Analysis of Welding Process for Automotive Rear Cradle

2015 ◽  
Vol 1091 ◽  
pp. 97-101
Author(s):  
Hak Jae Seol ◽  
Kyoung Teak Lee ◽  
Chang Soo Park ◽  
Kwan Bong Yoo
Keyword(s):  
Residual Stress ◽  
Phase Transformation ◽  
Temperature Distribution ◽  
Transformation Temperature ◽  
Thermal Deformation ◽  
Welding Process ◽  
Phase Transformation Temperature ◽  
Side Member ◽  
Cross Member ◽  
Total Model

A rear cradle as one of the suspension system takes a role to connect a tie rod, suspension arm, transmissions and rubber bush. It consists of the side member and cross member which are joined by welding process. However, the rear cradle may be distorted due to thermal deformation during welding process, which cause dimensional tolerance problem when assembling. So, it is necessary to predict the thermal deformation and the optimal welding conditions should be suggested to reduce the dimensional tolerances. In this paper, MAG(metal active gas) welding process was applied in the simulation model using the SYSWELDR, commercial S/W for welding simulation. And then, It should be predicted on the results about the gap and thermal deformation of main cylinder and derived the phase transformation, temperature distribution, residual stress and thermal deformation of total model shape.

Capability of martensitic low transformation temperature welding consumables for increasing the fatigue strength of high strength steel joints

2020 ◽  
Vol 62 (9) ◽  
pp. 891-900
Author(s):  
Jonas Hensel ◽  
Arne Kromm ◽  
Thomas Nitschke-Pagel ◽  
Jonny Dixneit ◽  
Klaus Dilger
Keyword(s):  
Residual Stress ◽  
Phase Transformation ◽  
Fatigue Strength ◽  
High Strength Steel ◽  
Transformation Temperature ◽  
Fatigue Cracks ◽  
High Strength ◽  
Filler Material ◽  
Phase Transformation Temperature ◽  
Filler Materials

Abstract The use of low transformation temperature (LTT) filler materials represents a smart approach for increasing the fatigue strength of welded high strength steel structures apart from the usual procedures of post weld treatment. The main mechanism is based on the effect of the low start temperature of martensite formation on the stress already present during welding. Thus, compressive residual stress formed due to constrained volume expansion in connection with phase transformation become highly effective. Furthermore, the weld metal has a high hardness that can delay the formation of fatigue cracks but also leads to low toughness. Fundamental investigations on the weldability of an LTT filler material are presented in this work, including the characterization of the weld microstructure, its hardness, phase transformation temperature and mechanical properties. Special attention was applied to avoid imperfections in order to ensure a high weld quality for subsequent fatigue testing. Fatigue tests were conducted on the welded joints of the base materials S355J2 and S960QL using conventional filler materials as a comparison to the LTT filler. Butt joints were used with a variation in the weld type (DY-weld and V-weld). In addition, a component-like specimen (longitudinal stiffener) was investigated where the LTT filler material was applied as an additional layer. The joints were characterized with respect to residual stress, its stability during cyclic loading and microstructure. The results show that the application of LTT consumables leads to a significant increase in fatigue strength when basic design guidelines are followed. This enables a benefit from the lightweight design potential of high-strength steel grades.

scholarly journals The Effect of Martensitic Phase Transformation Dilation on Microstructure, Strain–Stress and Mechanical Properties for Welding of High-Strength Steel

Crystals ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 293 ◽  
Author(s):  
Xizhang Chen ◽  
Pengfei Wang ◽  
Qiuhong Pan ◽  
Sanbao Lin
Keyword(s):  
Residual Stress ◽  
Phase Transformation ◽  
Transformation Temperature ◽  
Weld Zone ◽  
Welding Process ◽  
Martensitic Phase ◽  
Martensitic Phase Transformation ◽  
Granular Bainite ◽  
Residual Tensile Stress ◽  
The Impact

The application of low transformation temperature (LTT) wire can effectively reduce residual stress, without the need for preheating before welding and heat treatment after welding. The mechanism reduces the martensitic transformation temperature, allowing the martensite volume expansion to offset some or all of the heat-shrinking, resulting in reduced residual stress during the welding process. In this paper, commercial ER110S-G welding wire and LTT wire with chemical composition Cr10Ni8MnMoCuTiVB were developed to solve the problem of stress concentration. The microstructure of the LTT joint is mainly composed of martensite and a small amount of residual austenite, while the microstructure of the ER110S-G joint is mainly composed of ferrite and a small amount of granular bainite. The micro-hardness and tensile strength of the LTT joint is higher than that of ER110S-G joint; however, the impact toughness of the LTT joint is not as good as that of the ER110S-G joint. The martensitic phase transformation of LTT starts at 212 °C and finishes at around 50 °C, and the expansion caused by phase transition is about 0.48%, which is much higher than that of the base metal (0.15%) and ER110S-G (0.18%). The residual tensile stress at the weld zone of the ER110S-G joint is 175.5 MPa, while the residual compressive stress at the weld zone of LTT joint is −257.6 MPa.

