Metallurgical Heat Treatment: Verifying Metal Quality Using Eddy Current NDT

The manufacturing process relies heavily on materials and components that meet their specifications for structure, strength, and quality. Some materials being used in the process may require alteration in their properties to meet these specifications. Metallurgical heat treatment is one of the widely adopted methods to change the properties of these metals to meet the industry specification. These metals, however, must be tested after heat treatment for the verification of their quality.

Among the various nondestructive testing (NDT) methods, eddy current testing (ECT) provides the most efficient results by identifying the material structure differences. In this article, we will discuss why ECT is the best choice for verifying the quality of the heat-treated metal component.

Understanding Metallurgical Heat Treatment 

Metallurgical heat treatment involves the careful heating and cooling of a metal or alloy in a controlled environment to alter its physical or chemical properties. Typically, metallurgical heat treatment is used to:

• Alter the hardness or softness of the metal
• Increase strength
• Increase machinability
• Improve formability 
• Achieve required dimensional stability 
• Improve electrical or magnetic properties of the metal

A metallurgical heat treatment changes the material structure of the metal component during the process of constant heating and cooling. The resulting flaws and irregularities of the treated component can be hard to manually detect. To combat this, eddy current testing can be used to test and verify the quality and integrity of the heat-treated metal component. Advanced ECT tools and equipment can be used to reliably detect the deviation during the inspection process.

Advantages of Using Eddy Current Technology for Verifying Metal Quality

Metallurgical heat treatment alters the metallic structure of the treated component. Eddy current testing is an effective NDT method for inspecting such components. It addresses the shortcomings of visual inspection or other testing processes such as cutting, polishing, and etching of samples, which are often ineffective in detecting the flaws and cracks, or any other irregularities in the heat-treated material.

Eddy current technology uses an electric coil to induce a magnetic field in the conductive metal like steel to detect the flow of current within the metal component. Any irregularities or deviations in the metal can be easily detected with any change in current flow. Advanced ECT probes can sense these changes without the need to damage the material. Manufacturers can also use these instruments, probes, and software to achieve faster inspection and repeatability in testing. ECT solutions for treated material provide reliable flaw detection for quality verification.

ECT metallurgical heat treatment verification is widely used by manufacturers for hardness, depth, or flaw testing of various components. Automotive, aerospace, and other transportation industries use ECT to reduce the risk associated with potential flaws in metal components. In the automotive industry—for example—gears, transmission shafts, and wheel bearings require frequent inspection for quality verification.

Eddy Current NDT for Metallurgical Heat Treatment Testing 

There are critical safety and economic risks associated with flaws and irregularities in the manufacturing process. Eddy current technology is preferred by manufacturers to detect the deviations in the depth or hardness of the material exposed to metallurgical heat treatment. It can also inform about the parts that have not been heat-treated.

Advanced eddy current probes can easily identify if the material has been properly heat-treated. Manufacturers can reduce downtime and improve productivity with eddy current testing by identifying and preventing defective pieces that may degrade the quality of the product or put human lives at risk.  

Zetec is a leader in high-performance eddy current testing solutions for metallurgical heat treatment, helping clients ensure asset integrity and product quality. Contact us today to learn how Zetec delivers solutions to optimize your productivity, safety, and cost of ownership goals.