Microstructural and Mechanical Properties of the Intercritically Reheated Coarse Grained Heat Affected Zone (ICCGHAZ) of an API 5L X80 Pipeline Steel

2014 ◽  
Vol 783-786 ◽  
pp. 657-662 ◽  
Author(s):  
J.L.M. Andia ◽  
Luís Felipe Guimarães de Souza ◽  
I.S. Bott
Keyword(s):  
Phase Field ◽  
Thermal Cycle ◽  
Pipeline Steel ◽  
Welding Process ◽  
Coarse Grained ◽  
Accelerated Cooling ◽  
Metallographic Analysis ◽  
Dual Phase ◽  
Weld Thermal Cycle ◽  
Cycle Simulation

The weld thermal cycle, depending on the welding process and steel composition can reduce the toughness of the HAZ when compared with the base metal. In the intercritically reheated coarse grained HAZ (ICCGHAZ) region, microstructural transformations from coarse austenite to bainite or martensite are liable to occur. Reheating into the dual phase field temperature and subsequent cooling can lead to the formation of “microphases” commonly referred to Martensite-Austenite (MA) constituent. Due to the C enrichment of the austenite, this region is regarded as local brittle zones (LBZ) and degradation of HAZ toughness can be attributed to the formation of local brittle zones (LBZ) at the ICCGHAZ. This work will discuss the characteristics of the ICCGHAZ of two API5LX80 steels produced by thermomechanical controlled process (TMCP) without accelerated cooling using a finishing rolling temperature in the dual phase field, where the main hardening mechanisms are grain refining and precipitation. Weld thermal cycle simulation, using a Gleeble 3800®, characterised by the peak temperature (Tp) of 800oC and the cooling time from 800 to 500oC (∆t800–500) were applied in order to obtain an ICCGHAZ equivalent to a 2.5, 3 and 4kJ/mm heat input. Charpy-V tests and metallographic analysis using optical and electron microscopy were carried out to evaluate the simulated zone. The results have shown that the ICCGHAZ presented a necklace microstructure at the prior austenite grain boundaries associated with the low impact energy and the presence of the MA microconstituent.

Thermal cycle simulation of welding process in low carbon steel

2011 ◽  
Vol 530 ◽  
pp. 191-195 ◽  
Author(s):  
Z. Boumerzoug ◽  
E. Raouache ◽  
F. Delaunois
Keyword(s):  
Carbon Steel ◽  
Thermal Cycle ◽  
Low Carbon Steel ◽  
Welding Process ◽  
Low Carbon ◽  
Cycle Simulation

scholarly journals Influence of Weld Thermal Cycle on Properties of Flash Butt Welded Mn-Cr-Mo Dual Phase Steel.

1993 ◽  
Vol 33 (7) ◽  
pp. 807-815 ◽  
Author(s):  
P. K. Ghosh ◽  
P. C. Gupta ◽  
O. M. Pal ◽  
R. Avtar ◽  
B. K. Jha ◽  
...  
Keyword(s):  
Thermal Cycle ◽  
Dual Phase Steel ◽  
Dual Phase ◽  
Weld Thermal Cycle

Investigation on the Weldability of a Zr-Ti Microalloyed Pipeline Steel X120

2012 ◽  
Vol 538-541 ◽  
pp. 1478-1483 ◽  
Author(s):  
Yu Qun Yin ◽  
Hong Hong Wang ◽  
Yong Kuan Yao ◽  
Li Li ◽  
Xuan Wei Lei ◽  
...  
Keyword(s):  
Impact Toughness ◽  
Heat Affected Zone ◽  
Heat Input ◽  
Room Temperature ◽  
Pipeline Steel ◽  
Coarse Grained ◽  
Fine Grained ◽  
Cycle Simulation ◽  
Welding Thermal Cycle ◽  
Temperature Impact

