Radiant heat treatment: process vies with localized approach.

A new cost-effective technology to heat treat ferrous materials promises higher quality, reduced cycle times, and more applications than other comparable methods. Radiant heat treating (RHT), offers numerous advantages over other localized heat treating services, such as induction, flame, laser, and electron beam. (See table 1).

RHT heat treats most carbon steel and steel alloys, including tool steels and martenistic stainless steel. With RHT, technicians can perform a variety of heat treatments such as stress relief, quench and temper, austemper, martemper, and anneal to produce the desired hardness range and/or microstructure.

The process can heat treat selective areas or entire surfaces of flat, cylindrical, or complex shapes. Parts may measure more than several square feet. While the overall process of induction heating can produce a hardening depth from 0.010[inch] to 0.250[inch], an individual induction unit is limited to a much narrower range. The specific hardening range depends on a number of variables, including the power source operating frequency as well as the shape and number of tuns of the induction coil. In contrast, the hardening depth for one RHT unit can be electronically adjusted to heat treat from 0.010[inch] to more than 0.500[inch] deep without changing equipment.

Unlike induction heating, RHT can easily heat treat a fiat part with a wide variation in cross sectional thickness or a cylindrical part with several different diameters. Even a part that requires deep hardening in one area and shallow hardening in another can be heat treated in one step using a RHT furnace.

Process tooling

Hardening with RHT results in cost reductions because it requires no part specific tooling such as an induction coil or electrode. For induction heating, the energy source to part distance, or air gap, is generally 0.06[inch] to 0.08[inch] while that of RHT can be as broad as 5[inches]. The part heating rate for RHT is independent of the energy source to part distance.

The RHT process also offers a range of other advantages including:

* Areas can be hardened at one time by using an electronically adjustable heating ramp and soak sequence. Yet, if necessary, parts can be progressively scanned.

* Depending on the specific requirements, RHT's heating rate may actually be faster than that of induction hardening. Due to this capability and RHT's process flexibility, skilled personnel can heat treat a part without damaging a nearby temperature sensitive coating, joint, or adjacent material.

* Technicians can heat treat individual or multiple parts simultaneously. Multiple parts may consist of a single part number or a family of similar parts.

* Parts can be heat treated in a variety of environments including open air, protective, or vacuum to accommodate a wide range of part requirements. [TABULAR DATA FOR TABLE 1 OMITTED] After parts are heated to the appropriate temperature, they may be quenched in water, oil, air, or a polymer.

Whether the part shape is flat, cylindrical, or complex, most ferrous parts can be heat treated with RHT. Using RHT may result in cost reductions and quality improvements.

Adaptive Coating Technologies (ACT) LLC, Waunakee, WI, developed RHT as part of a Small Business Innovation Research (SBIR) award. ACT is currently developing RHT for a Phase II SBIR project on armor plate fabrication. In Phase I, ACT successfully heat treated 1/2[inch] thick titanium/steel plates to a hardness of 60 Rc. Numerous commercial applications for RHT exist in the agriculture, mining, pump, oil, aerospace, and automotive industries.

For more information from Adaptive Coating Technologies LLC, Waunakee, WI.