• Proceedings of the KWS Conference
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• 2006.05a
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• pp.59-61
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• 2006

The $CO_2$ laser cladding was conducted on an AC2B alloy with feeding Fe-based powders. A powder feeding rate (PFR) and a travel velocity were related with the cracks adjacent to the Fe/Al interface. Preheating temperature was varied to study the interface crack. Preheating to $250^{\circ}C$ during the laser cladding suppressed the interface crack ratio (ICR). The ICR was limited for the single pass clad and the reciprocating test for the slide wear was conducted on an overlay cladding experiment. Comparing with no overlap overlay, the overlay clad with 50% overlap showed better wear resistance.

• Journal of Welding and Joining
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• v.33 no.5
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• pp.53-60
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• 2015

Laser surface Melting Process is getting hardening layer that has enough depth of hardening layer as well as no defects by melting surface of substrate. This study used CW(Continuous Wave) Yb:YAG and STD11. Laser beam speed, power and beam interval are fixed at 70mm/sec, 2.8kW and 800um respectively. Hardness in the weld zone are equal to 400Hv regardless of melting zone, remelting zone overlapped by next beam and HAZ. Similarly, microstructures in all weld zone consist of dendrite structure that arm spacing is $3{\sim}4{\mu}m$, matrix is ${\gamma}$(Austenite) and dendrite boundary consists of ${\gamma}$ and $M_7C_3$ of eutectic phase. This microstructure crystallizes from liquid to ${\gamma}$ of primary crystal and residual liquid forms ${\gamma}$ and $M_7C_3$ of eutectic phase by eutectic reaction at $1266^{\circ}C$. After solidification is complete, primary crystal and eutectic phase remain at room temperature without phase transformation by quenching. On the other hand, microstructures of substrate consist of ferrite, fine $M_{23}C_6$ and coarse $M_7C_3$ that have 210Hv. Microstructures in the HAZ consist of fine $M_{23}C_6$ and coarse $M_7C_3$ like substrate. But, $M_{23}C_6$ increases and matrix was changed from ferrite to bainite that has hardness above 400Hv. Partial Melted Zone is formed between melting zone and HAZ. Partial Melted Zone near the melting zone consists of ${\gamma}$, $M_7C_3$ and martensite and Partial Melted Zone near the HAZ consists of eutectic phase around ${\gamma}$ and $M_7C_3$. Hardness is maximum 557Hv in the partial melted zone.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.4
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• pp.307-312
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• 2017

Laser cladding has some advantages compared to conventional cladding technologies such as arc welding and thermal spraying. Laser cladding produces a metallurgically well-bonded clad layer with a lower dilution ratio and few defects. Based on the characteristics of a 1-pass clad layer with many parameters, which were investigated in a previous report, it was found that it was essential to overlap a 1-pass clad layer when cladding a large area. In this study, the shape differences of multi-pass clad layers with various overlapping ratios were compared. Then, the alloying element distribution of cladding with a certain overlapping ratio was investigated using EDS and EPMA. As the overlapping ratio increased, the length of the clad decreased and its height increased. In addition, the height of the multi-pass cladding was higher than that of the 1-pass cladding under the same condition. The Fe content of the highly diluted first clad was found to be approximately 20 % in an element analysis. However in the area outside of the first clad, the Fe content was decreased to 10 % as a result of minimum dilution, and a uniform distribution of elements was found.