Welding thermal cycle simulation with the heat input of 12~25 kJ/cm and practical welding were undertaken to investigate the weldability of a Zr-Ti microalloyed pipeline steel X120. The microstructure in the simulated coarse-grained heat-affected zone was predominantly bainite. The Vickers hardness and room temperature impact toughness of simulated coarse-grained heat-affected zone is 276~297 (HV10) and 208~225 J, respectively. These results indicated that the X120 steel had good weldability. Practical plate welding with the heat input of 21 kJ/cm also showed that the Zr-Ti microalloyed pipeline steel X120 had high yeild strength (895 MPa) and low temperature (-30°C) impact toughness (183 J, 204 J and 208 J in the fusion line, coarse-grained heat-affected zone and fine-grained heat-affected zone, respectively).

scholarly journals Steel Weldability Investigation by Single and Double-Pass Weld Thermal Cycle Simulation

2020 ◽  
Vol 19 (2) ◽  
pp. 209-218
Author(s):  
M. Dunder ◽  
I. Samardzic ◽  
G. Simunovic ◽  
P. Konjatic
Keyword(s):  
Thermal Cycle ◽  
Double Pass ◽  
Weld Thermal Cycle ◽  
Cycle Simulation

Thermal Cycle Simulation of Welding Process in INC 738 LC Superalloy

2017 ◽  
Vol 735 ◽  
pp. 75-79
Author(s):  
Zakaria Boumerzoug ◽  
Saib Cherif
Keyword(s):  
Optical Microscopy ◽  
Thermal Cycle ◽  
Welded Joint ◽  
Rapid Heating ◽  
Welding Process ◽  
The Real ◽  
Temperature Range ◽  
Characterization Techniques ◽  
Heating And Cooling ◽  
Cycle Simulation

This paper is a contribution to the study of the microstructure in welded joint of INC 738 LC. It presents the microstructures obtained after real welding and also after thermal cycle simulation of welding by rapid heating and cooling treatments in specific simulation equipment. We were focusing on the temperature range [900°C, 1100°C] which is the temperature range of main phases occurrence, as coarse γ’primary, fine γ’ secondary and carbides. Optical microscopy and microhardness measurements were used as characterization techniques. We have found that the obtained microstructures by thermal cycle simulation of welding correspond to those observed in the same zone of the real welded joint performed by real welding.

Correlation between dislocation, grain boundary and interface of duplex SS in stress corrosion cracking(SCC)

1990 ◽  
Vol 48 (4) ◽  
pp. 928-929
Author(s):  
Wang Zheng-fang ◽  
Z.F. Wang
Keyword(s):  
Stainless Steel ◽  
Thermal Cycle ◽  
Secondary Phase ◽  
Corrosion Cracking ◽  
Coarse Grained ◽  
Test Environment ◽  
Fine Grained ◽  
Evaluation Test ◽  
Welding Thermal Cycle ◽  
Micro Analysis

The main purpose of this study highlights on the evaluation of chloride SCC resistance of the material,duplex stainless steel,OOCr18Ni5Mo3Si2 (18-5Mo) and its welded coarse grained zone(CGZ).18-5Mo is a dual phases (A+F) stainless steel with yield strength:512N/mm2 .The proportion of secondary Phase(A phase) accounts for 30-35% of the total with fine grained and homogeneously distributed A and F phases(Fig.1).After being welded by a specific welding thermal cycle to the material,i.e. Tmax=1350°C and t8/5=20s,microstructure may change from fine grained morphology to coarse grained morphology and from homogeneously distributed of A phase to a concentration of A phase(Fig.2).Meanwhile,the proportion of A phase reduced from 35% to 5-10°o.For this reason it is known as welded coarse grained zone(CGZ).In association with difference of microstructure between base metal and welded CGZ,so chloride SCC resistance also differ from each other.Test procedures:Constant load tensile test(CLTT) were performed for recording Esce-t curve by which corrosion cracking growth can be described, tf,fractured time,can also be recorded by the test which is taken as a electrochemical behavior and mechanical property for SCC resistance evaluation. Test environment:143°C boiling 42%MgCl2 solution is used.Besides, micro analysis were conducted with light microscopy(LM),SEM,TEM,and Auger energy spectrum(AES) so as to reveal the correlation between the data generated by the CLTT results and micro analysis.

