Microstructure and Toughness of Weld CGHAZ Under Different Heat Input for X90 High Strength Pipeline Steel

2016 ◽  
Author(s):  
Liuqing Yang ◽  
Yongli Sui ◽  
PeiPei Xia ◽  
Die Yang ◽  
Yongqing Zhang
Keyword(s):  
Impact Toughness ◽  
Impact Energy ◽  
Heat Input ◽  
Pipeline Steel ◽  
Charpy Impact ◽  
Optical Microscope ◽  
Granular Bainite ◽  
Alloy Content ◽  
Welding Heat Input ◽  
The Impact

Two kinds of industry trial X90 pipeline steel which had different chemical composition were chosen as experimental materials, and the grain coarsening, microstructure evolution characteristics and the variation rules of low-temperature impact toughness in weld CGHAZ of this two steel under different welding heat input were studied by physical thermal simulation technology, SEM, optical microscope and Charpy impact test. The results show that microstructure in weld CGHAZ of 1# steel is mainly bainite ferrite (BF) and most of the M/A constituents are blocky or short rod-like; the grains of 2# steel are coarse and there is much granular bainite (GB), meanwhile M/A constituents become coarse and their morphology is changing from block to elongated laths; alloy content of X90 pipeline steel under different welding heat input has great effect on the grain size of original austenite, and when heat input is lower than 2.0KJ/mm, Charpy impact toughness in CGHAZ of lower alloy content pipeline steel is good; as heat input increases, impact toughness in CGHAZ of 1# steel is on the rise, and it is high (between 260J and 300J) when heat input is between 2.0KJ/mm and 2.5KJ/mm and the scatter of impact energy is small; impact toughness of 2# steel decreases gradually and the impact energy has obvious variability.

Microstructure and Properties of Weld CGHAZ under Different Heat Input for X90 Pipeline Steel

2016 ◽  
Vol 850 ◽  
pp. 943-949
Author(s):  
Liu Qing Yang ◽  
Yong Li Sui ◽  
Pei Pei Xia ◽  
Hai Hong Zhao ◽  
Zhang Hua Yin
Keyword(s):  
Impact Toughness ◽  
Impact Energy ◽  
Heat Input ◽  
Pipeline Steel ◽  
Charpy Impact ◽  
Optical Microscope ◽  
Granular Bainite ◽  
Alloy Content ◽  
Low Temperature Impact Toughness ◽  
The Impact

Two kinds of industry trial X90 pipeline steels which have different chemical composition were chosen as test objects, and the grain coarsening, microstructural characteristics and the variation rules of low-temperature impact toughness in weld CGHAZ of this two steel under different welding heat input were studied by physical thermal simulation technology, SEM, optical microscope and Charpy impact tests. The results showed that the microstructure in weld CGHAZ of 1# steel was mainly bainite ferrite (BF) and most of the M/A constituents were blocky or short rod-like; the grains of 2# steel were coarse and there was much granular bainite (GB). Meanwhile M/A constituents became coarser and their morphology changed from block to long bar; alloy content of X90 pipeline steel under different weld heat input had great effect on the grain size of original austenite. When heat input was lower than 20KJ/cm, the impact toughness in CGHAZ of lower alloy content pipeline steel was good; as heat input increased, impact toughness in CGHAZ of 1# steel increased to the values between 260J and 300J when heat input was between 20KJ/cm and 25KJ/cm and the dispersion of impact energy was small. The impact toughness of 2# steel decreased gradually and the impact energy had the obvious dispersion.

