DYNAMIC MATERIAL PROPERTIES OF THE HEAT-AFFECTED ZONE (HAZ) IN RESISTANCE SPOT WELDING

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5800-5806 ◽  
Author(s):  
JI-WOONG HA ◽  
JUNG-HAN SONG ◽  
HOON HUH ◽  
JI-HO LIM ◽  
SUNG-HO PARK
Keyword(s):  
Heat Affected Zone ◽  
Material Properties ◽  
High Speed ◽  
Testing Machine ◽  
Tensile Tests ◽  
Strain Rates ◽  
Element Analysis ◽  
Resistance Spot ◽  
Dynamic Material Properties ◽  
Spot Welded

This paper is concerned with a methodology to identify the dynamic material properties of the heat-affected zone (HAZ) near the base metal in a resistance spot weld process at various strain rates. In order to obtain the dynamic material properties of the HAZ in the spot-welded steel sheet, specimens are prepared to have similar material properties, hardness and microstructure to the actual HAZ. Such thermally simulated specimens are fabricated with the material thermal cycle simulator (MTCS) and compared with the real one for the hardness and microstructure. Dynamic tensile tests are then conducted with a high speed material testing machine. Stress–strain curves of the thermally simulated HAZ are obtained at various strain rates ranged from 0.001/sec to 100/sec. Obtained material properties are applied to the finite element analysis of the spot-welded tensile-shear specimen in order to verify validity of the proposed testing methodology and obtained results. Analysis results demonstrate that the material properties obtained are appropriate for the FE analysis of spot-welded specimens.

scholarly journals Finite Element-Based Simulation of Cooling Rate on the Material Properties of an Automobile Silent Block

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Burak Öztürk ◽  
Fuat Kara
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Cooling Rate ◽  
Material Properties ◽  
High Speed ◽  
Tensile Tests ◽  
Isothermal Transformation ◽  
Element Analysis ◽  
Front Suspension ◽  
Safety Coefficient

The aluminum silent block is the part that connects the front suspension mounting and the road wheels. These products are used in high-speed cars and are subject to high engineering stresses. Over time, fractures occur in the connection part of these products due to insufficient strength. These problems are related to production metallurgy, which led to the concept of this study. During mass production, these parts are manufactured using the aluminum extrusion method. In this study, a rapid cooling process using water was applied, with the aim of improving the mechanical properties of the connecting part exposed to high dynamic loads. Samples were taken from the regions of these products which differed in thickness and width, and microhardness and tensile tests were performed for each region. The effects of both the extrusion cooling rate and the regional flash cooling on the material properties were then characterized. As a result of the isothermal transformation, the grain size in the microstructure of the material had shrunk. According to the findings, in this type of production, an average increase in strength of 25% was observed in the parts of the material subjected to maximum stress. The stress and safety coefficient values were found using finite element analysis, and curves were then drawn showing the differences in the safety coefficient values from the different points. As a result of cooperation between university and industry, the material and mechanical properties of an automobile part were improved in this study. This research has shown that, in terms of the accuracy of the results, it is very important to consider the variations in different regions of the product when defining the mechanical properties of any material produced by applying casting, heat treatment, and plastic forming methods.

An Experimental Study of Mechanical Behavior of Resistance Spot Welded Aluminum 6061-T6 Joints

2010 ◽  
Author(s):  
R. S. Florea ◽  
K. N. Solanki ◽  
Y. Hammi ◽  
D. J. Bammann ◽  
M. P. Castanier
Keyword(s):  
Experimental Study ◽  
Mechanical Behavior ◽  
Tensile Tests ◽  
Welding Parameters ◽  
Material Anisotropy ◽  
Element Analysis ◽  
Resistance Spot ◽  
Lap Shear ◽  
Failure Loads ◽  
Spot Welded

In this study, the mechanical behavior, joint characterization and process sensitivity of aluminum 6061-T6 alloy Resistance Spot Welded (RSW) joints are investigated. Tensile tests were conducted on single weld lap-shear coupons until failure in order to determine the optimum welding parameters. Welding currents, forces and times have been investigated to establish the correlation between failure loads and nugget sizes. The experimental and preliminary finite element analysis (FEA) results indicate that failure loads and nugget sizes are strongly dependent upon welding parameters and the material anisotropy.

scholarly journals The Performance of CR180IF and DP600 Laser Welded Steel Sheets under Different Strain Rates

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1553
Author(s):  
Mária Mihaliková ◽  
Kristína Zgodavová ◽  
Peter Bober ◽  
Anna Špegárová
Keyword(s):  
Sheet Steel ◽  
Testing Machine ◽  
Dynamic Test ◽  
Tensile Tests ◽  
Joint Surface ◽  
Strain Rates ◽  
Interstitial Free ◽  
Welded Steel ◽  
Steel Sheets ◽  
Static Tensile

