Industrial Steel Treating offers controlled atmosphere gas carburizing services. The carburizing process enhances parts with a hard, wear resistant surface, and a fully hardened martensitic core.

Desired part core hardness is designed by customer product engineers via material selection. Desired part case depths are designed by product engineers, and controlled by several heat treat process variables.

A part’s carburized surface is produced by diffusing carbon into the surface of the heated parts via carbon rich carrier gasses. IST carburizes in controlled atmosphere furnaces, where endothermic gas and natural gas supply nascent carbon to the surface of the heated parts. The four main carburizing process variables are temperature, time at temperature, carbon potential of the atmosphere gasses and part loading density.

Temperature control instrumentation continually reviews furnace temperatures and adjusts burner output appropriately. Time at temperature is controlled on continuous belt furnaces by establishing belt speeds, usually in inches per minute. In row-furnaces, time at temperature is described as “minutes per cycle”, in batch furnaces as “hours per event.”

Carbon potential, usually described as % carbon, is a measure of the furnace atmosphere’s capability to provide nascent carbon to the heated surface of the workpiece. It is controlled via oxygen sensing probes placed at designated locations within the furnace; the sensors provide feedback to a system which varies the input of natural gas and air to the furnace in order to balance the process gas appropriately, providing consistent heat treat results.

Part loading density is designed by IST. Each individual part number’s furnace loading is specified on work instructions; output is monitored and recorded from lot to lot. Belt furnace loading is defined as pounds per hour; batch and row furnace loading is defined as pounds per basket layer, the number of layers per basket, and, the number of baskets per load. Additionally, some parts may require stacking or racking in special or common fixtures that enable parts to be oriented relatively the same throughout the furnace load in order to achieve close tolerance dimensional results, or to minimize part contact during the heat treat process.

All of these variables, and others, are tightly controlled in order to achieve high Ppk and Cpk values from lot to lot.

After the designated carburized process, parts can be either slow cooled in atmosphere or quenched into furnace-integral, temperature controlled and agitation controlled oil baths. Slow cooling yields a carburized part that is not fully hardened. At this point, the part can be further machined before re-heating in an atmosphere furnace and quenched in oil, or selectively hardened via an induction process.

Quenching in oil after carburizing fully hardens the parts, and tempering is usually specified by the customer after quenching to relieve stresses in the part from the heat treat process, or to lower part surface and/or core hardness results.

IST’s metallurgical lab facility evaluates the case depth and hardness of each heat treat load, and certifies results.

Gas Carburizing

Carburize Handling System

Carburize Furnace

Controlled Atmosphere Gas Carburizing Capabilities

Case Depths

0.05 mm – 6.5 mm

Case Depth Range Capability

0.05 mm minimum

Part Length Range

0.25 mm to 762 mm

Loading Methods

Bulk Loading
Rack Loading


Batch – load size: 36″ x 72″ x 36″
Continuous Mesh Belt Systems
Data log heat treat attributes
Integral oil quench, or slow cool in protective atmosphere
Integral pre and post-washing systems
Integral tempering systems
Nine-position Continuous Row – load size 36″ x 36″ x 30″ high

Customer Process Specifications

Allison Transmission TPS-301
Arvin Meritor PS 100-299
Axle Tech 02-400
Bendix BN-153-P
Borg Warner 1000-447-232-D
Bosch ES-2510
Caterpillar 1E0101, 1E2204, 1E2297, 1E2298, 1E2318
Chrysler PS-2, MS-4515, MS-5001, MS-5479
Clark Components International (2X- )
Cummins 71886, 71887
Dana SHAES174
Eaton TES-003
Ford W-HTX, W-HT4-1, W-HT4-3, WD951
GM GM6010M, GM6171M
Harley Davidson ES805-41100
Hy-Lift JP HT-1000
Melling Industries M-212-M, M 218-P
SAE J1102M

Trained/Competent Workforce

To attain operational excellence, IST fosters employee development by diversifying employee’s capabilities, enhancing skill sets and creating a climate for action. Cross-trained employees understand all aspects of the heat treat process, and our customer’s needs. Certified employees are capable of receiving, heat treating, inspecting and shipping.

Technology and Knowledge Management

To best manage our customer’s needs, IST continually refines the knowledge management process and improves information technology resources. We utilize best practices to facilitate the transfer of knowledge to all levels of the organization; employees understand our customer’s requirements and act in their best interests.