Resistance spot welding of additively manufactured maraging steels Part I: Nugget formation

Abstract Application of additively manufactured steels is unavoidably involved in the resistance spot welding with conventionally manufactured steels. However, the microstructural evolution of an additive manufactured steel at high temperatures is still unknown, especially for the rapid solidification process. This paper investigated the microstructural evolution of a selective laser melted maraging steel during the rapid solidification process via resistance spot welding. Asymmetrical fusion zone with boat shape was found in the spot weld due to the rougher surface and larger electrical resistance of maraging steel via selective laser melting process. The rapid expansion of fusion zone at end of welding process was caused by the carbide formation at the heat-affected zone of maraging steel via selective laser melting process. Besides, printing orientation affected the surface roughness of a selective laser melted maraging steel and subsequently significantly influence the early stage of formation of fusion zone of additively manufactured maraging steel. We expect that our findings will pave the way to the future application of additively manufactured steels in the industries.

Download Full-text

Resistance spot welding of additively manufactured maraging steels Part II: Failure behavior

Journal of Manufacturing Science and Engineering ◽

10.1115/1.4053276 ◽

2021 ◽

pp. 1-31

Author(s):

Cheng Luo ◽

Yansong Zhang ◽

Michael Oelscher ◽

Yandong Shi ◽

Niels Pasligh ◽

...

Keyword(s):

Selective Laser Melting ◽

Fracture Mode ◽

Automotive Industry ◽

Material Properties ◽

Resistance Spot Welding ◽

Spot Welding ◽

Melting Process ◽

Spot Welds ◽

Laser Melting ◽

Maraging Steels

Abstract Application of maraging steels via selective laser melting process in the automotive industry was unavoidably involved in the resistance spot welding with conventional steels. Due to the rapid cooling rate of welding process, selective laser melted maraging steels with unique chemical components and stack microstructure could induced the different microstructural evolution, resulting in the complicated fracture behavior in the spot welds. This paper developed a FEA model to predict the fracture mode of spot welds of DP600 to maraging steel and the effect of test conditions and printing orientations were studied. A method was proposed to calculate the material properties of fusion zone by introducing the combined effect of melting DP600 and maraging steels via selective laser melting, resulting in the accurate prediction of fracture mode and strength of spot welds. An interlayer with lower strength was found around the fusion zone and the fracture path propagated in the region, resulting in the partial interfacial failure of spot welds. Meanwhile, the printing orientation had no significant effect on the fracture mode and strength of spot welds, but the different material properties of maraging steels could affect the fracture displacement of spot welds. These findings could pave a way to guide the application of maraging steels via selective laser melting process in multiple industries, especially in the automotive industry.

Download Full-text

Welding metallurgy of stainless steels during resistance spot welding Part I: fusion zone

Science and Technology of Welding & Joining ◽

10.1179/1362171815y.0000000015 ◽

2015 ◽

Vol 20 (6) ◽

pp. 502-511 ◽

Cited By ~ 31

Author(s):

M. Pouranvari ◽

M. Alizadeh-Sh ◽

S. P. H. Marashi

Keyword(s):

Fusion Zone ◽

Stainless Steels ◽

Resistance Spot Welding ◽

Spot Welding ◽

Resistance Spot ◽

Welding Metallurgy ◽

Welding Part

Download Full-text

An Exploratory Study on Resistance Spot Welding of Titanium Alloy Ti-6Al-4V

Materials ◽

10.3390/ma14092336 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2336

Author(s):

Ichwan Fatmahardi ◽

Mazli Mustapha ◽

Azlan Ahmad ◽

Mohd Nazree Derman ◽

Turnad Lenggo Ginta ◽

...

Keyword(s):

Fusion Zone ◽

Heat Input ◽

Resistance Spot Welding ◽

Spot Welding ◽

High Heat ◽

Spot Weld ◽

Weld Nugget ◽

Optimum Level ◽

Resistance Spot ◽

High Heat Input

Resistance spot welding (RSW) is one of the most effective welding methods for titanium alloys, in particular Ti-6Al-4V. Ti-6Al-4V is one of the most used materials with its good ductility, high strength, weldability, corrosion resistance, and heat resistance. RSW and Ti-6Al-4V materials are often widely used in industrial manufacturing, particularly in automotive and aerospace industries. To understand the phenomenon of resistance spot weld quality, the physical and mechanical properties of Ti-6Al-4V spot weld are essential to be analyzed. In this study, an experiment was conducted using the Taguchi L9 method to find out the optimum level of the weld joint strength. The given optimum level sample was analyzed to study the most significant affecting RSW parameter, the failure mode, the weld nugget microstructure, and hardness values. The high heat input significantly affect the weld nugget temperature to reach and beyond the β-transus temperature. It led to an increase in the weld nugget diameter and the indentation depth. The expulsion appeared in the high heat input and decreased the weld nugget strength. It was caused by the molten material ejection in the fusion zone. The combination of high heat input and rapid air cooling at room temperature generated a martensite microstructure in the fusion zone. It increased the hardness, strength, and brittleness but decreased the ductility.

