1991
b) the steel type number;
c) the nominal diameter of the wire (in mm);
d) tensile strength grade (for 301S26
and 302S26);
e) whether softened or cold drawn (for 420S45);
f) the manufacturer’s name;
g) any other information agreed between
manufacturer and purchaser.