SIST EN 3684:2009

SIST EN 3684:2009 is the Slovenian standard identical to EN 3684:2007, published by SIST. It specifies a metallographic test method for determining the β transus temperature of titanium alloy wrought products for aerospace applications. In practice, it tells laboratories how to heat-treat a set of specimens and use primary α content to locate the transition range.

What does SIST EN 3684:2009 specify?

SIST EN 3684:2009 specifies one test method for titanium alloy wrought products used in aerospace applications. The method is organized as a short procedure standard with clauses for scope, normative references, terms and definitions, principle, procedure, and test report.

The document ties the method to EN 3114-001 and EN 3683. That matters because the actual specimen preparation, terminology, and microscopic evaluation rely on those companion standards.

What are the key requirements of SIST EN 3684:2009?

SIST EN 3684:2009 determines β transus temperature by checking primary α content in several test samples heat treated at different temperatures around the assumed transition point. The temperature range is identified between the first temperature where primary α is 0 % and the next lower temperature where primary α is greater than 0 %.

• Clause 4 - principle: The method uses primary α content as the indicator for the β transus temperature. In practice, the reader must run more than one heat-treatment temperature and compare the microstructures, not rely on a single specimen.

• Clause 5.1 - sampling: The sample material should be as homogeneous as possible and have a fine distribution of α and β phases. If needed, additional deformation may be applied, for example by upsetting in the (α + β) range. This helps obtain a material state suitable for consistent metallographic assessment.

• Clause 5.2 - test pieces: Test pieces are preferably cylindrical, about 10 mm in diameter and 10 mm long, or a 10 mm cube. The section to be examined should preferably be transverse. In practice, the specimen size and cut direction are chosen to make the microstructural comparison representative.

• Clause 5.3 - heat treatment: The temperatures are selected around the assumed β transus temperature, and three temperatures at 10 °C intervals are normally sufficient for routine work. Each test piece is heated at the specified temperature ± 5 °C for 15 min to 30 min, then immediately water quenched. Optional annealing may be used to improve contrast during inspection.

• Clause 5.4 - metallographic examination: The test pieces are cut in half, and the sections are prepared and examined according to EN 3683. This means the actual α-content assessment is not free-form; it must follow the companion method.

• Clause 5.5 - expression of results: The result is recorded as a temperature range bounded by the temperature where primary α is 0 % and the next lower temperature where primary α is greater than 0 %. The standard also allows a single extrapolated value from the primary α content versus temperature diagram. For practice, this gives either a conservative range or a derived point value.

• Clause 6 - test report: The report must identify the product, sample location, piece dimensions, heat-treatment temperatures, any annealing, the EN 3683 results, equipment used, test date, traceability to the people who performed the work, and any deviations. This is the record a buyer, quality manager, or auditor would check.

What terms does SIST EN 3684:2009 define?

SIST EN 3684:2009 uses terms and definitions from EN 3114-001, and its procedure centers on a few key expressions.

• β transus temperature - the transition temperature that is identified from the change in primary α content after heat treatment at different temperatures.
• Primary α content - the amount of primary α used to decide whether a specimen is above or below the β transus temperature.
• (α + β) range - the temperature region mentioned for optional deformation before testing, where both phases are present.
• Test piece - the individual specimen prepared for heat treatment and metallographic examination.
• Transverse section - the preferred cut surface for examination because it gives a representative view of the product.
• Quenched - cooled immediately in water after heat treatment to preserve the relevant microstructure for examination.

Who uses SIST EN 3684:2009?

SIST EN 3684:2009 is used by aerospace materials laboratories, metallography labs, and quality assurance teams that test titanium alloy wrought products. It is also relevant to manufacturers, suppliers, and buyers who need a defined method for product qualification, inspection, or dispute resolution.

In practice, users apply it to select heat-treatment temperatures, prepare specimens, determine primary α content, and document the β transus temperature for acceptance or process control.

What changed in SIST EN 3684:2009 from the previous edition?

SIST EN 3684:2009 identifies EN 3684:2007 as the European Standard it adopts. The document text provided here presents the EN 3684:2007 method as the basis of the Slovenian standard.

Which standards are used with SIST EN 3684:2009?

• EN 3114-001 - provides the general requirements for microstructure examination of (α + β) titanium alloy wrought products and supplies the terms and definitions used here.
• EN 3683 - provides the method for determining primary α content by point count and line intercept method, which this standard uses for the metallographic assessment.

What does the SIST EN 3684:2009 document contain?

SIST EN 3684:2009 is a procedural test-method standard. It gives the sampling approach, preferred test-piece shapes and sizes, heating and quenching conditions, the metallographic preparation route, and the rule for turning primary α measurements into a β transus temperature result.

It also sets out what the test report must include, so the result can be traced back to the product, specimen, equipment, and operators. The document is therefore used for laboratory testing, product qualification, and quality records.