Effects of Zirconium on Impact Toughness for the Hull Structure Steel Plate

2014 ◽  
Vol 644-650 ◽  
pp. 4932-4935
Author(s):  
Tie Li Qi
Keyword(s):  
Impact Toughness ◽  
Impact Energy ◽  
Heat Input ◽  
Steel Plate ◽  
Sharp Decline ◽  
Large Size ◽  
Welding Heat Input ◽  
Hull Structure ◽  
Large Heat ◽  
The Impact

The Gleeble3500 combined with SEM, TEM and other experimental methods are employed in this paper to investigate the effects of zirconium content on impact toughness of heat affected zone (HAZ) of hull structure steel plate during the large heat input welding. The results showed when 0.01% zirconium were added in the steel, the impact energy reached 224 J at-60°C experienced 150 kJ/cm welding heat input. But the large-size rectangular inclusions are found in CGHAZ when 0.02% zirconium were added in the steel, the impact energy fell to 38 J at-60°C experienced 150 kJ/cm welding heat input, the large-size inclusions, especially rectangular inclusion, were the main cause for the sharp decline of low temperature toughness after welding.

scholarly journals Effect of Welding Heat Input on Microstructure and Impact Toughness in the Simulated CGHAZ of Low Carbon Mo-V-Ti-N-B Steel

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1997
Author(s):  
Mingliang Qiao ◽  
Huibing Fan ◽  
Genhao Shi ◽  
Leping Wang ◽  
Qiuming Wang ◽  
...  
Keyword(s):  
Impact Toughness ◽  
Heat Input ◽  
Acicular Ferrite ◽  
Granular Bainite ◽  
Equivalent Diameter ◽  
Low Carbon ◽  
Welding Heat Input ◽  
Lath Bainite ◽  
Gleeble 3500 ◽  
The Impact

Welding thermal cycles with heat inputs ranging from 25 to 75 kJ/cm were performed on a Gleeble 3500. The impact energy improved significantly (from 10 to 112 J), whereas the simulated coarse-grain heat-affected zone (CGHAZ) microstructure changed from lath bainite ferrite (LBF) and granular bainite ferrite (GBF) + martensite/austenite (M/A) to acicular ferrite (AF) + polygonal ferrite (PF) + M/A as the heat input increased. Simultaneously, the mean coarse precipitate sizes and the degree of V(C,N) enrichment on the precipitate surface increased, which provided favorable conditions for intragranular ferrite nucleation. The Ar3 of CGHAZ increased from 593 °C to 793 °C with increasing heat inputs; the longer high-temperature residence time inhibited the bainite transformation and promoted the ferrite transformation. As a result, acicular ferrite increased and bainite decreased in the CGHAZ. The CGHAZ microstructure was refined for the acicular ferrite segmentation of the prior austenite, and the microstructure mean equivalent diameter (MED) in the CGHAZ decreased from 7.6 µm to 4.2 µm; the densities of grain boundaries higher than 15° increased from 20.3% to 45.5% and significantly increased the impact toughness. The correlation of heat input, microstructure, and impact toughness was investigated in detail. These results may provide new ideas for the development of high welding heat input multiphase steels.

Impact Toughness Characteristics of SM570-TMC Steel Joint Using Welding Wire Containing 0.4% Nickel at Different Level of Heat Input

2020 ◽  
Vol 867 ◽  
pp. 117-124
Author(s):  
Herry Oktadinata ◽  
Winarto Winarto ◽  
Dedi Priadi ◽  
Eddy S. Siradj ◽  
Ario S. Baskoro
Keyword(s):  
Impact Toughness ◽  
Heat Input ◽  
High Heat ◽  
Optical Microscope ◽  
Butt Joint ◽  
Welding Wire ◽  
Steel Joint ◽  
Microstructure Observation ◽  
High Heat Input ◽  
The Impact

The study was conducted to evaluate the impact toughness of flux-cored arc welded of SM570-TMC steel joint under different heat inputs, 0.9 kJ/mm (low heat input) and 1.6 kJ/mm (high heat input). Welding wire containing 0.4%Ni was selected on this experiment. Multi-pass welds were performed on SM570-TMC steel plate of 16 mm in thickness with a single V-groove butt joint on flat position (1G). The evaluation consists of observations on microstructure using an optical microscope and SEM-EDS, and mechanical properties including tensile, microhardness Vickers and Charpy V-notch (CVN) impact test at temperatures of 25, 0 and-20 °C. Results showed that the impact toughness of the base metal (BM) was higher than the weld metal (WM) at all test temperatures. Hardness and impact toughness of WM at low heat input was observed higher than when applied a high heat input. The welded samples at low and high heat inputs had high of tensile strength, and the fracture seemly occurs on the BM. Microstructure observation showed that at a high heat input, larger grains and microsegregation were observed. It might affect on decreasing their impact property.

