• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.9 no.1
• /
• pp.70-76
• /
• 2013

Several finite element models for the leak-before-break (LBB) assessment of overlay dissimilar metal weldment were constructed and analyzed to develop a simple finite element modeling method. The J-integral, crack opening displacement (COD) and J-integral distribution along the crack front in thickness direction due to the applied moment were obtained from the analysis results of the constructed finite element models, and studied compared to the previous literatures. It is concluded that the modeling with base material only is simple and produces a slightly conservative results compared to the complex modeling composed with weld metal and base metal in the calculation of J-integrals and COD values which are used for the calculation of fracture toughness and postulated leakage crack length respectively.

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

• Proceedings of the KWS Conference
• /
• 2006.05a
• /
• pp.140-142
• /
• 2006

The bend ductility of Type 410S ferritic stainless steel overlay weld on carbon steel was investigated. Overlay weld that was stabilized with Nb had large columnar ferrite grain and Nb precipitate on grain boundary. And that caused fracture when bend test without concern of PWHT condition. Proper bend ductility at as-welded condition was achieved by refining ferrite grain with addition of $0.04{\sim}0.09%$ Al and $0.2{\sim}0.5%$ Ti that make oxide, carbide and nitride at high temperature.

• Journal of the Society of Naval Architects of Korea
• /
• v.48 no.5
• /
• pp.473-478
• /
• 2011

Welding process generates distortion and residual stress in the weldment due to rapid heating and cooling. Welding distortion and residual stress in the welded structure result in many troubles such as dimensional inaccuracies in assembling and safety problem during service. The accurate prediction of welding residual stress is thus very important to improve the quality of weldment and find the way to reduce itself. This paper presents the simulation of welding-induced residual stress analysis to examine the cause of cracking in the SUS-overlay welding specimen at FPSO Moon Pool structure.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.20 no.6
• /
• pp.562-567
• /
• 2000

Many pressure vessels for power and industrial plant are fabricated from low alloy carbon steels. The inner sides of pressure vessels are commonly weld-cladded with austenitic stainless steels to minimize problems of corrosive attack. Disbonding cracks are often detected at the transition region of welding interlayer, which is serious problem to reliability of pressure vessels. We have developed C-scan system to high speed inspection of overlay weld using DSP(digital signal processor). This system consists of signal processing parts (oscilloscope, pulser/receiver, digitizer, DSP), scanner, program and position controller. The developed system has been applied to a practical ultrasonic testing in overlay weld, and demonstrated high speed with precision

• Journal of Welding and Joining
• /
• v.16 no.2
• /
• pp.73-83
• /
• 1998

This study investigated the relationships between the microstructure and the wear resistance of hardfaced iron/chromium alloys to examine the low stress abrasive wear mechanism. The effects of volume fraction of reinforcing phases(chromium carbide and eutectic phase) were studied. The alloys were deposited once or twice on a mild steel plate using a self-shielding flux cored arc welding process. The low stress abrasion resistance of he alloys against dry sands was measured by the Dry Sand/Ruber Wheel Abrasion Tester (RWAT). The wear resistance of hypoeutectic alloys, below 0.36 volume fraction of chromium-carbide phase (VFC), behaved as Equal Pressure Mode (EPM) for the inverse rule of mixture whereas the wear resistance of hypereutectic alloys, above 0.36 VFC, represented Equal Wear Mode (EWM) for the linear rule of mixture.

• Journal of Welding and Joining
• /
• v.16 no.1
• /
• pp.114-124
• /
• 1998

The effect of matrix phase (austenite, pearlite, martensite) on the low stress abrasion resistance in the chromium-carbide-type high Cr white iorn hardfacing weld deposites has been investigated. In order to examine matrix phase, a series of alloys with different matrix phase by changing the ratio of Cr/C system by heat treatment were employed. The alloys were deposited twice on a mild steel plate using self-shielding flux cored arc welding process. The low stress abrasion resistance of the alloys against sands was measured by the Dry Sand/Rubber Wheel Abrasion Test(RWAT). Even though formation of pearlite phase in the matrix showed higher hardness than that of austenite, there was no observable difference in wear resistance between the pearlite and austenite phase for the same amount of chromium-carbide in the matrix. On the other hand, the formation of martensitic phase,, from heat treated austenitic alloys (high content of Cr), enhanced wear resistance due to its fine secondary precipitates.

• Journal of Welding and Joining
• /
• v.16 no.1
• /
• pp.125-133
• /
• 1998

The effect of volume fraction of Cr carbide phase (Cr CVF) on the low stress abrasion resistance in the chromium-carbide-type high Cr white iron hardfacing weld deposits has been investigated. In order to examine Cr CVF, a series of alloys with varying Cr CVF by changing chromium and carbon contents and the ratio of Cr/C were employed. The alloys were deposited once or twice on a mild steel plate using the self-shielding flux cored arc welding process. The low stress abrasion resistance of the alloys against sands was measured by the Dry Sand/Rubber Wheel Abrasion Test (RWAT). It was shown that hardness and abrasion resistance increased with increasing Cr CVF within the whole test range (Cr CVF : 0.23-0.64). Both primary Cr carbide and eutectic Cr carbide were particularly effective in resisting wear due to their high hardness.

• Proceedings of the KWS Conference
• /
• 2000.10a
• /
• pp.211-213
• /
• 2000

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2011.06a
• /
• pp.78-78
• /
• 2011