Fiber Laser Welding of Direct-Quenched Ultrahigh Strength Steels: Evaluation of Hardness, Tensile Strength, and Toughness Properties at Subzero Temperatures

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Farhang Farrokhi ◽  
Jukka Siltanen ◽  
Antti Salminen
Keyword(s):  
Tensile Strength ◽  
Impact Toughness ◽  
Fiber Laser ◽  
Welding Process ◽  
Fiber Laser Welding ◽  
Butt Joints ◽  
Ultrahigh Strength ◽  
Subzero Temperatures ◽  
Ultrahigh Strength Steels ◽  
Strength And Toughness

The recently developed direct-quenched ultrahigh strength steels (UHSS) possess an appropriate combination of high tensile strength and toughness properties at subzero temperatures down to −80 °C, while simultaneously having low carbon contents, which is beneficial for weldability. In this study, butt joints of Optim 960 QC direct-quenched UHSS with a thickness of 8 mm were welded with a 10 kW fiber laser to evaluate the characteristics of the joints within the range of low to high heat inputs possible for this welding process. The mechanical properties of the joints were studied by subjecting the specimens to a number of destructive tests, namely, hardness and tensile testing, as well as impact toughness testing at temperatures of −40 °C and −60 °C. It was found that high quality butt joints with superior tensile strength and good impact toughness properties at −40 °C could be obtained. However, having a high level of all these properties in the joint narrows the process parameters’ window, and the heat input needs to be strictly controlled.

Fiber Laser Welding of Noncombustible Magnesium Alloy

2008 ◽  
Vol 580-582 ◽  
pp. 479-482 ◽  
Author(s):  
Yuji Sakai ◽  
Kazuhiro Nakata ◽  
Takuya Tsumura ◽  
Mitsuji Ueda ◽  
Tomoyuki Ueyama ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Magnesium Alloy ◽  
Laser Welding ◽  
Fiber Laser ◽  
Vickers Hardness ◽  
Laser Power ◽  
Welded Joint ◽  
Welding Process ◽  
Fiber Laser Welding ◽  
Laser Welding Process

Noncombustible magnesium alloy AMC602 (Mg-6mass%Al-2mass%Ca) extruded sheet of 2.0mm thickness was successfully welded using a fiber laser welding process at welding speed of 10m/min at 3kW laser power. Tensile strength of the welded joint was about 82 to 88% of that of the base metal. Vickers hardness, tensile strength and micro structural properties are also discussed.

Dissimilar unbeveled butt joints of AA6061 to S235 structural steel by means of standard single beam fiber laser welding-brazing

2021 ◽  
Vol 291 ◽  
pp. 116994
Author(s):  
D. Wallerstein ◽  
F. Lusquiños ◽  
R. Comesaña ◽  
J. del Val ◽  
A. Riveiro ◽  
...  
Keyword(s):  
Laser Welding ◽  
Fiber Laser ◽  
Structural Steel ◽  
Fiber Laser Welding ◽  
Butt Joints ◽  
Single Beam

scholarly journals A Study on Determining Weld Joint Hardening and a Quality Evaluation Algorithm for 9% Nickel Weld Joints Using the Dilution Ratio of the Base Material in Fiber Laser Welding

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1308
Author(s):  
Minho Park ◽  
Jisun Kim ◽  
Changmin Pyo ◽  
Jaewoong Kim ◽  
Kwangsan Chun
Keyword(s):  
Laser Welding ◽  
Fiber Laser ◽  
Weld Joint ◽  
Base Material ◽  
Welding Process ◽  
Fuel Oil ◽  
Welding Quality ◽  
Dilution Ratio ◽  
Fiber Laser Welding ◽  
Evaluation Algorithm

The demand for LNG-powered ships and related equipment is rapidly increasing among major domestic and foreign carriers due to the strengthened IMO regulations on the sulfur content of ship fuel oil. LNG operation in a cryogenic environment requires a storage tank and fuel supply system that uses steel with excellent brittleness and fatigue strength. A ship using LNG is very sensitive to explosion and fire. For this reason, 9% Ni is often used, because ships require high quality products with special materials and structural technologies that ensure operability at cryogenic temperatures. However, research to derive uniform welding quality is urgent because the deterioration of weld quality in the 9% Ni steel welding process is caused by high process difficulty and differences in welding quality depending on a welder’s skill set. This study proposes a method to guarantee a uniform quality of 9% Ni steel in a fiber laser welding process by categorizing weld joint hardness according to the dilution ratio of a base material and establishing a standard for quantitative evaluation.

