1、 ENGINEERING MATERIAL SPECIFICATION Material Name Specification Number Date Action Revisions 2002 09 26 Revised Updated and renumbered 1989 02 28 B/031521TC Minor changes, release box changed 1989 01 09 SM/ER1995TC Released B.Edwards, EAO C.A.McKenney E.Staff Printed copies are uncontrolled Page 1 o
2、f 3 Copyright 2002, Ford Global Technologies, Inc. STEEL, SCREWS AND BOLTS SURFACE HARDENED WSD-M1A284-B 1000 N/mm2 TENSILE STRENGTH 1. SCOPE The material defined by this specification is a heat treated steel with controlled surface hardness. 2. APPLICATION This specification was released originally
3、 for material used for screws and bolts with trilobular prevailing torque features. 3. REQUIREMENTS 3.1 STANDARD REQUIREMENTS FOR PRODUCTION MATERIALS Material suppliers and part producers must conform to the Companys Standard Requirements For Production Materials (WSS-M99P1111-A). 3.2 MATERIAL The
4、choice of steel is at the manufacturers discretion and shall be suitable to meet the specified hardenability and other properties. The general quality of manufacture of the steel and wire product for bolt making shall conform to the relevant national standard for the country of sourcing. In the abse
5、nce of a national standard or for referee purposes, the steel shall conform to ISO 4954, section 1. Specific requirements for composition, hardenability, mechanical properties and treatment condition of the wire shall conform to ISO 4954 or the relevant national or industry standard. 3.3 HEAT TREATM
6、ENT 3.3.1 CORE HARDNESS, HV30 320 - 380 The core hardness shall be determined at the mid radial position on a cross section taken 1d from the threaded end. 3.3.2 SURFACE HARDNESS, HV 320 - 460 The surface hardness shall be determined at any suitable position on the bolt, but no more than 0.02mm of s
7、urface shall be removed during preparation of a suitable surface for the hardness test. ENGINEERING MATERIAL SPECIFICATION WSD-M1A284-B Page 2 of 3 Copyright 2002, Ford Global Technologies, Inc. 3.3.3 CASE DEPTH, mm, max 0.1 Case depth shall be determined for referee purposes by microhardness traver
8、se by the HV 0.3 method. The case depth is that depth with a hardness of 30 Vickers points above the actual core hardness. The bolts shall contain no decarburisation; the surface hardness shall not be less than the actual core hardness determined by the same hardness test method. 3.4 BREAKING FORCE,
9、 kN min (ISO 898/1 Clause 8.5 except 4 degree wedge angle) Size M5 X 0.8 13 M6 X 1.0 19 M8 X 1.25 34 M10 X 1.5 55 M12 X 1.75 80 The “Trilobular“ requirement applies to bolts with stress areas less than the standard ISO Metric. Fracture shall occur in the threaded area, except for bolts and screws wi
10、th special heads which are weaker than the threaded section. The above requirements apply to head diameters up to 1.7d. For products with head diameter above 1.7d the head may be machined to 1.7d prior to test. For products too short for tensile testing a 4 degree, head soundness test will apply. Te
11、st in accordance with ISO 898/1 clause 8.7. 3.5 PROTECTIVE FINISH The protective finish shall be of a non embrittling type and shall be as released or as specified on the Engineering drawing for the part. 3.6 DEFECTS The general quality of thread, occurence and severity of thread defects shall confo
12、rm to the requirements of the Worldwide Standard Parts Manual, WA990. Malformations or laps formed at crests of serations shall be no deeper than 75 % of serration height. No more than two serrations shall be deformed to this extent. ENGINEERING MATERIAL SPECIFICATION WSD-M1A284-B Page 3 of 3 Copyri
13、ght 2002, Ford Global Technologies, Inc. 4. GENERAL INFORMATION The information given below is provided for clarification and assistance in meeting the requirements of the specification. This material has a core hardness in line with ISO 898/1 property class 10.9. Products manufactured to this specification will give mechanical properties similar to grade 10.9. However, the potentially high surface hardness may lead to a reduction in product ductility.
