scholarly journals Effect of Hot Working Processes on Microstructure and Mechanical Properties of Pipeline Steel

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 860
Author(s):  
Huiling Ji ◽  
Yiwei Zhang ◽  
Wenzhao Lu ◽  
Bang Wei ◽  
Xiaomin Yuan
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Cooling Rate ◽  
Acicular Ferrite ◽  
Pipeline Steel ◽  
Granular Bainite ◽  
Isothermal Quenching ◽  
Electron Backscattered Diffraction ◽  
Quenching Temperature ◽  
Treatment Conditions

The microstructure and microhardness of X70 pipeline steel were investigated after conducting different processing routes. The microstructure was characterized using optical and electron microscopy. Scanning electron microscopy equipped with electron backscattered diffraction (EBSD) and transmission electron microscopy techniques were applied for investigation of different thermal processing treatment conditions. Mechanical properties were characterized by a microhardness tester. The results show that the microstructure mainly consists of granular bainite, acicular ferrite and a small amount of M/A constituents under hot rolling states. There are many dislocations inside the acicular ferrite. The thermal simulation experiments show that the microstructure becomes homogeneous with the increase in cooling rate. The acicular ferrite morphology becomes fine and uniform, and the content of M/A constituents increases at the same compression amount. The compression gives rise to the accumulated strain and stored energy, which accelerate the transformation of acicular ferrite and refine the microstructure of the pipeline steel. The microhardness rises with the increase in deformation ratio and cooling rate. The microstructure of the pipeline steel subjected to the isothermal quenching process is ultrafine ferrite and M/A islands. When the isothermal quenching temperature reaches 550 °C, a small amount of upper bainite appears in the microstructure. With the increase in isothermal quenching temperature, the microhardness decreases. Acicular ferrite is a better candidate microstructure than ultrafine ferrite for the pipeline steels.

scholarly journals Effect of heat treatment on the microstructure and mechanical properties of a low-carbon X80 pipeline steel

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
B.C. Acosta-Cinciri ◽  
N.M. López-Granados ◽  
J.A. Ramos-Banderas ◽  
C.A. Hernández-Bocanegra ◽  
P. Garnica-González ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Pipeline Steel ◽  
American Petroleum Institute ◽  
The Other ◽  
Low Carbon ◽  
Electron Backscattered Diffraction ◽  
X80 Pipeline Steel ◽  
Microstructure And Mechanical Properties ◽  
Treatment Conditions

Abstract In this work, the effect of heat treatment conditions on the microstructure and mechanical properties of an American Petroleum Institute (API) X80 steel with a low carbon content of ~0.02% wt., destined for the manufacture of pipelines and pipeline transmission systems by welding, was investigated. Samples were heat treated under different conditions and then were characterized by scanning electron microscopy (SEM), orientation image microscopy (OIM), and electron backscattered diffraction (EBSD). The results showed that when the steel is fastly cooled from the austenitic field (990°C), the mechanical properties increase significantly [ultimate tensile strength (UTS) >1,100 MPa, yield strength (YS) 900 MPa, and elongation 27%] due to the high percentage of martensite (M) present in the microstructure (95%). In contrast, when the cooling rate decreases and the treatment conditions remain at/or above the bainitic/martensitic transformation (from 990°C to 600°C and 450°C), the mechanical properties are decreased by almost 50% because of the decrease in the percentage of martensite (18%). However, the percentage of elongation increases significantly (38%) due to the presence of other micro-constituents resulting from the phase transformation. On the other hand, the best combination of mechanical properties (UTS above 800 MPa and YS between 610 MPa and 720 MPa) was obtained when the steel acquired a dual-phase microstructure [(martensite/austenite)-(ferrite/martensite)] since the amount of martensite is conserved between 45% and 82%, in combination with the other micro-constituent present in the steel that allows us to achieve elongation percentages close to 30%.

