Crystallographic Texture Control Helps Improve Pipeline Steel Resistance to Hydrogen-Induced Cracking

2010 ◽  
Author(s):  
V. Venegas ◽  
O. Herrera ◽  
F. Caleyo ◽  
J. M. Hallen ◽  
T. Baudin
Keyword(s):  
Grain Boundaries ◽  
Crystallographic Texture ◽  
Pipeline Steel ◽  
Low Carbon Steel ◽  
Rolling Process ◽  
Warm Rolling ◽  
American Petroleum Institute ◽  
Low Carbon ◽  
Steel Rolling ◽  
Hydrogen Induced Cracking

Low-carbon steel specimens, all within API (American Petroleum Institute) specifications, were produced following different thermomechanical paths. After austenization, the samples were rolled and recrystallized. The rolling process was carried out using different reduction-in-thickness degrees and finishing temperatures. The investigated steels showed similar microstructural features but differed considerably in their crystallographic textures and grain boundary distributions. After cathodic hydrogen charging, hydrogen-induced cracking (HIC) was detected in the hot-rolled recrystallized steels, whereas the cold and warm-rolled recrystallized steels proved resistant to this damage. Among the investigated specimens, the HIC-stricken show either the strongest {001}ND texture fiber, the smallest fraction of low-angle grain boundaries, or the weakest {111}ND (γ) texture fiber ({hkl}ND representing crystallographic orientations with {hkl} planes parallel to the steel rolling plane). In contrast, the HIC-resistant steels show the weakest {001}ND texture fiber, the largest fraction of low-angle grain boundaries, and the strongest γ fiber. These results support the hypothesis of this and previous works, that crystallographic texture control, through warm rolling schedules, helps improve pipeline steel resistance to hydrogen-induced cracking.

scholarly journals Impact of Warm Rolling Process Parameters on Crystallographic Textures, Microstructure and Mechanical Properties of Low-Carbon Boron-Bearing Steels

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 927 ◽  
Author(s):  
Mandana Zebarjadi Sar ◽  
Silvia Barella ◽  
Andrea Gruttadauria ◽  
Davide Mombelli ◽  
Carlo Mapelli
Keyword(s):  
Mechanical Properties ◽  
Microstructural Analysis ◽  
Low Carbon Steel ◽  
Rolling Process ◽  
Warm Rolling ◽  
Low Carbon ◽  
Different Temperatures ◽  
High Boron ◽  
Experimental Trials ◽  
Boron Steels

The effect of the warm rolling process on the microstructure and the mechanical properties of low-carbon high-boron steels are studied in this work. To investigate these effects, boron-bearing low-carbon steel, subjected to roll at three different temperatures, was studied symmetrically and asymmetrically. The results of the experimental trials achieved by mechanical and microstructural analysis revealed that the use of warm rolling can represent a favorable method to suppress strain aging completely, and to eliminate the fluting effect and yield point elongation. In addition, the tensile and elongation properties are modified with the formation of boron nitride precipitates and dislocations in different thermomechanical conditions.

The Effect of Severe Plastic Deformation on the Brittle-Ductile Transition in Low Carbon Steel

2009 ◽  
Vol 633-634 ◽  
pp. 471-480
Author(s):  
Masaki Tanaka ◽  
Kenji Higashida ◽  
Tomotsugu Shimokawa
Keyword(s):  
Fracture Toughness ◽  
Carbon Steel ◽  
Grain Boundaries ◽  
Three Dimensional ◽  
Low Carbon Steel ◽  
Dislocation Dynamics ◽  
Strain Rates ◽  
Low Carbon ◽  
Dislocation Source ◽  
Brittle Ductile Transition

