Overview - ISO 4215:2022 (thermogravimetry for high‑temperature corrosion testing)
ISO 4215:2022 specifies a thermogravimetric (TG) test method for continuous, high‑temperature corrosion testing of metallic materials under isothermal or thermal‑cycling conditions. The standard defines how to measure and record mass change of metals and alloys as a function of time and temperature using a thermobalance, enabling discrimination between mass gain (oxidation) and mass loss (volatilization or spalling).
Keywords: ISO 4215:2022, thermogravimetry, high‑temperature corrosion testing, thermobalance, TG curve, isothermal, cyclic
Key technical topics and requirements
- Test principle: Continuous mass monitoring of a suspended test piece during controlled heating, dwell and cooling cycles; output is a TG curve (mass change per unit surface area vs time).
- Modes: Isothermal exposure (constant HT temperature) and cyclic exposure (defined cold/hot dwells and controlled heating/cooling).
- Heating/cooling rates: Minimum controlled heating and cooling rates of 60 °C/min (deviations must be reported).
- Test atmosphere: Inert, oxidizing, reducing or corrosive gases (dry or humid); atmosphere may be established before heating except where inert heating is allowed.
- Test pieces and preparation:
- Accepts various geometries (sheets, discs, rods); size must be smaller than furnace diameter.
- Final surface finish produced with abrasives of mean particle diameter ≈ 15 µm (regional abrasive standards listed).
- Dimensional measurement precision ±0.02 mm at minimum three positions.
- Samples suspended by wire/rod/cradle; holders must not block gas access or retain spalled material.
- Equipment & calibration: Requirements for thermobalance, furnace, temperature probe, data acquisition, gas flow and buoyancy consideration. Mass and thermocouple calibrations are mandated (referenced ASTM/ISO methods).
- Data & analysis: Record TG curves, analyze mass‑gain vs mass‑loss kinetics, detect spalling, re‑oxidation, breakaway oxidation; produce a detailed test report per Clause 10.
Practical applications and users
- Materials engineers and corrosion scientists assessing oxidation, volatilization and spallation behaviour of metals and alloys at elevated temperatures.
- R&D labs, quality control, and failure‑analysis teams in industries such as power generation, aerospace, petrochemical, and metal production where high‑temperature corrosion resistance is critical.
- Test laboratories implementing standards for reproducible TG measurements to compare materials, coatings and protective atmospheres.
Related standards
- ISO 21608 (isothermal oxidation tests) and ISO 13573 (thermal cycling tests) - methods based on discrete mass measurements.
- Calibration and specimen preparation references: ASTM E3, ASTM E220, ASTM E230, ASTM E407, ASTM E1350; dimensional standards ISO 3611 and ISO 13385‑1.
ISO 4215:2022 provides a standardized, automated TG framework to generate continuous, quantitative corrosion kinetics data - essential for material selection, coating evaluation, and lifetime prediction under high‑temperature corrosive environments.