Study on Microstructure and Properties of X80 Pipeline Steel

2014 ◽  
Vol 941-944 ◽  
pp. 138-141 ◽  
Author(s):  
Xiang Dong Huo ◽  
Feng Dong ◽  
Lie Jun Li
Keyword(s):  
Grain Refinement ◽  
Impact Energy ◽  
Acicular Ferrite ◽  
Precipitation Hardening ◽  
Pipeline Steel ◽  
High Strength ◽  
Experimental Methods ◽  
Microstructural Characteristics ◽  
X80 Pipeline Steel ◽  
Toughness Improvement

Experimental methods, such as OM, SEM and X-EDS, were used to study the microstructure of X80 pipeline steel. It mainly consists of fine acicular ferrite (AF). X80 pipeline steel possesses high strength and impact energy at-30°C approaches to 400J. Grain refinement and precipitation hardening are the main reasons for high strength, and toughness improvement can be attributed to grain refinement and particular microstructural characteristics of AF.

Development of Hot Rolled Ship Plate with High Strength and High Toughness

2013 ◽  
Vol 690-693 ◽  
pp. 106-109 ◽  
Author(s):  
Xiang Dong Huo ◽  
Lin Guo ◽  
Jin Song Feng ◽  
Chao Luo ◽  
Jun Qu
Keyword(s):  
Acicular Ferrite ◽  
Precipitation Hardening ◽  
High Strength ◽  
Experimental Methods ◽  
Polygonal Ferrite ◽  
High Toughness ◽  
Microstructural Constituent ◽  
Lath Width ◽  
Nanometer Particles ◽  
Hot Rolled

A new hot-rolled ship plate with high strength and high toughness is successfully developed through chemical composition design and TMCP process. Experimental methods, such as OM, TEM and X-EDS, were used to study the microstructure and precipitates of steel. The primary microstructural constituent is acicular ferrite, quasi-polygonal ferrite with second constituents along grain boundaries. Lath width of acicular ferrite is about 1μm. Cubic particles about several hundreds nanometers and nanometer particles exist in experimental steel. It can be concluded that acicular ferrite is the main reason for high strength and super toughness. precipitation hardening due to dispersed precipitations of carbonitrides can not be overlooked.

Mechanical Properties and CO2 Corrosion Behavior of High Strength and Toughness X80 Pipeline Steel

2014 ◽  
Vol 1010-1012 ◽  
pp. 1709-1712
Author(s):  
Li Dong Wang ◽  
Feng Lei Liu ◽  
Hui Bin Wu
Keyword(s):  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Acicular Ferrite ◽  
Pipeline Steel ◽  
High Strength ◽  
Strengthening Mechanism ◽  
Granular Bainite ◽  
X80 Pipeline Steel ◽  
Better Than ◽  
Strength And Toughness

A type of X80 grade high strength and toughness pipeline steel was designed and researched. The strengthening mechanism of the steel was analyzed by SEM, TEM and XRD, and the CO2corrosion behavior of the steel was simulated by high-temperature and high-pressure autoclave. The result shows that the microstructure of the base metal is mainly acicular ferrite with a small amount of granular bainite. Acicular ferrite consists of laths which occlude and interweave with each other, and there are many dislocation and carbonitrides distributing in acicular ferrite, which made the pipeline steel have good strength and toughness. Under the simulation of the actual working conditions, the activity of reactants is low at 30°C, so the corrosion rate is smaller at this temperature; the maximum of corrosion rate occurs at 60°C; when the temperature increases to 90°C, the corrosion rate is lower than that of 60°C, that is because hindering corrosion effect which take by the acceleration deposit of corrosion product is better than the acceleration corrosion reactions.

Strengthening Mechanisms of Vanadium Micro-Alloyed Reinforcing Steel Bar

2011 ◽  
Vol 130-134 ◽  
pp. 942-945
Author(s):  
Lie Jun Li ◽  
Xiang Dong Huo ◽  
Lin Guo
Keyword(s):  
Yield Strength ◽  
Grain Refinement ◽  
Precipitation Hardening ◽  
High Strength ◽  
Experimental Methods ◽  
Strengthening Mechanisms ◽  
Large Numbers ◽  
Steel Bar ◽  
Micro Alloyed Steel ◽  
Grain Refinement Strengthening

High strength vanadium micro-alloyed steel with yield strength of 600MPa has been developed based on commercial 20MnSi steel bar. Experimental methods, such as OM, SEM and TEM, were used to study the experimental steels. Compared with 20MnSi, steel 20MnSiV boasts much finer microstructure, and large numbers of nanometer precipitates exist in the specimens of 20MnSiV. Analysis shows that strength of 20MnSiV dramatically increases through grain refinement strengthening and precipitation hardening of nanometer VCN particles.

Mechanical Properties and Aging Behavior of Ultrafine Grained Al-Ag Alloy Fabricated by Accumulative Roll-Bonding

2014 ◽  
Vol 794-796 ◽  
pp. 851-856
Author(s):  
Tadashiege Nagae ◽  
Nobuhiro Tsuji ◽  
Daisuke Terada
Keyword(s):  
Mechanical Properties ◽  
Grain Refinement ◽  
Accumulative Roll Bonding ◽  
Precipitation Hardening ◽  
Tensile Elongation ◽  
Solution Treatment ◽  
High Strength ◽  
Subsequent Aging ◽  
Roll Bonding ◽  
Ultrafine Grained

