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An investigation of phase transformation and crystallinity in laser surface modified H13 steel

Aqida, S.N, Brabazon, D. and Naher, S. (2012). An investigation of phase transformation and crystallinity in laser surface modified H13 steel. Applied Physics A: Materials Science & Processing, 110(3), pp. 673-678. doi: 10.1007/s00339-012-7149-2

Abstract

This paper presents a laser surface modification process of AISI H13 tool steel using 0.09, 0.2 and 0.4 mm size of laser spot with an aim to increase hardness properties. A Rofin DC-015 diffusion-cooled CO2 slab laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, overlap percentage and pulse repetition frequency (PRF). X-ray diffraction analysis (XRD) was conducted to measure crystallinity of the laser-modified surface. X-ray diffraction patterns of the samples were recorded using a Bruker D8 XRD system with CuKα (λ = 1.5405 Å) radiation. The diffraction patterns were recorded in the 2θ range of 20 to 80°. The hardness properties were tested at 981 mN force. The laser modified surface exhibited reduced crystallinity compared to the un-processed samples. The presence of martensitic phase was detected in the samples processed using 0.4 mm spot size. Though there was reduced crystallinity, a high hardness was measured in the laser-modified surface. Hardness was increased more than 2.5 times compared to the as-received samples. These findings reveal the phase source of the hardening mechanism and grain composition in the laser-modified surface.

Publication Type: Article
Additional Information: The final publication is available at Springer via http://dx.doi.org/10.1007/s00339-012-7149-2
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
T Technology > TJ Mechanical engineering and machinery
Departments: School of Mathematics, Computer Science & Engineering > Engineering
School of Mathematics, Computer Science & Engineering > Engineering > Mechanical Engineering & Aeronautics
Related URLs:
URI: http://openaccess.city.ac.uk/id/eprint/14579
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