High strength, low carbon, Cu containing steel plates with tailored microstructure and low yield ratio

2015 ◽  
Vol 42 (8) ◽  
pp. 608-617 ◽  
Author(s):  
B. G. Cheng ◽  
M. Luo ◽  
D. S. Liu
Keyword(s):  
High Strength ◽  
Yield Ratio ◽  
Steel Plates ◽  
Low Carbon

Study on the Cooling Process of Low Yield Ratio 590-780MPa Grade Steel Plates for High-Rise Buildings

2011 ◽  
Vol 194-196 ◽  
pp. 292-295 ◽  
Author(s):  
Jian Kang ◽  
Zhao Dong Wang ◽  
Guo Dong Wang
Keyword(s):  
Mechanical Properties ◽  
Structural Steel ◽  
High Strength ◽  
Ferrite Matrix ◽  
Yield Ratio ◽  
Steel Plates ◽  
Air Cooling ◽  
Soft Phase ◽  
Cooling Temperature ◽  
Ultra Fast Cooling

To develop 590/780MPa grade low yield ratio structural steel, the effects of ultra fast cooling (UFC) new process on microstructure and mechanical properties were investigated. The results showed that the low yield ratio and high strength can be obtained by proper phase compositions including relative soft phase and hard phase. For the process of UFC + air cooling, when UFC final cooling temperature was 521°C, 22.5% M-A second hard phases were distributed on bainite ferrite matrix in steel No.A2. The mechanical properties can meet requirement of 590MPa grade low yield ratio structural steel. For the process of air cooling + UFC, when UFC initial cooling temperature was 781°C, the multiphase composed of 28.3% ferrite and other bainite / martensite lath structure can ensure the high strength and low yield ratio of steel No.B1. And performance indexes can meet the requirement of 780MPa grade low yield ratio structural steel.

On the Microstructure of Plate Steels for API-5L X120 Applications

2012 ◽  
Vol 706-709 ◽  
pp. 17-23 ◽  
Author(s):  
C. Isaac Garcia ◽  
Ming Jian Hua ◽  
X. Liang ◽  
P. Suikannen ◽  
Anthony J. DeArdo
Keyword(s):  
Hsla Steel ◽  
High Strength ◽  
Steel Plates ◽  
Low Carbon ◽  
Austenite Grain Size ◽  
Direct Quenching ◽  
Prior Austenite Grain Size ◽  
Optical Examination ◽  
Very High

The very high strength now achievable in low carbon HSLA steel plates is caused by the formation of bainite or martensite during the post-hot rolling cooling in interrupted direct quenching. Modern electron optical examination, especially FEG-SEM, has allowed the microstructural features such as packet, block and lath dimensions and crystallography to be quantitatively determined. Several recent studies have attempted to relate the strength and toughness to these features, with limited success. However, one observation is clear, these microstructural features scale with the prior-austenite grain size and state of recrystallization. The role of microalloying, beyond grain refinement, remains inconclusive. This paper will discuss these microstructures and suggest possible ways of further refining them.

Refinement of Cementite in High Strength Steel Plates by Rapid Heating and Tempering

2007 ◽  
Vol 539-543 ◽  
pp. 4720-4725 ◽  
Author(s):  
A. Nagao ◽  
K. Hayashi ◽  
K. Oi ◽  
S. Mitao ◽  
N. Shikanai
Keyword(s):  
Rapid Heating ◽  
High Strength ◽  
Average Diameter ◽  
Carbon Steels ◽  
Steel Plates ◽  
Heating Process ◽  
Low Carbon ◽  
Precipitation Behavior ◽  
Heating Rates ◽  
Extraction Replica

