VAC AERO Press Release The aim of our Newsletter is to facilitate discussion among our customers, technical and educational communities and suppliers on a variety of metallurgical issues, processes, technologies and equipment. Please click here to Sign up for our Newsletter
Archives for August 2007
Vacuum Hardening High-Strength Steels: Oil Vs. Gas Quenching
High strength steel alloys, such as 4340M, 300M, and others, are most commonly used in the manufacture of landing gear components. These alloys are hardened and tempered to produce ultimate tensile strengths exceeding 280 ksi (1,930 MPa). Vac Aero International processes landing gear components for most of the major commercial and military aircraft programs.Vacuum heat treatment offers an alternative method to traditional salt-bath and controlled-atmosphere furnace hardening techniques for high strength steels, such as AISI 4340M and 300M. However, heat treaters must be prudent when choosing between oil and gas quenching for vacuum hardening of high strength steels, because each process has its advantages and disadvantages.
Prior to 1980, Vac Aero used salt bath heat treating for hardening landing gear components (Fig. 1). While salt bath heat treating is still widely used today, it has some inherent disadvantages. For example, even though parts are thoroughly washed after processing, there is still a risk that corrosive salt residues can become trapped in narrow recesses or blind holes. In addition, the washing process itself generates large volumes of contaminated waste liquid, which must be properly disposed of. Also, salt baths generate hazardous fumes, create operator safety concerns, and present a high risk of accidental fire. BY JEFF PRITCHARD
Advanced Techniques For Distortion Control During Vacuum Oil Quenching
High strength steels based on the 43XX series are commonly used for aircraft landing gear components because of their desirable mechanical properties. To achieve optimum mechanical properties, these alloys are usually heat treated by quenching in oil from the hardening temperature, then tempered. This produces a microstructure with high strength and excellent toughness, ideal for applications involving heavy loading and cyclic fatigue. During hardening, internal stresses created from the thermal shock of direct oil quenching almost always cause some degree of distortion in the heat treated component. A final machining allowance is often left on critical dimensional features to compensate for distortion. However, due to the difficulty of machining these alloys in the hardened condition, machining allowances must be minimized.
Many heat treaters have developed hot straightening techniques to reduce quench distortion. However, these techniques are very labour intensive and often involve expensive tooling. In the current environment of cost and lead-time reduction, reducing distortion during thermal processing has become a primary objective for heat treaters of landing gear components. Interrupted quenching techniques such as ausbay quenching offer good potential for reducing quench distortion. Shown in Figure 1 is an isothermal transformation (I-T) diagram for 300M (4340M) alloy, the most commonly used steel for ultra-high strength aircraft applications. The I-T diagram illustrates the microstructural transformations the steel undergoes over time at constant temperature. Superimposed on this diagram is a curve depicting the cooling rate required for successful ausbay quenching. BY JEFF PRITCHARD
New Office in Poland’s Aviation Valley
VAC AERO Press Release, July 30, 2006 VAC AERO has opened a new customer support office in Rzeszow, Poland. Rzeszow is located in the heart of Poland’s Aviation Valley, home to a growing number of international aerospace companies. Through it two Polish facilities, VAC AERO is providing heat treating services and furnace equipment to leading […]
VAC AERO Expands Heat Treating Services and Furnace Manufacturing in Poland.
VAC AERO Press Release, July 30, 2006 VAC AERO Kalisz Sp. z o.o. is expanding its heat treating operations with the addition of a second vacuum furnace. The facility, located in Kalisz, Poland, offers vacuum heat treating and brazing services, thermal spray and inorganic coatings and metallurgical laboratory services. The furnace was designed and built […]
Exhibition Award at European Trade Show
VAC AERO Press Release, July 22, 2006 VAC AERO Manufacturing Polska recently won the Acanthus Aureus Medal at the Surftec Exhibition in Poznan, Poland. The prize is awarded by the exhibition organizers to the display judged best achieving the marketing strategy of the exhibitor. The exhibition team was headed by Alena Iwanowska, Marketing Manager at […]
Come visit us at the ASM Heat Treat Show
Come visit us at the ASM Heat Treat Show at the Detroit COBO Center. If you plan on attending the show, please be sure to stop by our booth # 1115 to learn more about our latest vacuum furnaces, and most importantly… we’re interested in learning about you, your business, and your needs. See you there! Date: […]