Microstructural Refinement in a Commercial Aluminum Alloy Processed by ECAP Using a Die Channel Angle of 110 Degrees

2015 ◽  
Vol 1114 ◽  
pp. 3-8
Author(s):  
Nicolae Şerban ◽  
Doina Răducanu ◽  
Nicolae Ghiban ◽  
Vasile Dănuţ Cojocaru
Keyword(s):  
Grain Refinement ◽  
Cross Section ◽  
High Strength ◽  
Secondary Phase ◽  
Coarse Grained ◽  
Metallographic Analysis ◽  
Second Phase ◽  
Channel Angle ◽  
Ambient Temperatures ◽  
Fine Grained

The properties of ultra-fine grained materials are superior to those of corresponding conventional coarse grained materials, being significantly improved as a result of grain refinement. Equal channel angular pressing (ECAP) is an efficient method for modifying the microstructure by refining grain size via severe plastic deformation (SPD) in producing ultra-fine grained materials (UFG) and nanomaterials (NM). The grain sizes produced by ECAP processing are typically in the submicrometer range and this leads to high strength at ambient temperatures. ECAP is performed by pressing test samples through a die containing two channels, equal in cross-section and intersecting at a certain angle. The billet experiences simple shear deformation at the intersection, without any precipitous change in the cross-section area because the die prevents lateral expansion and therefore the billet can be pressed more than once and it can be rotated around its pressing axis during subsequent passes. After ECAP significant grain refinement occurs together with dislocation strengthening, resulting in a considerable enhancement in the strength of the alloys. A commercial AlMgSi alloy (AA6063) was investigated in this study. The specimens were processed for a number of passes up to nine, using a die channel angle of 110°, applying the ECAP route BC. After ECAP, samples were cut from each specimen and prepared for metallographic analysis. The microstructure of the ECAP-ed and as-received material was investigated using optical (OLYMPUS – BX60M) and SEM microscopy (TESCAN VEGA II – XMU). It was determined that for the as-received material the microstructure shows a rough appearance, with large grains of dendritic or seaweed aspect and with a secondary phase at grain boundaries (continuous casting structure). For the ECAP processed samples, the microstructure shows a finished aspect, with refined, elongated grains, also with crumbled and uniformly distributed second phase particles after a typical ECAP texture.

Numerical Analysis of Residual Stresses and Distortions in Aluminium Alloy Welded Joints

2015 ◽  
Vol 809-810 ◽  
pp. 443-448 ◽  
Author(s):  
Tomasz Kik ◽  
Marek Slovacek ◽  
Jaromir Moravec ◽  
Mojmir Vanek
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Aluminium Alloy ◽  
Thermal Cycle ◽  
Technology Development ◽  
Welding Process ◽  
Simulation Software ◽  
Structure Knowledge ◽  
Welding Processes ◽  
Element Method

Simulation software based on a finite element method have significantly changed the possibilities of determining welding strains and stresses at early stages of product design and welding technology development. But the numerical simulation of welding processes is one of the more complicated issues in analyses carried out using the Finite Element Method. A welding process thermal cycle directly affects the thermal and mechanical behaviour of a structure during the process. High temperature and subsequent cooling of welded elements generate undesirable strains and stresses in the structure. Knowledge about the material behaviour subjected to the welding thermal cycle is most important to understand process phenomena and proper steering of the process. The study presented involved the SYSWELD software-based analysis of MIG welded butt joints made of 1.0 mm thickness, 5xxx series aluminium alloy sheets. The analysis of strains and the distribution of stresses were carried out for several different cases of fixing and releasing of welded elements.

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