Phase Transformation Temperature of NiTi Alloy Sheet Examined by Lamb Wave

2011 ◽  
Vol 320 ◽  
pp. 359-362
Author(s):  
Kai Sheng Wang ◽  
Ru Hui He ◽  
Zhi Min Zhao
Keyword(s):  
Phase Transformation ◽  
Lamb Wave ◽  
Transformation Temperature ◽  
Lamb Waves ◽  
Niti Alloy ◽  
Alloy Sheet ◽  
Phase Transformation Temperature ◽  
Wave Method

In this study, the ultrasonic PZT transducers were used for exciting and receiving Lamb waves on NiTi alloy sheet. Lamb waves were measured when the temperature of the NiTi alloy changed. Analysis on frequency spectrums of the Lamb waves was also done. Some marked changes were observed in the dependence of the waveforms and the frequency spectrums of the Lamb waves versus temperature during phase transformation of NiTi alloy. The results show that phase transformation temperature of NiTi alloy sheet may be examined by Lamb wave method.

Continuous Cooling Phase Transformation Rules of High Nb X80 Pipeline Steel

2016 ◽  
Vol 850 ◽  
pp. 916-921
Author(s):  
Pei Pei Xia ◽  
Liu Qing Yang ◽  
Xiao Jiang Guo ◽  
Ye Zheng Li
Keyword(s):  
Phase Transformation ◽  
Cooling Rate ◽  
Acicular Ferrite ◽  
Thermal Deformation ◽  
Pipeline Steel ◽  
Phase Transformation Temperature ◽  
X80 Pipeline Steel ◽  
Continuous Cooling ◽  
Simulation Testing ◽  
Cooling Phase

The microstructural evolution of the high Nb X80 pipeline steel in Continuous Cooling Transformation (CCT) by Gleeble-3500HS thermal mechanical simulation testing system was studied, the corresponding CCT curves were drawn and the influence of some parameters such as deformation and cooling rate on microstructure of high Nb X80 pipeline steel was analyzed. The results show that as cooling rate increased, the phase transformation temperature of high Nb X80 steel decreased, with the microstructure transformation from ferrite-pearlite to acicular ferrite and bainite-ferrite. When cooling rate was between 20°C/s and 30°C/s, the microstructure was comparatively ideal acicular ferrite, thermal deformation accelerates phase transformation notably and made the dynamic CCT curves move upward and the initial temperature of phase transformation increase obviously. Meanwhile the thermal deformation refined acicular ferrite and extended the range of cooling rate accessible to acicular ferrite.

scholarly journals Influence of Heat Treatment on the Workability of Modified 9Cr-2W Steel with Higher B Content

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 904
Author(s):  
Hyeong Min Heo ◽  
Jun Hwan Kim ◽  
Sung Ho Kim ◽  
Jong Ryoul Kim ◽  
Won Jin Moon
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Phase Transformation ◽  
Transformation Temperature ◽  
Fracture Behavior ◽  
Rolling Process ◽  
Normal Direction ◽  
Phase Transformation Temperature ◽  
Treatment Conditions ◽  
Creep Characteristics

In this study, the effect of heat treatment on the fracture behavior of alloy B steel with boron (B) contents as high as 130 ppm was investigated. The Alloy B are derived from Gr.92 steel with outstanding creep characteristics. The amounts of minor alloying elements such as B, N, Nb, Ta, and C were optimized to achieve better mechanical properties at high temperatures. Hence, workability of the alloy B and Gr.92 were compared. An increase in the B content affected the phase transformation temperature and texture of the steel. The development of the {111}<uvw> components in γ-fibers depended on the austenite fraction of the steel after the phase transformation. An increase in the B content of the steel increased its α-to-γ phase transformation temperature, thus preventing the occurrence of sufficient transformation under the normalizing condition. Cracks occurred at the point of the elastic-to-plastic deformation transition in the normal direction during the rolling process, thereby resulting in failure. Therefore, it is necessary to avoid intermediate heat treatment conditions, in which γ-fibers do not fully develop, i.e., to avoid an imperfect normalization.

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