Download Full-text

Effect of silica content on mechanical and microstructure behaviour of resistance spot welded advanced automotive TRIP steels

10.21203/rs.3.rs-163804/v1 ◽

2021 ◽

Author(s):

Paranthaman V ◽

Shanmuga Sundaram K ◽

L Natrayan

Keyword(s):

Fusion Zone ◽

Resistance Spot Welding ◽

Spot Welding ◽

Welding Process ◽

Tensile Shear ◽

X Ray Diffraction ◽

X Ray ◽

Trip Steels ◽

Resistance Spot ◽

Spot Welded

Abstract This research investigates the effect of SiC wt% on mechanical and microstructure behavior of transformation induced plasticity (TRIP) 780 steels by resistance spot welding. The resistance spot welded samples were characterized for their properties such as hardness, tensile shear, scanning electron microscope, X-ray diffraction, ductility ratio and elongation. Results showed that the width of the nugget was closely associated with shear failure of the spot welds. X-ray diffraction analysis illustrated that the weld steels chemical composition improved in the heat-affected zones and retained austenite detected due to the influence of Si and C. Sample 4 microstructure exposed the equiaxed dimple and finer dendrites in the fusion zone. It also exhibited maximum force and fracture energy. Nano hardness was significantly decreased in the fusion zone of sample 4 due to the interface among micro alloying elements and the formation of nonmetallic presences that affected the TRIP steel hardness. Low ductility ratios were observed in steel 4 than the other weld steels due to higher tensile shear strength (TSS) and cross-tension strength (CTS) results. Fracture analysis exhibited ductile fracture with dimples and dendrites in the TRIP steels surface. The spot-welded samples mechanical properties are correlated to chemical elements, mainly Si existing in casted TRIP steels through the cooling phase of the resistance spot welding process.

Download Full-text

Resistance spot welding of dissimilar austenitic/duplex stainless steels: Microstructural evolution and failure mode analysis

Journal of Manufacturing Processes ◽

10.1016/j.jmapro.2017.06.005 ◽

2017 ◽

Vol 28 ◽

pp. 186-196 ◽

Cited By ~ 10

Author(s):

M. Alizadeh-Sh ◽

S.P.H. Marashi

Keyword(s):

Failure Mode ◽

Microstructural Evolution ◽

Stainless Steels ◽

Resistance Spot Welding ◽

Spot Welding ◽

Duplex Stainless Steels ◽

Mode Analysis ◽

Resistance Spot ◽

Failure Mode Analysis

Download Full-text

Failure Study of Two Dissimilar Steels Joined by Spot Welding Technique

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.778.262 ◽

2018 ◽

Vol 778 ◽

pp. 262-267

Author(s):

Ali Dad Chandio ◽

Nabeel Ahmed Khan ◽

Rameez Jawaid ◽

Syed Naqi Mohsin

Keyword(s):

Failure Mode ◽

Fusion Zone ◽

Resistance Spot Welding ◽

Spot Welding ◽

Sheet Material ◽

Weld Zone ◽

Resistance Spot ◽

Pull Out ◽

Lap Shear ◽

Dissimilar Alloys

Resistance spot welding (RSW) process is of paramount importance in automotive industry for the fabrication of metallic components. Several dissimilar alloys could easily be joined by resistance spot welding. However, the joining of the stainless steel and galvanized carbon steel is challenging task since weld fusion zone properties are affected significantly. Indeed, the reliability of the component lies in the sound quality of spot weld. The overload failure mode of the weld zone was determined by preparing lap-shear specimens and then carrying out tensile-shear test. Microstructures and hardness of the weld nuggets were also brought under considerations. It was found that weld nugget size and strength of that sheet material which has lower electrical resistance are the controlling factors of the failure mode. The aim of this study was to find out the causes of spot welds failure in terms of parameters favoring the pull-out failure mode, role of fusion zone size (FZS), nugget and base metal by controlling the process parameters.

Download Full-text

Mathematical and Computational Modeling of Resistance Spot Welding Solidification Process

10.1115/detc2021-68155 ◽

2021 ◽

Author(s):

Ruiji Sun ◽

Matthew Higgins ◽

Haiyan H. Zhang

Keyword(s):

Heat Transfer ◽

Mathematical Model ◽

Resistance Spot Welding ◽

Spot Welding ◽

Solidification Process ◽

Welding Parameters ◽

Transfer Model ◽

Optimal Size ◽

Resistance Spot ◽

Model And Simulation

Abstract The paper presents a mathematical model and simulation of resistance spot welding (RSW) of a binary alloy during the final solidification process. After analyzing the heat distribution and heat transfer process, the authors established assumptions for a planar front solidification model. Following the application of initial and boundary conditions, the model is developed numerically to describe the thermal distribution in the resistance spot welding system as a function of position and time. For each value in the time array, a heat transfer profile through the welding sheet is calculated as a piecewise function. The model is further executed with Python, which allows customized inputs of resistance spot welding parameters. Finally, the heat transfer model is simulated with COMSOL Multiphysics in the specific example of 1050 mild steel. Heat transfer module is applied to the proposed mathematical model, and simulation of temperature profile and thermal gradient of the welding zones are developed. The simulation further confirms the mathematical model and provides a demonstration that the temperature decreases through both the water-cooled welding tips and thermal diffusion to the surrounding metal sheets, leading to adjacent heat-affected zones. The model is intended for predicting the resistance spot welding nugget solidification process, as well as to help analyze the effects of welding parameters to achieve a weld nugget of optimal size.

Download Full-text