Induction assisted laser welding of advanced high strength steels to increase the formability of welded automotive body structures

Author(s):  
Axel Jahn ◽  
Berndt Brenner ◽  
Eckhard Beyer
Author(s):  
O¨mer Necati Cora ◽  
Muammer Koc¸

Newer sheet alloys (such as Al, Mg, and advanced high strength steels) are considered for automotive body panels and structural parts to achieve lightweight construction. However, in addition to issues with their limited formability and high springback, tribological conditions due to increased surface hardness and higher work hardening effect necessitate the use of improved alternative die materials, coatings, lubricants to minimize the wear-related issues in stamping of such lightweight materials. This study aims to investigate and compare the wear performances of seven (7) different die materials (AISI D2, Vanadis 4, Vancron 40, K340 ISODUR, Caldie, Carmo, 0050A) using a newly developed wear testing method and device. We used DP600 sheets in the tests. Our results showed that almost all of the recently developed specially-alloyed die materials demonstrated higher wear resistance performance when compared with the performance of AISI D2 die material.


Author(s):  
Ramakrishna Koganti ◽  
Sergio Angotti ◽  
Armando Joaquin ◽  
Cindy Jiang

There has been a substantial increase in the use of advanced high strength steel in automotive structures in the last few years. The usage of these materials is projected to grow significantly in the next 5–10 years with new safety and fuel economy regulations. Advanced High Strength Steels (AHSS) are getting popular with superior mechanical properties and weight advantages compared to mild steel materials. These new materials have significant manufacturing challenges, particularly for welding and stamping. Proper understanding of the weldability of these materials is critical for successful application in future vehicle programs. Due to high strength nature of AHSS materials, higher weld forces and longer weld times are needed to weld AHSS materials. In this paper, weld lobe development for DP600, and DP780 steels are discussed. DP600 steels were joined with two different weld equipments and three different electrodes and their influence on mechanical properties are discussed. Development work on the effect of weld tips on button size, and shrinkage voids due to different welding variables is discussed. DP780 EG steel (1.0 mm) is also joined to itself. The weld lobes, mechanical properties (tensile shear and cross tension), cross-section examination, and microhardness of 1.0 mm DP780 EG to 1.0 mm DP780 EG weld joint results are discussed.


2013 ◽  
Vol 814 ◽  
pp. 207-213 ◽  
Author(s):  
Aurel Valentin Bîrdeanu ◽  
Cristian Ciucă ◽  
Alexandru Joni

The need of cost and weight reduction trend present in the automotive industry lead to the implementation into automotive sector of new materials categorized as Advanced High Strength Steels (AHSS). The use of these materials requires the development of appropriate joining technologies, e.g. pulsed laser welding. The paper presents the results of the development of overlap joints realized by pulsed laser welding technologies of Zn coated AHSS. The statistical influence of the main process parameters was investigated by means of factorial experiment design weighted towards the shear strength results. The influence of laser pulse peak power, the joint gap, the travel speed and the position of the focal point were investigated for three types of AHSS with different thicknesses. The results reveled that the base material thickness influences the importance of the investigated process parameters with impact onto the maximum obtainable shear strength values. Thus, with the thinnest plates, the travel speed is the most important process parameters then the joint gap starts to have also an important role, and for the thicker plates the joint gap becomes the most important influence factor – a phenomena which can be related to the Zn vapour expulsion.


2010 ◽  
Vol 146-147 ◽  
pp. 1265-1269
Author(s):  
Wen Jiao Dan ◽  
Wei Gang Zhang ◽  
Shu Hui Li

As an advanced high strength steels, transformation-induced plasticity (TRIP) steel has obtained more and more attentions in automotive body components forming. The TRIP effect of this steel can improve the strength of the material, which results in the spring-back angle is different with that without TRIP effect. In this paper, the spring-back process of U-channel stamping with TRIP effect is studied by deformation energy method, which is based on a constitutive model accompanying strain-induced transformation in strain rate condition. The results have shown that martensite volume fraction distribution in key parts is related to the deformation energy of material, which induces the spring-back angle higher than those without TRIP.


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