Effect of water depth on weld quality and welding process in underwater fiber laser welding

2017 ◽  
Vol 115 ◽  
pp. 112-120 ◽  
Author(s):  
Ning Guo ◽  
Xiao Xing ◽  
Hongyun Zhao ◽  
Caiwang Tan ◽  
Jicai Feng ◽  
...  
Keyword(s):  
Laser Welding ◽  
Fiber Laser ◽  
Water Depth ◽  
Welding Process ◽  
Weld Quality ◽  
Fiber Laser Welding ◽  
Effect Of Water

Comparison of Mechanical and Microstructural Characteristics in Maraging 300 Steel Welded by PAW and GTAW Processes Submitted to Repair

2016 ◽  
Vol 1135 ◽  
pp. 255-264 ◽  
Author(s):  
Paulo Roberto Sakai ◽  
Deivid Ferreira da Silva ◽  
Sandro Lombardo ◽  
Antonio Jorge Abdalla
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Base Material ◽  
Welding Process ◽  
Repair Process ◽  
High Temperature Strength ◽  
Maraging Steels ◽  
Ultrahigh Strength ◽  
Ultrahigh Strength Steels ◽  
Welding Processes

Maraging steels are a special class of ultrahigh-strength steels which presents a combination of high mechanical strength, excellent toughness, high temperature strength and corrosion resistance. The joint of sheets/plates by welding processes are fundamental for aeronautical and industrial products in addition Brazil has been developing technologies in welding ultrahigh-strength steels such as AISI 4340ESR and SAE 300M steels for its domestic space launch program and has currently decided for the replacement of these steels by Maraging 300 steel in some projects. In this work, we studied the welding process of the Maraging 300 steel for two different routes: Tungsten Inert Gas (TIG or GTAW) and Plasma Arc Welding (PAW). Filler additions were used for both processes. Procedure after any welding demands non destructive testing and sometimes non approved defects considering the usage of the product require for welding repair. Verification of the effects of this operation was made through a simulation of a welding repair for both types of welding. Specimens were submitted to heat treatment consisting of a solution annealing and aging and their microstructures were examined. The microhardness measurements were made on samples with and without repair characterized the fusion and heat affected zones. Specimens were submitted to tensile testing and the fractured surfaces were examined by a scanning electron microscope. Results of microstructure exam revealed the presence of austenite (γ) in FZ (Fusion Zone). After the welding repair simulation, a new different colored zone appeared in the HAZ (Heat Affected Zone) for both processes due to reheating of the sheet provided by the repair process. In the HAZ near FZ an important grain growth due to the heating occurred. Also, close FZ that was submitted to new heating due to repair it was noted an apparent growing of grain size relative to original grain size. The microhardness measurements showed that there is a reduction in hardness in the FZ and the region immediately (fusion line) compared to base material values. After the aging heat treatment a recovery of hardness values took place in these regions but the values themselves remain smaller than the base material. It was observed an increase of values of the microhardness in dark regions in the HAZ provoked by a phenomenon of aging locally due to the dissipation of the heat of the welding process and posterior repair. After aging, those differences disappeared. It was observed that there was not a large difference between the yield and strength limits considering both processes of welding, as well as between both situations after repair. It could be seen that the rupture began in the region near FZ and followed in the direction of the weld bead. The analysis of the fracture surfaces showed that this happened by ductile way, forming dimples.

Effect of Laser-Induced Plume on Welding Process During High Power Fiber Laser Welding

2014 ◽  
Vol 41 (6) ◽  
pp. 0603005 ◽  
Author(s):  
邹江林 Zou Jianglin ◽  
李飞 Li Fei ◽  
牛建强 Niu Jianqiang ◽  
孔晓芳 Kong Xiaofang ◽  
马然 Ma Ran ◽  
...  
Keyword(s):  
Laser Welding ◽  
Fiber Laser ◽  
High Power ◽  
Welding Process ◽  
Fiber Laser Welding

Extraction of Weld Pool Width Feature Based on Visual Sensing during High-Power Fiber Laser Welding

2012 ◽  
Vol 201-202 ◽  
pp. 388-391
Author(s):  
Zi Qin Chen ◽  
Xiang Dong Gao
Keyword(s):  
Laser Welding ◽  
Fiber Laser ◽  
Weld Pool ◽  
High Power ◽  
High Speed ◽  
Welding Process ◽  
304 Stainless Steel ◽  
Fiber Laser Welding ◽  
Weld Pool Width ◽  
Laser Welding Process

In a high-power fiber laser welding process, the thermal radiation of a weld pool contains plenty of information for welding quality, in which the pool width can reflect the welding stability. Thus, extracting the welding pool width of high-power fiber laser welding based on infrared thermal imaging is an important method for monitoring the weld seam quality. In this paper, we studied the 304 stainless steel welded by a 10kW high-power fiber laser continuously. A near-infrared high-speed sensing camera was used to capture the weld pool images. Image algorithms such as median filtering, gray scale stretching, cutting, dynamic threshold mathematical morphology were applied to extract the weld pool image edge, analyze and detect the weld pool width. Welding experimental results showed that the proposed methods could extract the weld pool width, which could reflect the stability status of high-power fiber laser welding process accurately.

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