Acicular ferrite nucleation mechanism in laser-MAG hybrid welds of X100 pipeline steel

2021 ◽  
pp. 130603
Author(s):  
Xiaonan Qi ◽  
Xiaonan Wang ◽  
Hongshuang Di ◽  
Xinjun Shen ◽  
Pengcheng Huan ◽  
...  
Keyword(s):  
Acicular Ferrite ◽  
Pipeline Steel ◽  
Nucleation Mechanism ◽  
X100 Pipeline Steel ◽  
Ferrite Nucleation

scholarly journals The Pitting Susceptibility Investigation of Passive Films Formed on X70, X80, and X100 Pipeline Steels by Electrochemical Noise and Mott-Schottky Measurements

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Yang Zhao ◽  
Ping Liang ◽  
Yanhua Shi ◽  
Yunxia Zhang ◽  
Tao Yang
Keyword(s):  
Distribution Function ◽  
Electrochemical Noise ◽  
Pipeline Steel ◽  
Stochastic Theory ◽  
Gumbel Distribution ◽  
Passive Films ◽  
Initiation Rate ◽  
Pipeline Steels ◽  
X100 Pipeline Steel ◽  
Pit Initiation

The pitting susceptibility of passive films formed on X70, X80, and X100 pipeline steels was investigated by means of electrochemical noise (EN) and Mott-Schottky measurements. The EN results were analyzed according to the shot-noise theory and stochastic theory. Pit initiation process was analyzed quantitatively using the Weibull distribution function. Pit growth process was simulated by Gumbel distribution function. The experimental results of Mott-Schottky plots showed that the passive films formed on the three pipeline steels displayed an n-type semiconductor character, and the passive film for X100 pipeline steel has the lowest donor density (ND) among the three passive films. The EN results demonstrated that X100 pipeline steel had the lowest pit initiation rate and pit growth probability, which implied that the X100 pipeline steel had the lowest pitting susceptibility.

scholarly journals Effect of secondary peak temperature on microstructure and toughness in ICCGHAZ of laser-arc hybrid welded X100 pipeline steel joints

2020 ◽  
Vol 9 (4) ◽  
pp. 7838-7849
Author(s):  
Xiaonan Qi ◽  
Hongshuang Di ◽  
Xiaonan Wang ◽  
Zhenguang Liu ◽  
R.D.K Misra ◽  
...  
Keyword(s):  
Pipeline Steel ◽  
Peak Temperature ◽  
Secondary Peak ◽  
X100 Pipeline Steel ◽  
Steel Joints

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.

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