Effect of Tempering Process on Residual Stress in Hot Rolled Low Carbon Martensite High-Strength Steel Strip

2013 ◽  
Vol 690-693 ◽  
pp. 222-226 ◽  
Author(s):  
Lin Sun ◽  
Zhi Yi Zhao ◽  
Xiao Zhen Yang ◽  
Run Dong Xue
Keyword(s):  
Residual Stress ◽  
Thermal Stress ◽  
Stress Distribution ◽  
High Strength Steel ◽  
Steel Strip ◽  
High Strength ◽  
Low Carbon ◽  
Width Direction ◽  
Hot Rolled ◽  
Carbon Martensite

Distribution of residual stress in hot rolled low carbon martensite high-strength steel strip was measured by means of blind-hole method in the steel before and after tempering. The hot rolled low carbon martensite high-strength steel strip was tempered at 450°C, 500°C, 550°C or 600°C. Before tempering, the value of the residual stress along the width direction is maximum at the edge, intermediate at the center, minimum at the 1/4 of the strip. The figure of the residual stress distribution along the width direction is like the shape of the letter M. Residual stress of the strip is reduced after tempering. When tempering at 450°C or 500°C, evolution of residual stress is caused by changes of thermal stress. Distribution of residual stress becomes gentle. With tempering temperature increasing, distribution of residual stress is reversed, because evolution of thermal stress and phase transition stress changes in different time.

scholarly journals Influence of Ti and Nb on the Strength–Ductility–Hole Expansion Ratio Balance of Hot-rolled Low-carbon High-strength Steel Sheets

2012 ◽  
Vol 52 (1) ◽  
pp. 151-157 ◽  
Author(s):  
Kyohei Kamibayashi ◽  
Yutaka Tanabe ◽  
Yoshito Takemoto ◽  
Ichirou Shimizu ◽  
Takehide Senuma
Keyword(s):  
High Strength Steel ◽  
High Strength ◽  
Expansion Ratio ◽  
Low Carbon ◽  
Hole Expansion ◽  
Steel Sheets ◽  
Hole Expansion Ratio ◽  
Hot Rolled

Investigations of Microstructure of Resistance Spot-Welded Joints Made of HSLA340 and DP600 Steels / Badanie Mikrostruktury Złączy Zgrzewanych Punktowo Ze Stali HSLA340 I DP600

2012 ◽  
Vol 57 (4) ◽  
pp. 1081-1086 ◽  
Author(s):  
A. Ignasiak ◽  
M. Korzeniowski ◽  
A. Ambroziak
Keyword(s):  
Welded Joints ◽  
High Strength Steel ◽  
Hsla Steel ◽  
High Strength ◽  
Dual Phase ◽  
Low Carbon ◽  
Spot Welds ◽  
Bainite Microstructure ◽  
Martensite Microstructure ◽  
Carbon Martensite

The paper presents results of metallographic investigations of spot welds made of high-strength steel HSLA340 and dual-phase DP600 steel. Low-carbon martensite microstructure was found in the weld nugget of HSLA steel. The DP600 steel shows martensite and bainite microstructure. For both steels, no carbides of microadditives were found because they dissolved in liquid nugget and could not precipitate again because of rapid heat abstraction. Moreover, no transcrystallisation was found in both steels, which proves good mixing of the materials within the weld.

scholarly journals Autofrettage of component-like ultra high Strength Steel Specimens with intersecting Holes

2021 ◽  
Vol 349 ◽  
pp. 04004
Author(s):  
Carl Fällgren ◽  
Thomas Beier ◽  
Michael Vormwald ◽  
Andreas Kleemann
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Stress Distribution ◽  
Crack Initiation ◽  
Crack Propagation ◽  
High Strength Steel ◽  
High Strength ◽  
Crack Arrest ◽  
Residual Stress Distribution ◽  
Ultra High Strength Steel

This work is primarily concerned with the fatigue life of high-pressure-bearing components with intersecting holes, typically used in Diesel engine fuel injection systems. The investigation focuses on specimens with intersecting holes that have undergone the process of Autofrettage (single mechanical overload), which is typically used to extend the fatigue life of components loaded by cyclic internal pressure. The resulting residual stress distribution thus influences the fatigue failure and especially the crack propagation behaviour of the components. In previous works, results showed that besides crack initiation, crack arrest behaviour has to be taken into account when calculating fatigue lives of autofrettaged specimens as the endurance limit is otherwise underestimated. In order to achieve reliable results, material testing with samples made of the ultra high strength steel W360 was performed. The resulting test data were used to simulate the Autofrettage process with finite-element analysis. Calculated residual stress distributions were used to determine at which levels of subsequent cyclic loading crack initiation would occur. For predicted crack initiation, the simulated residual stress distribution was used to investigate the crack propagation behaviour with fracture mechanics based approaches of different complexity in order to identify possible crack arrest or crack propagation. Calculated results were compared to experimental test data from component-like specimens. The comparison showed that the fracture mechanics based approaches are capable of describing the crack arrest and propagation behaviour reliably.

Martensitic Transformation in a Low-Alloy Ultra-High-Strength Steel

2011 ◽  
Vol 295-297 ◽  
pp. 1470-1473 ◽  
Author(s):  
Zhi Xia Qiao ◽  
Dan Tian Zhang ◽  
Yong Chang Liu ◽  
Ze Sheng Yan
Keyword(s):  
Martensitic Transformation ◽  
High Strength Steel ◽  
Lath Martensite ◽  
High Strength ◽  
Transformation Rate ◽  
Low Carbon ◽  
High Carbon ◽  
Process Characteristics ◽  
Ultra High Strength Steel ◽  
Carbon Martensite

Martensitic transformation is the most important phase transformation strengthening the 30CrNi3MoV ultra-high-strength steel during heat treatment process. Characteristics of the martensitic transformation in the 30CrNi3MoV steel were investigated by means of dilatometric measurements and microstructural observations. The results showed that the starting and finishing martensitic transformation temperatures of the 30CrNi3MoV explored steel are 317°C and 167°C respectively, which are hardly influenced by the cooling rate from austenite region. Such a wide temperature range of martensitic transformation in the 30CrNi3MoV steel results into the diversity of martensite microstructures. The microstructures in all the quenched 30CrNi3MoV samples are composed of mixture of lath and acicular martensite, corresponding to low-carbon and high-carbon martensite respectively. The transformation rate of acicular martensite is much slower than that of lath martensite, which can be attributed to the stabilization of the rest high-carbon austenite after the formation of lath martensite.

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