The precipitation behavior of cementite in low carbon steels at various heating rates from 0.3 to 100 K/s has been studied using a high-frequency induction heating apparatus. The materials used in this study were steel platesfor welded structures: 610 and 780 MPa class steel plates with a mixed microstructure of bainite and martensite.Cementite was observed using a carbon extraction replica method and the hardness and toughness were also examined. When heated at the conventional slow rate of 0.3 K/s, relatively large cementite particles with an average diameter of 72 nm precipitated at the lath boundaries, whereas when heated at a rapid rate over 3.0 K/s, cementite precipitated both within the laths and at the lath boundaries, and the cementite was refined down to an average diameter of 54 nm. With such refinement of the cementite, the toughness was improved. On the other hand, the hardness was irrespective of the heating rate and was dependent on the tempering parameter. TEM observations of the cementite precipitation behavior during the rapid heating process revealed that cementite begins to precipitate at the lath boundaries at about 773 K and within the laths at about 873 K. It is concluded that rapid heating especially from 773 to 873 K contributes to the cementite refinement and consequently the improvement in toughness. The effect of alloying elements such as chromium, molybdenum or silicon on the cementite growth during the rapid heating and tempering treatment is also discussed.

As-Rolled High-Strength Plate Grades for Navy Shipbuilding Applications

1989 ◽  
Vol 5 (03) ◽  
pp. 200-205
Author(s):  
J. G. Speer ◽  
S. S. Hansen
Keyword(s):  
Microalloyed Steel ◽  
Hsla Steel ◽  
High Strength ◽  
Steel Plates ◽  
Low Carbon ◽  
Heat Treated

As-rolled high-strength, low-alloy (HSLA) steel plates offer a number of benefits compared with heat-treated plates, and this paper discusses laboratory and production experiments which have been conducted to develop as-rolled grades for high-strength Navy shipbuilding applications (for example, HSLA-65 and HSLA-80). A low-carbon niobium/vanadium microalloyed steel is shown to offer favorable combinations of strength, toughness, and weldability. The results indicate that an as-rolled grade which meets the current HSLA-80 strength and impact requirements can be produced in thicknesses up to approximately 19 mm (3/1 in.); HSLA-65 plates can be produced up to about 51 mm (2 in.) thick. This grade is generally weldable without preheat using HY-80 consumables.

Peculiarities of Weld Seams and Adjacent Zones Structures Formed in Process of Explosive Welding of Sheet Steel Plates

2011 ◽  
Vol 673 ◽  
pp. 95-100 ◽  
Author(s):  
Ivan A. Bataev ◽  
Anatoly Bataev ◽  
Vjacheslav I. Mali ◽  
Maksim A. Esikov ◽  
Vladimir A. Bataev
Keyword(s):  
Explosive Welding ◽  
Fatigue Cracks ◽  
Sheet Steel ◽  
Low Carbon Steel ◽  
High Strength ◽  
Strength Properties ◽  
Steel Plates ◽  
Maximum Temperature ◽  
Low Carbon ◽  
Transmission Electron

The structure and mechanical properties of the laminates produced by explosive welding of low carbon steel were investigated. The maximum number of layers in the composites was 21. It was shown that the structure of the composite is not uniform across the thickness of the layers and along the boundaries in the shape of the wave. Transmission electron microscopy revealed that the sizes of the grain-subgrain clusters forming in the weld adjacent zones are about 100…400 nm. The maximum temperature was reached in the areas of the vortices. High-strength martensite was formed in these zones in the process of cooling. The strength properties and toughness of the com-posite is almost 2 times higher compared with the properties of the original plates. It was shown that the boundaries of welds are the barriers inhibiting the development of fatigue cracks.

Effects of Rolling Process on Microstructure and Yield Ratio in a High Strength Building Steel Plate

2013 ◽  
Vol 631-632 ◽  
pp. 637-642
Author(s):  
Tao Xiong ◽  
Hong Wei Yu ◽  
Shi Sen Wang ◽  
Han Xiong Dong ◽  
De Fa Li
Keyword(s):  
Tensile Strength ◽  
Steel Plate ◽  
Interlamellar Spacing ◽  
High Strength ◽  
Rolling Process ◽  
Area Ratio ◽  
Yield Ratio ◽  
Steel Plates ◽  
Refined Grains ◽  
Iron And Steel

The microstructures have been investigated in steel plates with different rolling processes to find the reasons of yield ratio overseted standard in few high strength building steel plates produced in Echeng Iron and Steel Corporation. The effects of rolling path, rolling path depress ratio on microstructure and properties. Some reasons of yield ratio overseted standard have been analyzed. The results show that decreasing rolling paths and increasing depress ratio refined grains but unchanged area ratio and interlamellar spacing of pearlite. Yield strength excessively increased but tensile strength unchanged increased yield ratio. So, excellent properties can be obtained by applying the optimization process.

