ISO 898-5:1998 pdf free download.Mechanical properties of fasteners made of carbon steel and alloy steel — Part 5: Set screws and similar threaded fasteners not under tensile stresses.
This part of ISO 898 specifies the mechanical properties of set screws and similar threaded fasteners not under tensile stresses with nominal thread diameters from 1.6 mm up to and including 24 mm. which are made of carbon steel or alloy steel.
The mechanical and physical properties apply when tested at an ambient temperature of 10 CC to 35 CC and will vary at higher or lower temperatures.
This pail of ISO 898 does not apply to set screws requiring special properties such as
— specified tensile stresses (see ISO 898-1);
— weldability:
— corrosion resistance:
— ability to withstand temperatures above 4- 300 CC or below —50 CC.
NOTE — Set screws made from free-cutting steel should not be used above + 250 CC.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this part of ISO 898 At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of ISO 898 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below, Members of IEC and ISO maintain registers of currently valid International Standards.
ISO 965-3:1998, ISO general purpose metric screw Threads —Tolerances — Part 3: Deviations for constructional Threads.
ISO 4948-1:1982. Steels — Classification — Part 1: Classification ol steels into unalloyed and alloy steels based on chemical composition.
ISO 6506:1981, Metallic materials — Hardness test — Brinell test.
ISO 6507-1:1997, Metallic materials — Vickers hardness test — Part 1: Test method.
1S06508:1986, Metallic materials— Hardness test— Rockwell test (scalesA – B-C- 0- E- F- G – H-K).
3 DesignaUon system
The property c’asses are designated by the symbols shown in table 1.
The numencal part of the symbol represents 1/10 of the minimum Vickers hardness.
The letter H in the symbo’ refers to hardness.
4 Materials
Set screws shall be made of steel conforming to the requirements specified in table 2.
For property class 45H, other materials may be used provided that the proof torque requirements in 6.3 are met.
6.2.2 Measurement methods
6.2.2.1 Microscopic method
This method allows the determination of both E and G.
The specimens to be used are longitudinal sections taken through the thread axis approximately half a nominal diameter from the end of the screw, after a heat treatment operations have been performed on ttie product. The specimen shall be mounted for gnnding and polishing in a clamp or plastic mount, the latter being the preferred method.
After mounting, grind and polish the surface in accordance with good metallographic practice.
Etching in a 3 % nital (concentrated nitric acid in ethanol) solution is usually suitable for showing changes in microstructure caused by decarbunzation,
Unless otherwise agreed between the interested parties a 100 x magnification shall be used for examination.
If the microscope is of a type with a ground glass screen, the extent of decartxirization can be measured directly with a
scale. If an eyepiece is used for measurement, it should be of an appropriate type, containing a cross-hair or a scale.
6.2.2.2 Hardness method (referee method for partial decarburization and carburization)
The decarburization test by the hardness measurement method is applicable only for threads with pitches, P. of 1,25 mm and larger, except for property class 45H, wtiere it is applicable for all sizes.
The hardness measurements are made at three points in accordance with figure 2. Values for E are given in table 4. The load shall be 300 g.
Hardness determination for point 3 shall be made on the pitch line of the thread adjacent to the thread on which determinations at points 1 and 2 are made.
The Vickers hardness value at point 2 (HV2) shall be equal to or greater than that at point 1 (HV1) minus 30 Vickers units. In this case the height of the non-decarburized zone E is at least as specified in table 4.
The Vickers hardness value at point 3 (HV3) shall be equal to or less than that at point 1 (HV1) plus 30 Vickers units. An increase of more than 30 Vickers units indicates that carburization is not permissible.
Complete decarburization up to the maximum specified in table 3 cannot be detected by the hardness measurement method
NOTE — Careful differentiation should be made between an increase in hardness caused by carbuiizahon and that due to heat treatment or cold working of the surface.
6.3 Proof torque test for hexagon socket set screws of property class 45H
Hexagon socket set screws class 45H shall conform to the Proof torque requirements given in table 5.
Key
1 Torque wrench
2 Set screw under test
3 Test block: hardness min 50 HRC, tolerance class of the internal thread 5H (see ISO 965-3)
4 Backing screw: hardness 450 HV to 570 HV
Figure 3— Torque test fixture
Using a hexagon test bit with a tolerance class of h9 for the widths across flats. s, with a minimum width across corners 1,13 ‘min and a hardness of 55 HRC to 60 HRC. engaging the fuM depth of the set screw socket, the screw shall withstand the proof torque given in table 5 without splitting or cracking.
For this proof torque test, a calibrated torque measuring instrument shall be used.
Visual marks at the socket due to torque testing shall not be cause for rejection.
7 Marking
7.1 MarkIng of set screws with the property class
Marking of set screws with property classes as described in clause 3 is not generally required. If in special cases marking is
agreed between the interested parties the symbol of the property class should be used as the marking symbol.
7.2 Trade marking
The manufacturer’s identification marking is not required.