Brittle-ductile transition (BDT) behaviour was investigated in low carbon steel deformed by an accumulative roll-bonding (ARB) process. The temperature dependence of its fracture toughness was measured by conducting four-point bending tests at various temperatures and strain rates. The fracture toughness increased while the BDT temperature decreased in the specimens deformed by the ARB process. Arrhenius plots between the BDT temperatures and the strain rates indicated that the activation energy for the controlling process of the BDT was not changed by the deformation with the ARB process. It was deduced that the decrease in the BDT temperature by grain refining was not due to the increase in the dislocation mobility controlled by short-range barriers. Quasi-three-dimensional simulations of dislocation dynamics, taking into account of crack tip shielding due to dislocations, were performed to investigate the effect of a dislocation source spacing along a crack front on the BDT. The simulation indicated that the BDT temperature is decreased with decreasing in the dislocation source spacing. Molecular dynamics simulations revealed that moving dislocations were impinged against grain boundaries and were reemitted from there with increasing strain. It indicates that grain boundaries can be new sources in ultra-fine grained materials, which increases toughness at low temperatures.

scholarly journals Microstructure Examinations in Corners of the Low-Carbon Steel Slabs from Continuos Caster Machine

2016 ◽  
Vol 61 (4) ◽  
pp. 2051-2056 ◽  
Author(s):  
G. Kwinta ◽  
S. Kara ◽  
B. Kalandyk ◽  
R. Zapała ◽  
P. Pałka
Keyword(s):  
Surface Defects ◽  
Cast Steel ◽  
Continuous Process ◽  
Low Carbon Steel ◽  
Casting Process ◽  
American Petroleum Institute ◽  
Test Material ◽  
Low Carbon ◽  
Destructive Testing ◽  
Gaseous Fuels

Abstract The exposed selvedge layers in slabs cast by the continuous process should be free from surface defects, which in most cases appear in the form of cracks on the casting surface and run to its interior. In addition to the parameters of the casting process, the occurrence of such defects depends on the chemical composition of cast steel, on the segregation of surface active elements and formation of the precipitates of carbides, nitrides and other phases. Due to the frequent occurrence of defects in corners of the slabs, non-destructive testing was performed on the mechanically cleaned surfaces of slabs. The test material was low-carbon API(American Petroleum Institute API 5L standard) steel micro alloyed with Nb and Ti designed for the production of pipes to handle gas, oil and other liquid and gaseous fuels. Despite the use of different methods of inspection, i.e. ultrasonic, magnetic particle and penetrant, cracks were not traced in the examined material. Then, from the corners of the examined slabs, specimens were cut out for metallographic examinations. The main purpose of these examinations was to disclose the presence of possible cracks and micro cracks on the surfaces transversal and longitudinal to the direction of casting. At the same time, studies were conducted to establish the number and morphology of non-metallic inclusions in selvedge layers of the slab corners and axis. Additionally, hardness of the slabs was measured. The conducted studies revealed only some minor differences in the slab hardness along its axis (130 ÷ 135 HB) and in selvedge layers (120 ÷ 123 HB).

Effect of Cooling Condition after Warm Rolling on the Development of Microstructure and Texture in an ELC Steel

2005 ◽  
Vol 105 ◽  
pp. 259-264
Author(s):  
Arunansu Haldar ◽  
R.K. Ray ◽  
A.J. Khan
Keyword(s):  
Low Temperatures ◽  
Low Carbon Steel ◽  
Warm Rolling ◽  
The Other ◽  
Texture Development ◽  
Low Carbon ◽  
Deformation Bands ◽  
Cooling Conditions ◽  
Different Temperatures ◽  
Rolling Temperatures

The microstructure and texture development in an extra low carbon steel during warm rolling (~ 80%) in a single pass at four different temperatures and at two different cooling conditions were studied. The g fibre texture develops at lower warm rolling temperatures (500 °C and 600 °C) and a very weak a fibre develops at higher rolling temperatures (700 °C and 800 °C). Very little or no difference in microstructure and texture development was observed under two cooling conditions at four rolling temperatures. No significant effect of cooling rates could be found at higher temperatures of rolling due to very fast static recrystallisation after rolling which also caused the weakening of texture. On the other hand deformation bands produced at low temperatures rolling helped in forming strong g fibre textures.