Development of Low Carbon Bainitic Cr-B Steel with High Strength and Good Toughness

2010 ◽  
Vol 146-147 ◽  
pp. 937-940
Author(s):  
Xiang Dong Huo ◽  
Zhang Guo Lin ◽  
Yu Tao Zhao ◽  
Yu Qian Li
Keyword(s):  
High Strength ◽  
Polygonal Ferrite ◽  
Steel Plates ◽  
Granular Bainite ◽  
High Yield ◽  
Low Carbon ◽  
Experimental Steel ◽  
Large Size ◽  
Final Microstructure ◽  
Lath Bainite

In order to develop low carbon bainitic Cr-B steel, experimental procedures including melting, thermal simulation study and laboratory hot rolling were adopted. The dynamic CCT diagram was established, microstructure and properties of experimental steel were also analyzed. The transformation temperature of experimental steel lies between 650～400°C and final microstructure changes fromquasi-polygonal ferrite, granular bainite to lath bainite as cooling rate increases from 0.2 to 50°C.s-1. The microstructure of steel plates, air cooled or water cooled to 530°C then air cooled, is mainly composed of granular bainite and quasi-polygonal ferrite, and the large size islands in granular bainite are responsible for the low strength and poor toughness. However, steel plate with lath bainite, water cooled to roomtemperature, boasts high yield strength (672MPa) and superior impact toughness (127J at -20°C). Therefore, it is feasible to produce low carbon bainitic Cr-B steel with high strength and good toughness through controlling cooling parameters.

Effect of Niobium on the Microstructure and Mechanical Properties of Low Carbon Steel Plate with Intercritical Quenching

2010 ◽  
Vol 152-153 ◽  
pp. 1382-1386
Author(s):  
De Hui Zou ◽  
Zhi Fang Peng ◽  
Ping He Li ◽  
Ai Min Guo
Keyword(s):  
Mechanical Properties ◽  
Carbon Steel ◽  
Low Temperature ◽  
Low Carbon Steel ◽  
Yield Ratio ◽  
Steel Plates ◽  
Low Carbon ◽  
Niobium Content ◽  
Microstructure And Mechanical Properties ◽  
Low Temperature Toughness

The microstructure and mechanical properties of the low carbon steel plates containing Niobium content of 0.038%, 0.063% and 0.082% with intercritical quenching were studied by SEM, TEM, tensile and impact tests. The results showed that the intercritical quenching steel with high Niobium content can gain the fine microstructure , but also easily obtain the martensite, which made the strength very high but low temperature toughness very low, however, the steel with low Niobium content can not reach enough austenitization level, which caused both low temperature and yield ratio high relatively. So in the given rolling and heat treatment process, there was suitable Niobium content can contribute to obtain the optimal austenization level resulting in the good combination of strength, yield ratio, elongation and low temperature toughness after intercritical quenching in the low carbon steel.

ASTM A710

Alloy Digest ◽  
1990 ◽  
Vol 39 (4) ◽  
Keyword(s):  
Fracture Toughness ◽  
Tensile Properties ◽  
Precipitation Hardening ◽  
Steel Plate ◽  
High Strength ◽  
Heat Treating ◽  
Low Carbon ◽  
Bethlehem Steel Corporation ◽  
Strength Alloy ◽  
Carbon Precipitation

Abstract ASTM A710 is a low-carbon, precipitation hardening high-strength alloy steel plate. It is well suited to critical applications. This datasheet provides information on composition and tensile properties as well as fracture toughness. It also includes information on heat treating and joining. Filing Code: SA-446. Producer or source: Bethlehem Steel Corporation.

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