Effect of Cooling Rate on Microstructures and Mechanical Properties of X80 Pipeline Steel

2012 ◽  
Vol 535-537 ◽  
pp. 525-528 ◽  
Author(s):  
Qing Bo Yu
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Volume Fraction ◽  
Pipeline Steel ◽  
Controlled Rolling ◽  
Granular Bainite ◽  
Controlled Cooling ◽  
X80 Pipeline Steel ◽  
Microstructures And Mechanical Properties ◽  
Ferrite Grain Size

The thermal simulation experiments of X80 pipeline steel were performed using Gleeble 1500 thermomechanical simulator. The controlled rolling and controlled cooling experiments were used to investigate the effect of cooling rate on the microstructures and mechanical properties of X80 pipeline steel. The results show that the cooling rate plays an important role in the ferrite grain size and the volume fraction of granular bainite. In order to obtain good comprehensive mechanical properties, it is necessary that the cooling rate should be 12~20°C/s.

scholarly journals Effect of Annealing Process on the Mechanical Properties of X70 Pipeline Steel

2018 ◽  
Vol 186 ◽  
pp. 02001
Author(s):  
Teng-wei Zhu ◽  
Cheng-liang Miao ◽  
Zheng Cheng ◽  
Zhipeng Wang ◽  
Yang Cui ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Tensile Strength ◽  
Annealing Temperature ◽  
Pipeline Steel ◽  
Annealing Process ◽  
X70 Pipeline Steel ◽  
Grain Sizes ◽  
Scanning Electron

The influence of the mechanical properties of X70 pipeline steel under different annealing temperature was studied. The corresponding microstructure was investigated by the Field Emission Scanning Electron Microscopy. The results showed that the yield strength and the tensile strength both experienced from rise to decline with the increase of annealing temperature. The grain sizes were coarse and a large amount of cementite precipitated due to preserving temperature above 550 °, which induced matrix fragmentation and deteriorate the -10 ° DWTT Toughness. There were little changes on the microstructure and mechanical properties when the annealing temperature was under 500 °.

scholarly journals Effect of Roller Quenching on Microstructure and Properties of 300 mm Thickness Ultra-Heavy Steel Plate

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1238
Author(s):  
Jun Han ◽  
Tianliang Fu ◽  
Zhaodong Wang ◽  
Guodong Wang
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Steel Plate ◽  
Temperature Curve ◽  
Steel Plates ◽  
Quenching Temperature ◽  
Microstructure And Properties ◽  
Testing Method ◽  
Average Grain Size ◽  
Length Direction

In this paper, a 300 mm thickness ultra-heavy steel plate was selected as the research object. In addition, special roller quenching equipment and a new testing method were used to measure the quenching temperature curve at different positions of the steel plate. The relationships and corresponding interaction mechanisms between cooling rate, microstructure, and mechanical properties of an ultra-heavy steel plate during roller quenching were investigated. The results indicated that the cooling rate, strength, hardness, and impact energy decreased gradually along the thickness direction of the plate, while the cooling rate, average grain size, and mechanical properties were relatively uniform with little change along the length direction of the plate. The experimental results provide an effective way to further control the microstructure and properties of ultra-heavy steel plates during roller quenching.

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.

Quenching Temperature‘s Impact on the Microstructure and Mechanical Properties of X80 Pipeline Steel

2011 ◽  
Vol 308-310 ◽  
pp. 762-766
Author(s):  
Yong Jie Ma ◽  
Xi Lu Liu ◽  
Guang Liang Zhang
Keyword(s):  
Mechanical Properties ◽  
Pipeline Steel ◽  
X80 Pipeline Steel ◽  
Quenching Temperature ◽  
Austenite Grain ◽  
State Study ◽  
Lath Bainite ◽  
Small Needle ◽  
X80 Steel ◽  
Increased Strength

The state study on mechanical properties’ changes of X80 steel at different quenching temperature. The results showed that the quenching temperature is 1000 °C, X80 Austenite grain coarsening is serious, leading to the production of coarse lath bainite ferrite, resulting in increased strength of X80 steel, toughness and hardness of a serious reduction; When the quenching temperature is 930 °C, and assisted by the appropriate temperatures, can make the X80 steel the small needle-like ferrite-based organizations, to obtain good hardness, strength, ductility and toughness of the match.

