scholarly journals Investigation on Residual Compressive Distribution of High-Strength Steel for Bridges by Base Metal Hammer Impact Peening

2021 ◽  
Vol 2 (4) ◽  
pp. 932-941
Author(s):  
Yasuyuki Kurihara ◽  
Yoshihiro Sakino ◽  
Tomoharu Kato
Keyword(s):  
Residual Stress ◽  
Fatigue Strength ◽  
Base Metal ◽  
High Strength Steel ◽  
Plate Thickness ◽  
Base Material ◽  
Steel Structures ◽  
High Strength ◽  
Hammer Impact ◽  
Ordinary Steel

Various peening techniques have been used to improve the fatigue strength of steel structures. Among them, base metal impact hammer peening shows significant improvement in fatigue strength in ordinary steel, but the effect on high-strength steel has not been sufficiently studied. Accordingly, this study applied base material hammer impact peening to test specimens of 780 MPa grade high-strength steel (HT780) and 490 MPa grade ordinary steel (SM490), and the residual stress was measured and simulated. The experimental results clarified that a large compressive residual stress was introduced into the inner part of the plate thickness near the indentation in the high-strength steel, although the range of introduction of residual stress was equivalent in both the ordinary steel and high-strength steel.

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.

Identification of Weld Residual Stresses Using Diffraction Methods and their Effect on Fatigue Strength of High Strength Steels Welds

2013 ◽  
Vol 768-769 ◽  
pp. 668-674 ◽  
Author(s):  
Lubos Mraz ◽  
Leif Karlsson ◽  
Pavol Mikula ◽  
Miroslav Vrána
Keyword(s):  
Residual Stress ◽  
Fatigue Strength ◽  
High Strength Steel ◽  
Transformation Temperature ◽  
High Strength Steels ◽  
High Strength ◽  
Life Time ◽  
Filler Material ◽  
Phase Transformation Temperature ◽  
Steel Welds

It is well known that fatigue strength of welded joints does not depend on steel strength. Better fatigue strength of welded joints, e.g. longer life time of fatigue loaded weld structures, can be achieved with a smooth transition between the weld and the base material to minimize stress concentration. It has also been recognized that residual stresses play a critical role in the fatigue behaviour of welds. In the last decade an extensive research has been performed in order to increase the fatigue strength of high strength steel weldments. The martensite and bainite transformation start temperatures of weld metals have been shown to have a large effect on fatigue life time of high strength steel welds. This is of particular importance if the full potential of high strength steels is to be used in fatigue loaded constructions. A detailed investigation of the effect of phase transformation temperature on residual stress distribution in the vicinity high strength steel welds and its effect on fatigue life time has been performed. The transformation temperature of the weld metal was varied by changing the chemical composition of the filler material. Residual stress distributions have been measured by neutron as well as by X-ray diffraction and fatigue tests have been performed on the fillet welds. A strong effect of weld metal phase transformation temperature on residual stress level was observed. Fatigue strength increased approximately three times when an optimised low transformation temperature filler material was used in comparison to the application of conventional filler material.

Comparison of fatigue strength of post-weld improved high strength steel joints and notched base material specimens

2018 ◽  
Vol 13 (sup1) ◽  
pp. 47-55 ◽  
Author(s):  
Moritz Braun ◽  
Jan-Hendrik Grimm ◽  
Hasso Hoffmeister ◽  
Sören Ehlers ◽  
Wolfgang Fricke
Keyword(s):  
Fatigue Strength ◽  
High Strength Steel ◽  
Base Material ◽  
High Strength ◽  
Steel Joints

Increasing the fatigue strength of high-strength steel parts by repeated treatment with shot peening

2020 ◽  
pp. 79-82
Author(s):  
G.N. Kravchenko ◽  
K.G. Kravchenko
Keyword(s):  
Fatigue Strength ◽  
Shot Peening ◽  
High Strength Steel ◽  
High Strength ◽  
Resource Recovery ◽  
Repeated Treatment ◽  
Multiple Processing

The effectiveness of multiple hardening by shot peening of samples made of «30ХГСН2А» high-strength steel to increase their fatigue strength is experimentally established. Repeated hardenings allow not only to restore the original durability and even significantly increase it. Keywords fatigue strength, durability, resource recovery, multiple processing by shot peening, repeated hardening, high-strength steel. [email protected]

Study on the Local Buckling Behavior of Steel Equal Angle Members under Axial Compression with the Steel Strength Variation

2011 ◽  
Vol 374-377 ◽  
pp. 2430-2436
Author(s):  
Gang Shi ◽  
Zhao Liu ◽  
Yong Zhang ◽  
Yong Jiu Shi ◽  
Yuan Qing Wang
Keyword(s):  
Finite Element ◽  
Axial Compression ◽  
High Strength Steel ◽  
Local Buckling ◽  
Steel Structures ◽  
High Strength ◽  
Element Analysis ◽  
Equal Angle ◽  
Buckling Behavior ◽  
Steel Strength

High strength steel sections have been increasingly used in buildings and bridges, and steel angles have also been widely used in many steel structures, especially in transmission towers and long span trusses. However, high strength steel exhibits mechanical properties that are quite different from ordinary strength steel, and hence, the local buckling behavior of steel equal angle members under axial compression varies with the steel strength. However, there is a lack of research on the relationship of the local buckling behavior of steel equal angle members under axial compression with the steel strength. A finite element model is developed in this paper to analyze the local buckling behavior of steel equal angle members under axial compression, and study its relationship with the steel strength and the width-to-thickness ratio of the angle leg. The finite element analysis (FEA) results are compared with the corresponding design method in the American code AISC 360-05, which provides a reference for the related design.

Welding of Fe-Al Intermetallic Compound and Steel by SPS Technology

2012 ◽  
Vol 581-582 ◽  
pp. 582-585
Author(s):  
Guo Dong Zhang ◽  
Ya Dong Xiao ◽  
Nian Liu ◽  
Min Hong
Keyword(s):  
Intermetallic Compound ◽  
Base Metal ◽  
Heat Affected Zone ◽  
High Strength Steel ◽  
Chemical Potential ◽  
High Strength ◽  
Micro Hardness ◽  
Axial Pressure ◽  
Welding Joint ◽  
Short Period

The welding between Fe-Al intermetallic compound and high-strength steel was done via SPS technology. Microstructure, elements concentration and micro-hardness of welding joint were examined. The results indicated that there was no obvious welding heat-affected zone in both Fe-Al intermetallic compound and high-strength steel. The HAZ microstructures of high-strength steel were mainly martensite. In Fe-Al intermetallic compound, the grain size of heat-affected zone was larger than that of base metal and the density of heat-affected zone was lower than that of base metal. Besides, the grains of base metal had deformation phenomena. The welding joint had steady performance and the connection was reliable. Under the influence of chemical potential differences, unidirectional impulses discharge current and axial pressure, elements diffused perfectly in a short period of time.

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