Dew point (DP) is a function of the furnace atmosphere composition. In a metal processing furnace, maintaining appropriate atmosphere composition is critical to achieving the desired gas/metal reactions and quality and consistency of the treated product. Continuous measurement of DP is always challenging because of particulates and vapor-phase contaminants in sampled gas stream which can potentially accumulate in filtering systems and on sensors. The DP measurement can also be affected by temperature variations within the sampling unit. Thus, DP readings can drift significantly, necessitating frequent cleaning, recalibration, and sensor replacement. Air Products has developed a DP monitoring system that addresses these issues and based on long-term testing at a customer site, drifts/changes of DP readings on calibration gas were not observed after more than one year of operation, without any maintenance. The contamination and drift issues have been mitigated by incorporating an automated self-cleaning and sensor calibration process after pre-set measurement periods. Temperature control of the sensor and the sampling system are also essential to maintain consistency, and can be achieved via various design features. Drifts/changes in DP that are reported through local monitoring/alarms or remotely through cloud server access can also help to address furnace operational issues quickly and efficiently.

As part of a project to identify nondestructive techniques to determine the surface hardness and case depth of carburized steel, Meandering Winding Magnetometers (MWM) measurements were evaluated. MWM technology is based on eddy current testing. Compared to traditional eddy current testing, MWM measurements integrate the generating coil and detection coil into a thin, flexible sensor that can be applied to complex geometries. Conductivity and permeability are measured with MWM equipment to evaluate the properties of carburized steel. For this study, samples of 8620 were carburized to selected hardness and case depths. MWM technology was determined to be an effective method to detect surface hardness. The results of this study are presented and discussed in this paper.

This article examines the critical role of process control in nitriding and ferritic nitrocarburizing (FNC) treatments, focusing on the measurement and regulation of nitriding potential (K N ) and carbon activity (K C ). The author demonstrates how modern sensor technology combined with automated programmable control systems can effectively eliminate process variability and ensure consistent, high-quality outcomes. The discussion covers fundamental principles of K N and K C control through proper utilization of sensors, analysis of key input variables, and the relationship between gas ratios, temperature, and time on treatment results. Various monitoring technologies are reviewed, including hydrogen sensors, CO/CO 2 analyzers, oxygen probes, associated technical challenges, and maintenance requirements. By highlighting the importance of precise process parameter control, the article provides practical insights for achieving repeatable, high-quality surface treatments in industrial applications.