07.20.26
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It takes a lot of science and a ton of organization to turn drawings and documents into commercial, civilian and military aircraft. It’s hard work—and it’s getting harder. Prices are rising. Supply chains are unpredictable. Maintaining safety is paramount.
En un momento en el que los fabricantes de equipos originales se ven sometidos a una gran presión para cumplir con sus obligaciones y, al mismo tiempo, preservar la calidad y la seguridad de las piezas, las asociaciones sólidas con los proveedores -incluidas las que se establecen con los procesadores térmicos- pueden cambiar las reglas del juego.
why precision matters in aerospace heat treating
La búsqueda de aviones más rápidos, ligeros y eficientes ha impulsado el desarrollo de innumerables aleaciones complejas. Y para que esas aleaciones funcionen como se han diseñado, han surgido tratamientos térmicos igualmente complejos.
The development of these parts and the advanced heat treatments necessary for them to achieve superior mechanical properties have made precision critical at every point in the supply chain.
what are common alloys used in aerospace components?
Aircrafts feature a wide variety of complex materials. Manufacturers must balance important design and material selection concerns to produce long-lasting parts at reasonable costs.
In a game of tradeoffs, the options are almost endless. Heat treaters play an important part in sorting through the choices to achieve the right balance of a diverse array of alloys.
Complex thermal processes have emerged to match the complexity of alloys developed in the pursuit of faster, lighter and more efficient aircraft.
aluminum alloys
Aluminum alloys have been crucial to aerospace material and design advances for decades. As production techniques have matured, aluminum alloys like 6061 helped make aircraft lighter and sturdier.
Today, modern aluminum alloys remain integral in some aerospace applications due to their high strength-to-weight ratio.
Common types include:
- Aleaciones 5xxx con silicio y manganeso que son relativamente trabajables y se caracterizan por su alta dureza y alta resistencia a la tracción a pesar de su baja densidad.
- Las aleaciones 2xxx se utilizan habitualmente para el servicio estructural y como elementos de fijación y remaches.
- Aleaciones 7xxx que también se comportan bien en aplicaciones estructurales y que cuentan con una gran tenacidad y resistencia al agrietamiento por corrosión bajo tensión.
aleaciones de titanio
Titanium and titanium alloys are commonly used in critical aircraft applications where resistance to constant stress is necessary.
Ti6Al4V, a titanium formula containing aluminum and vanadium as alloying elements, is the most popular.
It’s known for its performance under constant severe motion in the cold sections of jet engines. Ti6Al4V is often specified for discs, ducts, turbine blades and bearing housings. Slight tweaks to the formula result in excellent performance in cryogenic temperatures. It’s also sometimes used to make fasteners.
El titanio funciona bien en muchos entornos aeroespaciales, pero no se utiliza tan ampliamente como muchos en la industria desearían. Esto se debe a que el elemento es difícil de extraer y procesar. Es posible que su uso se generalice a medida que mejoren las técnicas de extracción y procesamiento.
nickel alloys
Aleaciones de níquel are also lauded for their performance in high-stress service environments. They’re generally very resistant to corrosion, making them ideal for use in jet engine components in constant motion and subject to high heat and corrosive gases.
Nickel alloys are widely used in critical service environments due to their corrosion resistance and performance under high stress.
Common aerospace nickel alloys include:
- WASPALOY y sus variantes, que son muy resistentes a las altas temperaturas.
- Inconel 718 and Inconel 625, each of which boasts high strength in hot environments; 718 is stronger than 625 but 625 is more corrosion-resistant.
- La aleación 36, que conserva las propiedades dimensionales a altas temperaturas y se especifica a menudo para la instrumentación compleja de los aviones.
- Alloy 230, which resists corrosion under high stress and is suited for cold section service.
- PWA 1484, una fórmula muy resistente a la fluencia a alta temperatura. Las alternativas son las aleaciones René N5 y N636, entre otras.
cobalt alloys
Cobalt alloys such as L-605 exhibit good oxidation resistance and high strength at elevated temperatures. They’re commonly used in turbine rotors, nozzle diaphragm valves, springs, and other components.
stainless steel alloys
Aleaciones de acero inoxidable are among the most versatile in modern industry. From automotive to power generation to pharmaceutical applications and beyond, stainless steel alloys are widely specified for their excellent corrosion resistance.
Las siguientes fórmulas de acero inoxidable se utilizan ampliamente en una amplia gama de entornos aeroespaciales:
- 304, utilizado en los depósitos de combustible y en algunos componentes estructurales no sometidos a temperaturas muy elevadas.
- 309, una fórmula resistente al calor que contiene cromo y níquel adicionales.
- 316, 316L, 321, S30415 y S30815, todos ellos más resistentes al calor y adecuados para su uso en sistemas de escape, motores y algunos servicios estructurales de alta temperatura.
- 17-4Ph, una fórmula que contiene aleaciones de cobre y niobio y que es comparable al inoxidable 304, pero que se elige cuando se desea una mayor resistencia a la corrosión.
how aerospace alloys are heat treated
Process control is crucial. In aerospace, there’s no room for error.
Many aerospace components sustain constant strain and motion and serve in extremely hot or cold environments. For parts like these, complex and precise heat treatments are necessary.
Hornos de vacío are ideal for hardening and strengthening aerospace components for a couple of reasons:
- Parts treated in vacuum furnaces cannot oxidize or become otherwise contaminated when atmosphere is removed from the chamber.
