Heat Treating Services

Heat treating services perform thermal treatments to modify the properties of metals and metal alloys. Common processes include annealing, austempering, case hardening, conventional hardening, homogenizing, hot isostatic pressing (HIP), martempering, normalizing, precipitation hardening, shot peening, solution treating, spheroidizing, stabilizing, and stress relieving. There are many other unlisted, specialized, or proprietary heat treating processes for specific metals, glasses, ceramics, and polymers. Some heat treating services perform secondary processes such as development assistance, finishing, coating, grinding, or machining. Others perform laboratory testing and inspection, packaging and straightening, or trucking and shipping. Heat treating services are located throughout the United States and across the world. Many meet International Standards Organization (ISO) requirements or automotive, aerospace, or military specifications. 

Heat treat services that specialize in annealing perform processes such as bright annealing, full annealing, homogenizing, hydrogen de-embrittlement, normalizing, solution treating, spheroidizing, and stress relieving. Homogenization or homogenized annealing heats an alloy to a temperature at which diffusion reduces compositional segregation. Normalized annealing decreases pearlite interlamellar spacing and refines grain size. Typically, the normalizing process consists of austenization followed by air cooling. Solution treating is the first phase in precipitation hardening, a two-step process that ends with aging. Spheroidizing heats steel to a temperature near the austenite-to-ferrite transformation temperature for a long enough time to coarsen and modify its structure. Generally, spheroidizing is used to improve machining properties and the cold-deformability of steel. Stress relieving is a lower temperature annealing process that removes residual stress without causing substantial reductions in strength or hardness. Cryogenic, cold, or sub-zero treatments below the martensite finish temperature are used to obtain conditions or properties such as dimensional or microstructural stability.

Heat treating services perform many processes to harden or strengthen materials. Conventional processes include quenching and tempering, a treatment in which a ferrous alloy is transformed first to austenite and then to martensite. Austempering is a process that quenches cast iron or carbon steel above the austenite transformation ranges in a medium with a high enough rate of heat transfer to prevent the transformation of high temperature formation products. Martempering or marquenching is a hardening treatment in which an austenitized ferrous workpiece is quenched into an appropriate medium whose temperature is maintained at the martensite start temperature (M_s) of the workpiece, and held in the medium until its temperature is uniform throughout – but not long enough to permit bainite to form – and then cooled in air. Case hardening forms and hardens a compositionally modified surface layer within the material. By contrast, hot isostatic pressing (HIP) uses an argon atmosphere or other gas mixtures heated to 3000º F and pressurized up to 100,000 psi. Though not a thermal process, shot peening or blasting is suitable for improving certain mechanical properties. 

Heat treating services use a variety of equipment. Often, conventional furnaces are used with an air-based, protective gas, or vacuum atmosphere. Salt baths are used during aluminum solution treatments to provide a very uniform and stable temperature profile in the furnace to eliminate localized melting.  For localized, field work or selective heat treatment, heat treating services may use flame or torch equipment, induction heating equipment, resistive heating blankets, or laser or electron beam heating equipment. Hot presses may include isostatic units for HIP or cold bending presses for straightening distorted parts.

• Laser Use Heats Up
  Since their development, lasers have experienced limited use in metal heat treating primarily because they were expensive as compared with other common heat treating methods. However, the situation is...
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• Austempering
  Austempering quenches cast iron or carbon steel above the austenite transformation ranges in a medium with a high enough rate of heat transfer to prevent the transformation of high temperature...
  (read more)
• Martempering
  Martempering or marquenching is a hardening procedure in which an austenitized ferrous workpiece is quenched into an appropriate medium whose temperature is maintained at the martensite start...
  (read more)

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