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

Aqida, S.N, Brabazon, D. & 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

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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.

Item 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
Divisions: School of Engineering & Mathematical Sciences > Engineering
Related URLs:
URI: http://openaccess.city.ac.uk/id/eprint/14579

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