Volume 14, Issue 1 (January 1986)
Use of X-Ray Diffraction with the Gaussian Curve Method to Evaluate the Hardening in Quenched Steels
An X-ray diffraction line will broaden considerably when steels transform to martensite on quenching. Slack quenched steels contain a mixed martensite and fine pearlite structure which produces an anomalous diffraction line profile with a sharp peak superimposed on a broad base. The sharpness of the diffraction line peak can be measured by using a constant of the Gaussian curve fitted to the peak. This constant (denoted GCP) for completely hardened steels increases with increasing carbon content up to 0.7 wt% carbon. At higher carbon contents, the GCP becomes almost constant. Also, the GCP increases with increasing hardness along a single curve independently of carbon content. The GCP for the slack quenched steels is smaller than that for the completely hardened steels. Extent of hardening of the slack quenched steels having a sharp diffraction line peak can be evaluated rapidly and nondestructively by comparing their GCP value with that for the completely hardened steels.