ISO 683-5:2017

Overview

ISO 683-5:2017 specifies the technical delivery requirements for nitriding steels - a subset of heat-treatable and alloy steels designed for nitriding to improve surface hardness, wear resistance and fatigue life. The standard applies to a range of product forms including semi‑finished products (blooms, billets, slabs), bars, wire rod, hot‑rolled plates/wide flats, and hammer or drop forgings manufactured from the steel grades listed in Table 3 and supplied in the heat‑treatment and surface conditions referenced in Tables 1 and 2. These steels are generally intended for fabrication of quenched and tempered parts that are subsequently nitrided. Mechanical property requirements are limited to the sizes given in Table 6.

Key Topics and Requirements

• Scope of delivery: Defines product forms covered (semi‑finished, bars, wire rod, plates, forgings) and normal/particular heat‑treatment and surface conditions.
• Steel classification and designation: Grades follow ISO 4948 series and are classified as alloy special steels.
• Technical delivery requirements (Clause 7): Chemical composition, hardness, mechanical properties, machinability, cold shearability, grain size, non‑metallic inclusions, internal soundness, surface quality and decarburization.
• Ruling section concept: Mechanical properties apply to a defined equivalent round bar diameter (ruling section).
• Inspection and testing (Clauses 8–9): Specifies inspection documents, testing frequency and accepted test methods for chemical analysis, hardness, tensile and impact testing.
• Ordering and customization: Purchaser must supply mandatory information; special or supplementary requirements can be agreed at enquiry/order (see Clause 5.2 and Annex B).
• Traceability and marking: Requirements for cast traceability and product marking are included.

Practical Applications and Users

Who uses ISO 683-5:2017

• Steel manufacturers and mills producing nitriding grades
• Heat‑treat and nitriding service providers
• Design and manufacturing engineers specifying nitrided machine parts (gears, shafts, cams, fasteners)
• Quality, inspection and procurement teams enforcing delivery requirements
• OEMs in automotive, industrial machinery and other sectors where surface hardness and fatigue resistance are critical

Practical value

• Ensures consistent material quality and repeatable nitriding performance
• Provides clear acceptance criteria for chemical, mechanical and surface properties
• Reduces ambiguity in procurement contracts and inspection procedures

Related Standards

Key normative references incorporated by ISO 683-5:2017 include:

• ISO 404 (General technical delivery requirements for steel)
• ISO 148-1 (Charpy impact test)
• ISO 377 (Sampling and preparation of test pieces)
• ISO 643 (Grain size)
• ISO 7788, ISO 9443, ISO 10474, ISO 14284 (surface finish, quality classes, inspection documents, sampling)

ISO 683-5:2017 is a practical specification for anyone sourcing, producing or inspecting steels intended for nitriding and nitrided components.