Modeling austenite–ferrite transformation in low carbon steel using the cellular automaton method

2004 ◽  
Vol 19 (10) ◽  
pp. 2877-2886 ◽  
Author(s):  
Y.J. Lan ◽  
D.Z. Li ◽  
Y.Y. Li
Keyword(s):  
Carbon Steel ◽  
Cellular Automaton ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Low Carbon Steel ◽  
Carbon Diffusion ◽  
Cellular Automaton Model ◽  
Low Carbon ◽  
Austenite Grain ◽  
Ferrite Transformation

Austenite–ferrite transformation at different isothermal temperatures in low carbon steel was investigated by a two-dimensional cellular automaton approach, which provides a simple solution for the difficult moving boundary problem that governs the ferrite grain growth. In this paper, a classical model for ferrite nucleation at austenite grain boundaries is adopted, and the kinetics of ferrite grain growth is numerically resolved by coupling carbon diffusion process in austenite and austenite–ferrite (γ–α) interface dynamics. The simulated morphology of ferrite grains shows that the γ–α interface is stable. In this cellular automaton model, the γ–α interface mobility and carbon diffusion rate at austenite grain boundaries are assumed to be higher than those in austenite grain interiors. This has influence on the morphology of ferrite grains. Finally, the modeled ferrite transformation kinetics at different isothermal temperatures is compared with the experiments in the literature and the grid size effects of simulated results are investigated by changing the cell length of cellular automaton model in a set of calculations.

THE EFFECTS OF ACCUMULATIVE ROLL BONDING PROCESS ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF IF STEEL

2008 ◽  
Vol 22 (18n19) ◽  
pp. 2866-2873 ◽  
Author(s):  
SAEED TAMIMI ◽  
MOSTAFA KETABCHI ◽  
NADER PARVIN
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Accumulative Roll Bonding ◽  
Low Carbon Steel ◽  
Rolling Process ◽  
Low Carbon ◽  
Roll Bonding ◽  
Rolling Pass ◽  
Steel Strips ◽  
Wire Brushing

This work aims to investigate whether accumulative roll bonding (ARB) is an effective grain refinement technique for ultra-low-carbon steel strips containing 0.004% C. For this purpose, a number of ARB processes were performed at 500 °C, with 50% reduction in area of each rolling pass. It was found that both the ultimate grain size achieved, as well as the degree of bonding, depend on number of rolling pass and reduction of area as a whole. The mean grain size was obtained using AFM was about 130nm. The mechanical properties after rolling and cooling were obtained. Also, the fracture surfaces were studied by Scanning Electron Microscopy (SEM). It was concluded that metal's tensile strengths increased by 334% while the ductility dropped from a prerolled value of 50.5% to 2.6%. Effect of wire brushing on samples observed too. It increased on the wire brushed sheet for 7 HV. The rolling process was stopped when cracking of the edges became pronounced.

Effect of Heat Treatments on Microstructure and Mechanical Properties of Low Carbon Steel Pipes Welded by Induction Process

2014 ◽  
Vol 887-888 ◽  
pp. 1301-1306
Author(s):  
Zakaria Boumerzoug ◽  
Lakhdar Lakhdari
Keyword(s):  
Mechanical Properties ◽  
Isothermal Annealing ◽  
Pipeline Steel ◽  
Low Carbon Steel ◽  
Tensile Tests ◽  
Heat Treatments ◽  
Low Carbon ◽  
Steel Pipes ◽  
Induction Process ◽  
Isothermal Heat Treatments

In this work, the effect of isothermal heat treatments on microstructure evolution and mechanical properties after welding by induction of A37 pipeline steel have been studied by scanning electron microscopy, hardness measurements, and tensile tests. Microstructural evolution in welded joint was identified after isothermal annealing from 200 until 900 °C.

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