The presented research background is a car body manufacturer’s request to test the car body’s components welded from dissimilar steel sheets. In view of the vehicle crew’s protection, it is necessary to study the static and dynamic behavior of welded steels. Therefore, the influence of laser welding on the mechanical and dynamical properties, microstructure, microhardness, and welded joint surface roughness of interstitial free CR180IF and dual-phase DP600 steels were investigated. Static tensile tests were carried out by using testing machine Zwick 1387, and dynamic test used rotary hammer machine RSO. Sheet steel was tested at different strain rates ranging from 10−3 to 103 s−1. The laser welds’ microstructure and microhardness were evaluated in the base metal, heat-affected zone, and fusion zone. The comprehensive analysis also included chemical analysis, fracture surface analysis, and roughness measurement. The research results showed that the strain rate had an influence on the mechanical properties of base materials and welded joints. The dynamic loading increases the yield stress more than the ultimate tensile strength for the monitored steels, while the most significant increase was recorded for the welded material.

Damage Length Predictor for High-Speed Craft

1999 ◽  
Vol 36 (04) ◽  
pp. 203-210
Author(s):  
Steven P. McGee ◽  
Armin Troesch ◽  
Nickolas Vlahopoulos
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Material Properties ◽  
High Speed ◽  
Historical Data ◽  
Element Analysis ◽  
Damage Prediction ◽  
Structural Layout ◽  
Vessel Speed ◽  
Indenter Geometry

In 1994 the International Maritime Organization adopted the Code of Safety for High-Speed Craft (HSC Code). After two years of use, several shortfalls were found, one being the damage length predictor, which is based on traditional steel, mono-hulled vessels. Other damage predictors were developed based on historical data, but they do not account for variables such as aluminum or fiberglass construction, transverse members, indenter geometry variation, or for the case where the vessel comes to rest on the grounding object. This paper proposes a damage prediction model based on material properties, structural layout, grounding object geometry, and vessel speed. The model incorporates four grounding mechanisms: plate cutting, plate tearing, crushing of plate behind transverse members, and transverse member failure. The method is used to determine the resistance energy, compared to the kinetic energy, of the vessel, to determine an effective damage length. Finite-element analysis was used to model the failure of both aluminum and steel transverse members with significant differences in the results. It was found that the transverse members provided the majority of the resistance energy in one grounding mechanism and negligible resistance energy in another.

Comparative Study on Hydrogen Embrittlement Susceptibility in Heat-Affected Zone of TP321 Stainless Steel

2020 ◽  
Vol 993 ◽  
pp. 568-574
Author(s):  
Xiu Qing Xu ◽  
Jing Niu ◽  
Cheng Zheng Li ◽  
Hang Juan Huang ◽  
Cheng Xian Yin
Keyword(s):  
Stainless Steel ◽  
Heat Affected Zone ◽  
Testing Machine ◽  
Tensile Tests ◽  
Tensile Specimen ◽  
Excellent Performance ◽  
Creep Stress ◽  
Δ Ferrite ◽  
Electrolytic Hydrogen ◽  
Reduction Of Area

TP321 stainless steel is widely used in hydrogenation refining pipes owing to its excellent performance of creep stress resistance and high-temperature resistance. In this study, thermal simulation tests were carried out on the welding heat-affected zone (HAZ) of TP321 stainless steel at temperatures of 1300 °C, 1100 °C, and 850°C using a Gleeble 3800 testing machine. Slow strain tensile tests were conducted under the condition of electrolytic hydrogen charging (EHC) and the metallographic microstructure of cracks as well as the morphology of fractures were analyzed in detail. The result shows that hydrogen can change the fracture mode of tensile specimen and the cracks initiated from and near the specimen surface after EHC. Hydrogen significantly decreases the plastic deformation capability of HAZ in TP321 stainless steel. The reduction of area after the fracture decreases by 58%, 41%, and 45% for HAZ at 1300 °C, 1100 °C, and 850 °C, respectively. The existence of δ ferrite was considered to be the main reason for the aggravation of hydrogen-induced plasticity loss.

1106 Tensile Tests on Steels and Aluminum alloys in a Wide Range of Strain Rates by High Speed Material Testing System with Sensing Block

2000 ◽  
Vol 2000.75 (0) ◽  
pp. _11-11_-_11-12_
Author(s):  
Takeshige MACHIGAKI ◽  
Yoshitaka ASHIDA ◽  
Koji MIMURA ◽  
Tsutomu UMEDA ◽  
Shinji TANIMURA
Keyword(s):  
Aluminum Alloys ◽  
High Speed ◽  
Tensile Tests ◽  
Material Testing ◽  
Testing System ◽  
Strain Rates ◽  
Wide Range

A study on heat affected zone softening in resistance spot welded dual phase steel by nanoindentation

2009 ◽  
Vol 45 (6) ◽  
pp. 1638-1647 ◽  
Author(s):  
Victor Hugo Baltazar Hernandez ◽  
Sushanta Kumar Panda ◽  
Yasuaki Okita ◽  
Norman Y. Zhou
Keyword(s):  
Heat Affected Zone ◽  
Dual Phase Steel ◽  
Dual Phase ◽  
Resistance Spot ◽  
Heat Affected Zone Softening ◽  
Spot Welded
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