Title

FATIGUE-CRACK PROPAGATION OF LASER SURFACE REMELTED NODULAR CAST IRON

FATIGUE-CRACK PROPAGATION OF LASER SURFACE REMELTED NODULAR CAST IRON

Authorship

ŠTURM, ROMAN; GRUM, JANEZ

ŠTURM, ROMAN

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GRUM, JANEZ

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DOI

10.5151/2594-5327-17032

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Abstract

Laser surface remelting (LSR) of nodular cast iron is applied to surface modification and is suitable for manufacture of various machine and tool parts. Usually studies of remelted layers include microstructural and microchemical analyses and occasionally, if the research is exact, also measurements of residual stresses, various wear and corrosion tests. This paper will represent microstructural analyses of the thin surface layer after laser remelting of nodular cast iron 500-7, and further on also the micro-hardness profile. A particular attention is paid to fatigue-crack initiation and propagation tests. The comparison is made between as received nodular cast iron 500-7 and the same material altered with laser surface remelting process. As the crack propagation is normal to the laser remelted layer, the specimens with laser remelted surface of nodular cast iron exhibited higher resistance to fatigue-crack growth in the low stress intensity factor range ∆Kth than as-received nodular cast iron specimens. Also ∆KIC is higher in the case of laser remelted surface.

Laser surface remelting (LSR) of nodular cast iron is applied to surface modification and is suitable for manufacture of various machine and tool parts. Usually studies of remelted layers include microstructural and microchemical analyses and occasionally, if the research is exact, also measurements of residual stresses, various wear and corrosion tests. This paper will represent microstructural analyses of the thin surface layer after laser remelting of nodular cast iron 500-7, and further on also the micro-hardness profile. A particular attention is paid to fatigue-crack initiation and propagation tests. The comparison is made between as received nodular cast iron 500-7 and the same material altered with laser surface remelting process. As the crack propagation is normal to the laser remelted layer, the specimens with laser remelted surface of nodular cast iron exhibited higher resistance to fatigue-crack growth in the low stress intensity factor range ∆Kth than as-received nodular cast iron specimens. Also ∆KIC is higher in the case of laser remelted surface.

Keywords

Laser surface remelting; Nodular cast iron; Fatigue; Crack propagation.

Laser surface remelting; Nodular cast iron; Fatigue; Crack propagation.