Comparison of RSW technologies on DP steels with modified instrumented Charpy impact test (original) (raw)
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Welding in the World, 2012
N. den Uijl, T. Okada, T. Moolevliet, A. Mennes, E. van der Aa, M. Uchihara, S. Smith, H. Nishibata, K. Fukui: IIW-2162-11 (III-1573-10) Performance of resistance spot welded joints in advanced high strength steel in static and dynamic tensile tests. Welding in the World 7/8, 2012. The performance of resistance spot-welded joints in advanced high-strength steel sheets is critical for the application of these materials in safety-critical areas. To be able to predict the performance of such joints from available material data would be of great benefit to the automotive industry. This report starts with a review of literature about various aspects of spot weld performance in advanced high-strength steels. It then describes experimental work whereby a set of resistance spot-welded joints in various advanced high-strength steels was tested in lap shear and peel-type tensile testing. Testing was done both statically and dynamically. The steel sheet materials varied in microstructural and chemical compositions, strength and thickness. The goal of the tests was to investigate possible relations between material characteristics and performance of the welded joints. Therefore, the experimental results are related to several material parameters, i.e., sheet thickness, base metal yield and tensile strength, carbon content and various Carbon Equivalent numbers.
Analysis of SA 387 Gr. 91 welded joints crack resistance under static and impact load
Procedia Structural Integrity, 2021
This paper presents the results of experimental testing of crack resistance of specimens taken from a welded plate made of steel SA-387 Gr. 91, while taking into account different filler materials and welding procedures that were used. This type of steels is typically used in pressure vessels, pipelines and gas installations in the chemical and petrochemical industry, as well as in thermal installations. Since it is operating under extreme conditions, which include elevated temperatures and/or corrosion, the mechanical properties of SA-387 Gr. 91 will deteriorate over time, especially its welded joints. For this reason, it is very important to thoroughly analyse the behaviour of welded joints, taking into account the possibility of cracks initiating in any of the three welded joint regions, the parent material (PM), the weld metal (WM) and the heat affected zone (HAZ). This can be achieved by determining the total impact energy of Charpy specimens with V-2 notches in each of the three regions, along with their components, crack initiation and crack propagation energy, as well as by measuring the fracture toughness.
IMPACT TOUGHNESS OF HIGH-STRENGTH LOW-ALLOY STEEL WELDED JOINTS
Applied Engineering Letters, 2018
Impact toughness of samples with three different relative positions of V-notch and multipass V-butt welded joint at high-strength low-alloy steel S690 are considered in this paper. The aim of this paper is to analyze the influence of material degradation due to welding to impact toughness of samples made of considered steel. Impact toughness was analyzed by experimental approach objected to including as many influential factors as it is possible. The main objective of impact toughness testing is to evaluate the influence of welding to overall load capacity and stability of welded mechanical construction made of high-strength low-alloy steels. Fully understanding of transformation processes provoked by welding of high-strength low-alloy steels and impact toughness testing as resulting property of those processes are crucial to perform integrity, safety and reliability analysis. This paper pointed out the necessity of analyzing the welded constructions on different dimension levels. Further investigations in this area have to be a continued through more quantitative analysis of welded joints which will, established precise analytical model of zones of welded joints, and furthermore, in involvement with adequate software, a complete evaluation of the experimentally obtained results. As experimentally obtained results of impact toughness that correlate to microstructure and microhardness distribution implicated that development of those steels must be followed with improving weld processes and development, adjusting and modification of the design. ARTICLE HISTORY
Static and impact crack properties of a high-strength steel welded joint
International Journal of Pressure Vessels and Piping, 2007
In order to gain the benefits of weldable high-strength steels in pressurized equipment applications, satisfactory toughness and crack properties of the welded joint, both in the weld metal and the heat-affected -zone (HAZ), are required. Experimental investigations of toughness and crack resistance parameters through static and impact tests of a high-strength, low-alloy steel (HSLA) with a nominal yield strength of 700 MPa and its welded joint, were performed on Charpy-sized specimens, V-notched and pre-cracked, of the parent metal, weld metal and HAZ. The selected electrode produced slight undermatching and enabled the welded joints to be manufactured without cold cracks. The impact energy and its parts responsible for crack initiation and propagation were determined by toughness evaluation. Crack sensitivity, defined as the ratio of the impact energy for V-notched and for pre-cracked specimens, enabled a comparison of the homogeneous microstructure of the parent metal and the weld metal, and of the heterogeneous microstructure of the heat-affected-zone (HAZ), which indicated a better crack toughness behaviour of the HAZ. The results obtained showed that the toughness and crack resistance of the weld metal were significantly lower than those of the parent metal and the HAZ. The fracture mechanics parameters, J Ic integral, and plane strain fracture toughness, K Ic , as well as J resistance curves expressed the degradation less. r
Performance of Tensile Tested Resistance Spot and Laser Welded Joints at Various Angles
Welding in the World, 2012
N. den Uijl, F. Azakane, S. Kilic, V. Docter, B. Neelis, C. Goos & E. van der Aa: IIW-2327-11 Performance of tensile tested resistance spot and laser welded joints at various angles. Welding in the World 11/12 2012. The performance of welded joints is usually evaluated using coupon tests under either normal or shear tensile loading. The actual loading of these joints in an automotive structure may be quite different, especially concerning the angle in which the load is applied. In this report an overview is given of published results on the performance of welded joints in automotive applications. Next the results from a series of resistance spot and laser welded joints in different steel sheet materials (HSLA and DP of varying thickness) subjected to tensile tests under varying loading angles are presented. The focus is on resistance spot welded joints, but the results are compared to similar tests performed with laser welded joints. The performance of the welded joints in terms of failure mode and strength are analysed, and the possible implications for automotive applications are discussed. Finally some work using finite element simulations is presented. Here the characteristics of the base material and welded joints of different grades of materials are evaluated to investigate the differences in performance in tensile testing. It is concluded that the thickness of the materials is the main parameter determining the failure characteristics of materials. The grade (HSLA or DP) is less of a factor determining failure mode. The fact that joints in DP steel perform as well as HSLA steels allows designers and engineers to use the advanced high strength steel without having to worry about unpredictable failure behaviour leading to decreased performance for safety critical applications.