- These furnaces are built to include process controls that allow metallurgists to design the complicated treatment cycles that fulfill the industry’s strict specs.
Algunos proyectos vienen con especificaciones que dictan los parámetros exactos de tratamiento que debemos seguir. Otros pedidos especifican tratamientos basados en las propiedades que deben presentar las piezas, y nos corresponde a nosotros desarrollar el tratamiento que lo haga posible. En cualquier caso, confiamos en nuestro experimentado equipo de metalúrgicos y en los equipos más avanzados del sector.
Vacuum furnaces operating in AST-Paulo’s Cleveland Division routinely execute complex day-long treatments that top 2,400 degrees Fahrenheit.
Our team of metallurgists can:
- Create treatments that feature very slow ramp rates (down to around 1 degree per minute). This ensures that parts reach the required treatment temperature slowly and evenly, which promotes proper solutionizing.
- Fine-tune thermocouples to help our furnaces sustain temperatures to within +/- 2 degrees for an extended period.
- Using programmable logic controllers (PLCs), we can apply correction factors to treatments in progress. Dozens of sensors monitor around 1,000 different variables in real time and trigger alarms if out-of-spec conditions are observed.
Earning and maintaining key certifications is just as important for aerospace thermal processors as understanding materials and metallurgy.
There’s more to thermal processing for the aerospace industry than an in-depth understanding of materials and metallurgy. Earning and maintaining key certifications is equally critical. Read on to learn about the industry’s most rigorous certification and the benefits of working with providers who’ve earned it.
what are the requirements for nadcap-approved heat treaters?
Nadcap requirements are quite prescriptive. Other industry standards programs give suppliers varying amounts of leeway en route to achieving the benchmarks they set. Nadcap features no such liberty.
Los tratadores térmicos homologados por Nadcap deben cumplir los requisitos relativos a todos los aspectos de su funcionamiento, entre ellos
- The types, sizes, and capabilities of heat treating equipment used to treat aerospace and defense components.
- The details of how certain components must be treated (for instance, we need documentation showing our vacuum brazing or other solution treating operations pass muster according to the Nadcap program).
- El grado de precisión en la pirometría (medición de la temperatura a distancia) que debe existir en los hornos de tratamiento térmico.
- Garantizar que las reparaciones de los hornos se realicen de acuerdo con las normas.
- Las propiedades de los aceites de temple adecuados y las pruebas de calidad que deben superar los aceites antes de su uso.
- La formación del personal que maneja los equipos utilizados en el tratamiento térmico aeroespacial y de defensa.
Nadcap starts as acrucial requirement and ends as a mutually beneficial asset.
Becoming a Nadcap-approved heat treater requires proving you have the equipment and processes in place to treat safety-critical aerospace and defense components. Keeping the certification is all about maintaining the mountain of documents showing you’re continually able to meet the strict requirements.
what are first article inspections and AS9102 requirements in heat treating?
Uno de los principios de garantía de calidad más importantes de la industria es la inspección del primer artículo (FAI), es decir, la inspección sistemática de las piezas nuevas para garantizar que funcionen como se han diseñado.
Aerospace, automotive, medical, and other industries all have FAI requirements. In general, these inspections entail thorough investigation of parts pulled from the first-ever batch to verify that:
- Se utilizó el material exacto especificado para una pieza determinada.
- Se han seguido los métodos de fabricación o acabado detallados en las especificaciones.
- Las características de las piezas resultantes de la fabricación o el procesamiento están dentro de las tolerancias establecidas en las especificaciones.
In the aerospace industry, SAE AS9102 standardizes the documentation that industry suppliers must provide to meet OEMs’ FAI requirements.
Informes FAI para tratadores térmicos
Because heat treatment of aerospace components is so critical to their end use, heat treatment documentation for FAI parts is quite extensive. Every aspect of heat treatment is documented, including:
- La inspección de las piezas incluso antes de que se procesen para verificar que cumplen las tolerancias iniciales establecidas en las especificaciones.
- Heat treatment parameters including type of treatment, how long the treatment lasts, how hot the furnace gets (and even how quickly or slowly that temperature is reached), and the way the part is quenched.
- The verification of post-treatment variables like hardness, tensile strength, yield strength, and critical dimension characteristics against tolerances stated in specs.
Este último punto es muy importante. El tratamiento térmico casi siempre distorsiona las piezas: es el precio que conlleva la mejora de las propiedades mecánicas. Las inspecciones del primer artículo ayudan a los tratadores térmicos y a los clientes a determinar si los procesos especificados darán lugar a cantidades aceptables de distorsión o si es necesario cambiar las especificaciones de diseño, material, fabricación y procesamiento.
reduce risk with the right nadcap-certified heat treater
When it comes to managing quality for aerospace components, every detail must be documented and scrutinized. Nothing can be left unplanned.
At AST-Paulo, our cross-functional team applies its heat treatment expertise to the information we gather about part design, material and manufacturing. This intensive review allows us to flag potential problems earlier in the process and, when possible, recommend upstream tweaks that will result in parts that pass inspection.
Our advanced process tracking system ensures nothing slips through the cracks by recording process information in real time and alerting operators if furnace conditions such as pyrometry slip outside of the tolerances defined in treatment specs.
Together, with a team of expert metallurgists and advanced equipment, we provide heat treatments that are successful and highly repeatable.
Ready to make your heat treating more precise and repeatable? Partner with AST-Paulo on your next project.
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