Accumulative roll-bonding (ARB) process is one of the severe plastic deformation processes for fabricating ultrafine grained materials that exhibit high strength. In aluminum alloys, aging heat treatment has been an important process for hardening materials. In order to achieve good mechanical properties through the combination of grain refinement hardening and precipitation hardening, an Al-4.2wt%Ag binary alloy was used in the present study. After a solution treatment at 550°C for 1.5hr, the alloy was severely deformed by the ARB process at room temperature (RT) up to 6 cycles (equivalent strain of 4.8). The specimens ARB-processed by various cycles (various strains) were subsequently aged at 100, 150, 200, 250°C, and RT. The hardness of the solution treated (ST) specimen increased by aging. On the other hand, hardness of the ARB processed specimen decreased after aging at high temperatures such as 250°C. This was probably due to coarsening of precipitates or/and matrix grains. The specimen aged at lower temperature showed higher hardness. The maximum harnesses achieved by aging for the ST specimen, the specimens ARB processed by 2 cycles, 4 cycles and 6 cycles were 55HV, 71HV, 69HV and 65HV, respectively. By tensile tests it was shown that the strength increased by the ARB process though the elongation decreased significantly. However, it was found that the tensile elongation of the ARB processed specimens was improved by aging without sacrificing the strength. The results suggest that the Al-Ag alloy having large elongation as well as high strength can be realized by the combination of the ARB process for grain refinement and the subsequent aging for precipitation hardening.

scholarly journals Influence of the ultrasonic surface rolling process on stress corrosion cracking susceptibility of high strength pipeline steel in neutral pH environment

RSC Advances ◽  
2017 ◽  
Vol 7 (59) ◽  
pp. 36876-36885 ◽  
Author(s):  
Bingying Wang ◽  
Yu Yin ◽  
Zhiwei Gao ◽  
Zhenbo Hou ◽  
Wenchun Jiang
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Pipeline Steel ◽  
High Strength ◽  
Rolling Process ◽  
Corrosion Cracking ◽  
X80 Pipeline Steel ◽  
Enhancement Technique ◽  
Neutral Ph ◽  
Developed Surface

A developed surface enhancement technique, USRP, was applied on X80 pipeline steel and the stress corrosion cracking susceptibility was studied.

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.

Effect of Ti on the Microstructures and Toughness of TMCP-600 Steel Weld Metals

2013 ◽  
Vol 746 ◽  
pp. 462-466
Author(s):  
Jin Hyun Koh ◽  
Bok Su Jang
Keyword(s):  
Weld Metal ◽  
Impact Energy ◽  
Acicular Ferrite ◽  
Gas Metal Arc Welding ◽  
Control Process ◽  
High Strength ◽  
Weld Metal Microstructure ◽  
Metal Microstructure ◽  
The Impact ◽  
Ti Content

The Ti addition effect on the characteristics of weld metal, such as impact energy, microstructure and nonmetallic inclusions, was investigated to develop a suitable gas metal arc welding wire for the high strength of TMCP (Thermo Mechanical Control Process)-600 steel. The fraction of acicular ferrite which was known to be a favorable weld metal microstructure for toughness was increased with Ti content from 0.002% to 0.025%, The impact energy of weld metal was increased whereas the ductile to brittle transition temperature was decreased with increasing Ti content. The size of nonmetallic inclusion was decreased while the density of inclusions was decreased with increasing Ti content. It was found that Ti content on the weld metal toughness had a plus effect by increasing the fraction of acicular ferrite in the weld metal microstructure.

Control Final Cooling Temperature on High Strength of the Pipeline Radio Yield Influence

2011 ◽  
Vol 117-119 ◽  
pp. 310-314
Author(s):  
Yong Jie Ma ◽  
Xun He ◽  
Guang Liang Zhang
Keyword(s):  
Pipeline Steel ◽  
Steel Production ◽  
High Strength ◽  
Yield Ratio ◽  
X80 Pipeline Steel ◽  
Steel Rolling ◽  
Cooling Temperature ◽  
Lath Bainite ◽  
Bainite Microstructure ◽  
Rolling Technology

In high strength pipeline steel rolling technology, the control of final cooling temperature of different microstructure, different microstructure of pipeline steel tensile strength, yield strength and the effects of different, thus determine its yield ratio differences. The results show that with lath bainite microstructure of the pipeline steel than with acicular ferrite microstructure of the pipeline steel with lower yield ratio, at the same time lath bainite microstructure in small dispersed precipitates in pipeline steel X80 pipeline steel to reduce the yield ratio is beneficial, for high strength pipeline steel production technology to provide the theory basis.

Precipitation Hardening of Titanium Carbides in Ti Micro-Alloyed Ultra-High Strength Steel

2011 ◽  
Vol 284-286 ◽  
pp. 1275-1278
Author(s):  
Xiang Dong Huo ◽  
Sheng Xia Lv ◽  
Xin Ping Mao ◽  
Qi Lin Chen
Keyword(s):  
Precipitation Hardening ◽  
High Strength Steels ◽  
High Strength ◽  
Experimental Methods ◽  
Chemical Phase ◽  
Ultra High Strength Steel ◽  
Average Grain Size ◽  
Chemical Phase Analysis ◽  
Ultra High Strength Steels ◽  
Hot Rolled

New 700MPa hot rolled ultra-high strength steels were successfully developed by using Ti micro-alloying technology in CSP line. Experimental methods, such as OM, TEM and chemical phase analysis, were used to study the experimental steel. The microstructure is composed of quasi-polygonal ferrite grains, whose average grain size is about 4μm. Large number of nanometer TiC particles distribute along dislocations. The mass fraction of MX phase is 0.0793wt%, in which the particles smaller than 10nm account for 33.7%. The contribution of precipitation hardening resulting from nanometer particles is calculated as approximate 158MPa.

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