The Effect of Quenching Media on the Microstructure and Mechanical Properties of SA508-3 Steel

2011 ◽  
Vol 311-313 ◽  
pp. 974-977 ◽  
Author(s):  
Lu Han Hao ◽  
Ming Yue Sun ◽  
Dian Zhong Li
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Lower Bainite ◽  
Granular Bainite ◽  
Tempered Martensite ◽  
Quenching Media ◽  
Microstructure And Mechanical Properties ◽  
Allotriomorphic Ferrite ◽  
Upper Bainite

Three different quenching media (water, oil and air) were used to compare the effect of cooling rate on the microstructure and mechanical properties of SA508-3 steel. The result has demonstrated that the microstructure for water-quenched specimen is the mixture of martensite and lower bainite, for oil-quenched specimen is the mixture of upper bainite，lower bainite and a little martensite, while for air-cooled specimen is mostly granular bainite. The product of water and oil Q&T was tempered martensite with qualified mechanical properties. The air-cooled granular bainite was translated to massive and allotriomorphic ferrite during tempering, which had poor mechanical properties. To avoid the formation of granular bainite, it is necessary to increase the cooling rate to above 5°C/s.

Microstructure and Mechanical Properties of X70 Pipeline Steel with High H2S Resistance

2015 ◽  
Vol 816 ◽  
pp. 755-760 ◽  
Author(s):  
Jing Li ◽  
Xiu Hua Gao ◽  
Yong Lu ◽  
Lin Xiu Du
Keyword(s):  
Mechanical Properties ◽  
Pipeline Steel ◽  
High Strength ◽  
Granular Bainite ◽  
Second Phase ◽  
Precipitation Behavior ◽  
Experimental Steel ◽  
X70 Pipeline Steel ◽  
The Matrix ◽  
Sour Service

Anti-H2S X70 pipeline steel was developed. The microstructure of X70 pipeline steel was studied by the analysis of OM, SEM and TEM. The precipitation behavior was discussed. The comprehensive mechanical properties, HIC and SCC performance were systematically studied. The results indicated that the microstructure of the experimental steel was mainly acicular ferrite and granular bainite. The second phase precipitates dispersedly distributed in the matrix. The experimental steel possessed excellent strength, plasticity, low temperature toughness and low yield ratio. And therefore, the X70 pipeline steel in the study is suitable for sour service with the high strength, excellent toughness and low HIC&SSC susceptibility.

Effect of Ultra-Fast Cooling Rate on the Microstructure and Mechanical Properties of High Strength Cold-Rolled Sheet under Continuous Annealing

2018 ◽  
Vol 913 ◽  
pp. 311-316
Author(s):  
Kai Zhang ◽  
Ren Bo Song ◽  
Feng Gao ◽  
Wen Jie Niu ◽  
Chi Chen
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Cooling Rate ◽  
High Strength ◽  
Rolled Sheet ◽  
Cooling Rates ◽  
Microstructure And Mechanical Properties ◽  
Average Grain Size ◽  
Cold Rolled ◽  
Fast Cooling

The effect of different fast cooling rates on the microstructure and mechanical properties of the V and Ti microalloyed high strength cold-rolled sheet was studied under laboratory conditions. Five different fast cooling rates were set up as 20°C/s, 50°C/s, 200°C/s, 500°C/s and 1000°C/s, respectively. Optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe the microstructure, and the mechanical properties were also tested. The results showed that with the increase of fast cooling rate from 20°C/s to 1000°C/s, the grains of martensite and ferrite were finer, and the average grain size of both martensite and ferrite decreased from 7.7μm to 3.9μm. The proportion of ferrite in the two phases decreased while that of the martensite increased from 25.7% to 62.1%. The morphology of martensite tended to be lath, and the density of dislocation in the ferrite grains nearby the martensite gradually increased. With cooling rate rising from 20°C/s to 1000°C/s, the yield strength of the experimental steel increased from 381MPa to 1074MPa, and the tensile strength increased from 887MPa to 1199MPa. And the elongation decreased from 14.2% to 7.2%, and the product of strength and elongation decreased from 12.6GPa·% to 8.6GPa·%.

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