Influence of Welding Parameters on the Quality of Resistance Spot Welded Joints of DP600 Steels
Key Engineering Materials, 2014
Advanced high-strength dual-phase steel was developed specifically for automotive industry in order to benefit from its excellent formability and great crash absorption ability in comparison with conventional AHSS. Resistance spot welding is the dominant and effective method of joining metal sheets in automobile industry. After spot welding, important changes occur in mechanical and metallurgical properties of the spot welded areas and heat affected zones. The investigation into these changes is very important for safety, which depends on the strength of the welded joints. Weldability of the DP steel is one of the key factors governing its application in automotive industry. The influence of the primary welding parameters, especially welding current, on the weld quality was investigated by testing microhardness and tensile shear load bearing capacity of resistance spot welds of DP600 steel sheets.
Toughness of welded stainless steels sheets for automotive industry
Journal of achievements in materials and manufacturing engineering, 2011
Purpose: In the automotive industry, more and more it is compulsory to develop new grades of stainless steels, such as high resistant Martensitic Stainless Steels (MA-SS) and Ferritic Stainless Steels (FSS) in order to realise certain or many complex deep drawn pieces. For these grades, resistance spot welding (RSW) is the most widespread process used largely for many parts of the car body in the automotive industry. This paper aims to characterise mechanical behaviour (toughness) of the different steel grades under dynamic test conditions. Design/methodology/approach: A special crash test device is used in different temperatures and the simulated crash tests are performed at a constant speed of 5.52 m/s. Findings: The specimen is submitted to impact tensile test at different temperatures. According to testing temperature, fracture mode varies: At low temperatures, brittle fracture occurs: due to stress concentration, fracture always occurs in the notched section. At high temperatur...
Simulation and Validation of Welded Joints of High Strength Steel Sheets
2014
In this study the residual stress distributions of spot welded advanced high strength steel (AHSS) sheets are examined. Resistance spot welded and gas tungsten arc spot welded DP 600 specimens are manufactured and tested for residual stresses. In the case of resistance spot welding (RSW) both single-pulse and two-pulse current are used. These measurements are utilized to validate coupled electrical-thermal-mechanical Finite Element Analysis (FEA) using MSC.Marc software. The analysis is performed on a two-dimensional axisymmetric finite element model. Different mechanisms occur during the welding e.g. electrode displacement, deformation of the weld nugget and distribution of the contact pressure at both sides and they are all taken into consideration. The cross-section macrostructures of the welded specimens are examined to compare the weld nugget and HAZ sizes to the predicted values. The simulated weld nugget sizes are in good agreement with the experimental results. The validated...
Mechanical Properties of Resistance Spot Welded Joints of Mild Steel Under Static Load
2015
This paper emphasizes the mechanical properties of resistance spot welded (RSW) joints of mild steel under static loading conditions. In this study, cold rolled mild steel sheets of 2 mm thickness are used. For failure analysis of RSW of mild steel joints, tensile-shear tests of the joints are conducted. The tensile-shear test is the most commonly used test for evaluating the mechanical behaviors of the spot welded joint. As the common use of the spot welded joints in automobile and aerospace industries, the mechanical behaviors of the spot welded joints under such loading conditions are an important scope to be studied. The experimental result show that the RSW joints formed under 13 KA and 4 kN can sustain 7.33 kN tensile-shear load before failure. The observation of failed specimens show that the RSW joint was failed either interfacial or plug failure mode depending on the welding parameters and welding quality. The Vickers hardness result shows that the hardness values in the we...
Revista de Metalurgia
The purpose of this study is to determine fracture toughness of Resistance Spot Welded (RSW) Dual Phase (DP) steels. RSW of galvanized and ungalvanized DP 450 steel sheets was carried out on spot welding machine. Fracture toughness of RSW joints of galvanized and ungalvanized DP 450 steel sheets was calculated from tensile-shear tests. New empirical equations were developed using Least Squares Method (LSM) between energy release rate, fracture toughness and critical crack size depending on the relationship between hardness and fracture toughness values. Results indicated that fracture toughness of joints welded by using RSW increased exponentially while the hardness decreased. In addition, fracture toughness and energy release rate of RSW galvanized DP 450 steel sheets were lower compared to RSW ungalvanized DP 450 steel sheets which had approximately the same hardness.