Dissertations and Theses @ UNI


Open Access Dissertation


Steel--Metallurgy; Steel--Heat treatment; Lasers--Industrial applications;


The problem of this exploratory study was to determine the strength of the bivariate correlational relationship between microhardness readings converted to Rockwell values and eddy current values of laser heat-treated AISI 1045 steel. Further, the microstructure was analyzed to determine the microstructural changes formed by laser surface treatment utilizing a carbon dioxide laser.

The purpose of this study was to investigate the microhardness and depth of hardness formed by laser surface treatment, to develop a measure of correlation between microhardness and eddy current values, and to study microstructural changes formed by the laser surface treatment. This knowledge could be used to verify hardness by using nondestructive testing techniques.

The study was designed to perform a laser surface treatment of steel samples and then determine hardness of the material by both destructive and nondestructive testing methods. Ten samples were treated at three separate scanning rates of 22, 30, and 35 IPM respectively. A Rockwell hardness test was used for the destructive analysis. An eddy current analysis was used for testing hardness for the nondestructive method.

Six samples from each scanning rate for a total of 18 samples were used for the comparison between testing methods. Data analyses included the use of descriptive statistics, ANOVA, Pearson Product-Moment Correlation, and Regression Analysis. The data collected from the samples were examined at the .05 level of significance.

Based on the data collected from this study, it was found that there was a statistically significant relationship in hardness between Rockwell values and eddy current values at the p < .05 significance level. However, it was also concluded that there were no significant differences between Rockwell and eddy current values for any of the individual scanning rates.

Given the outcomes of this study, recommendations for further study were warranted and may be utilized to further define the relationship between Rockwell hardness values and eddy current analysis. It was also recommended that this study be replicated using a larger sample size.

Year of Submission


Degree Name

Doctor of Industrial Technology


Department of Industrial Technology

First Advisor

Mohammad F. Fahmy, Chair

Second Advisor

Teresa J.K. Hall, Co-Chair

Date Original


Object Description

1 PDF file (ix, 101 pages)



File Format


Included in

Metallurgy Commons