• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.3
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• pp.16-21
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• 2018

The effect of heat treatment on the fatigue crack growth behavior in welded joints between the heat-affected zone (HAZ) of SA 508 Cl.3 low-alloy steel and HAZ of AISI 316L stainless steel is investigated. When the crack propagates across SA 508 Cl.3 or AISI 316L SS and HAZ into the weldment, the fatigue crack growth rate (FCGR) in the HAZ region does not change or decrease despite the increase in stress intensity factor ${\Delta}K$. The residual stress at the HAZ region is more compressive than that at the base Δ materials and weldment. The effect of the welding residual stress on the crack growth behavior is determined by performing a residual stress relief heat treatment at $650^{\circ}C$ for 1h and subsequent furnace cooling. The FCG behavior in the HAZ region in the as-welded specimen and the residual stress relief heat-treated specimen is discussed in terms of the welding residual stress.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.3
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• pp.5-15
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• 2007

A welding structures is generally composed of dissimilar steel materials in order to reduce weight cost, and has a gap to fill the welding agent. Also, heat flow analysis should be fulfilled for structure existing of gap to figure out residual stress which is generated after welding. Since mechanical properties of welding structure composed of dissimilar steel is more fragile than mechanical properties of welding structure consisted of same material, heat flow analysis verifying this should be fulfilled as well. Therefore, on this research, heat flow analysis about dissimilar steel weldment consisted of gap existing AISI304 and AISI630 is practiced so that it could be a basic data of research about mechanical properties of gap existing dissimilar steel welding part which is going to be studied later on. During heat flow analysis, heat input model which based on Gaussian profile and using volume heat flux was newly consisted and applied. In addition, for verifying of analysis on this research, gap existing dissimilar steel weldment which had gap of 0.25mm and was welded using Nd-YAG. The welding profile and temperature distribution for weldment during welding was compared to the result which was gotten through heat flow analysis. Both of those results corresponded each other.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.779-780
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• 2010

• Journal of Welding and Joining
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• v.26 no.2
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• pp.37-42
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• 2008

• The Journal of the Acoustical Society of Korea
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• v.38 no.3
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• pp.334-339
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• 2019

In this study, the vibration test method to nondestructively evaluate the possibility of vehicle BSR (Buzz, Squeak, Rattle) noise generation in spot-welded structures was proposed. The weld quality was predicted by analyzing the local vibration transmission characteristics for the beam-shaped structure attached to testing spots. The bending stiffness was evaluated from the identified vibration properties. From the change in the stiffness, the weld quality was evaluated. For verification of the proposed method, the welded specimens were fabricated with partial changes in welding parameters. The local vibration transfers were measured. The frequency bands affected by the weld quality was identified. The capability of evaluating the welding parameters including defect position and quality variations was investigated. The proposed method enables fast quality evaluation to minimize the possibility of BSR noise generation in the manufactured vehicle.

• Journal of Ocean Engineering and Technology
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• v.1 no.1
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• pp.120-126
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• 1987

In this paper, the optimizing investigation of characteristics of underwater welding by a gravity type arc welding process is experimentally carried out by using the .phi. 4mm ilmenite type of domestic coated welding electrodes for welding the domestic marine structural steel plates of 8mm thickness in order to develop the underwater welding techniques in practical use, resulting in the quantitative analysis possibility for the relationship between the mechanical propernical properties of underwater welded joint HAZ and the welding heat input.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.199-201
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• 2006

The wetting balance test was carried out to compare the wettability of Sn-Xwt%Cu($0{\sim}3$wt%) solders. And, IMCs which were formed at interface between solders and substrates were investigated by using XRD(x-ray diffractometer), SEM(scanning electron microscope) and EDS(energy dispersive spectroscope). The value of ${\gamma}_[fl}$ and(${\gamma}_{fs}-{\gamma}_{ls}$) had a tendency to increase with increasing wetting temperature. The activation energy that was calculated between the bare Cu substrate and flux was increased in the following order Sn-0.7wt%Cu(68.42 kJ/mol);Sn-3.0wt%Cu(72.66 kJ/mol);100wt%Sn solder(94.53 kJ/mol).

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.202-204
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• 2006

The reliability of insert mounted components has been considered as their life time was getting increased. The spread of crack and the growth of IMC(intermetallic compound) were observed by SEM(scanning electron microscope) and EDS(energy dispersive spectroscope). The cracks in Sn-37wt%Pb under thermal shock test were found earlier than other solders(Sn-3.0wt%Ag-0.5wt%Cu and Sn-0.7wt%Cu-0.01wt%P). The IMC thickness was increased with increasing number of thermal shock cycles in the following order : Sn-0.7Cu-0.01P; Sn-3.0Ag-0.5Cu; Sn-37Pb

• Proceedings of the KWS Conference
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• 2008.05a
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• pp.11-11
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• 2008

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.206-208
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• 2006

The reliability of BGA (ball grid array) package with OSP (organic surface preservative) surface finish under thermal cycle was investigated by using SEM (scanning electron microscopy), EDS(energy dispersive spectroscopy), image tool and ball shear test. The IMCs (intermetallic compounds) were increased with increasing number of thermal cycles. However, the shear strengths of solder ball were decreased with increasing number of thermal cycles. The order of solders which had the highest shear strength as follow: Sn-3.5wt%Ag-0.7wt%Cu, Sn-0.7wt%Cu, Sn-37wt%Pb.