scholarly journals Effect of Heat Treatment on Microstructure and Impact Toughness of Ti-6Al-4V Manufactured by Selective Laser Melting Process

2017 ◽  
Vol 62 (2) ◽  
pp. 1341-1346 ◽  
Author(s):  
K.-A. Lee ◽  
Y.-K. Kim ◽  
J.-H. Yu ◽  
S.-H. Park ◽  
M.-C. Kim
Keyword(s):  
Heat Treatment ◽  
Impact Toughness ◽  
Selective Laser Melting ◽  
Impact Energy ◽  
Charpy Impact ◽  
Melting Process ◽  
Laser Melting ◽  
Average Impact ◽  
Before And After ◽  
The Impact

AbstractThis study manufactured Ti-6Al-4V alloy using one of the powder bed fusion 3D-printing processes, selective laser melting, and investigated the effect of heat treatment (650°C/3hrs) on microstructure and impact toughness of the material. Initial microstructural observation identified prior-βgrain along the building direction before and after heat treatment. In addition, the material formed a fully martensite structure before heat treatment, and after heat treatment,αandβphase were formed simultaneously. Charpy impact tests were conducted. The average impact energy measured as 6.0 J before heat treatment, and after heat treatment, the average impact energy increased by approximately 20% to 7.3 J. Fracture surface observation after the impact test showed that both alloys had brittle characteristics on macro levels, but showed ductile fracture characteristics and dimples at micro levels.

Impact Toughness of 0.3 Mass% Carbon Tempered Martensitic Steels Evaluated by Instrumented Charpy Test

2014 ◽  
Vol 783-786 ◽  
pp. 1033-1038
Author(s):  
Shigeto Takebayashi ◽  
Kohsaku Ushioda ◽  
Naoki Yoshinaga ◽  
Shigenobu Ogata
Keyword(s):  
Impact Toughness ◽  
Temperature Dependence ◽  
Impact Energy ◽  
Charpy Impact ◽  
Waveform Analysis ◽  
Charpy Impact Energy ◽  
Martensitic Steels ◽  
Tempering Temperature ◽  
Wide Range ◽  
The Impact

The effect of tempering temperature on the impact toughness of 0.3 mass% carbon martensitic steels with prior austenite grain (PAG) size of about 6 μm and 30 μm were investigated. Instrumented Charpy impact test (ICIT) method was used to evaluate the impact toughness. The tempering temperature of 723K gives the largest difference in the Charpy impact energy at room temperature (RT) between the specimens with two different PAG sizes. Investigation of the test temperature dependence of Charpy impact energy in the 723K tempered steels shows a steep transition at around 200 K for the 6 μm PAG specimen, while it shows a continuous slow transition in a wide range of temperature for the 60 μm PAG specimen. ICIT waveform analysis shows that the fracture propagation energy in stead of the fracture initiation energy mainly controls the temperature dependence of the impact energy. The carbide size distribution in these two specimens was investigated by SEM and TEM. The 60 μm PAG specimen shows the distribution of coarser carbides than does the 6 μm PAG specimen, which seems to be the main reason for the observed difference between them in the Charpy impact energy and the other properties of impact fracture.

scholarly journals Significant Influence of Welding Heat Input on the Microstructural Characteristics and Mechanical Properties of the Simulated CGHAZ in High Nitrogen V-Alloyed Steel

2020 ◽  
Vol 39 (1) ◽  
pp. 33-44
Author(s):  
Jing Zhang ◽  
Wenbin Xin ◽  
Guoping Luo ◽  
Ruifen Wang ◽  
Qingyong Meng
Keyword(s):  
Mechanical Properties ◽  
Impact Toughness ◽  
Heat Input ◽  
Prior Austenite ◽  
Alloyed Steel ◽  
Coarse Grained ◽  
High Nitrogen ◽  
Microstructural Characteristics ◽  
Welding Heat Input ◽  
The Impact

AbstractThe microstructural characteristics and mechanical properties of the simulated coarse grained heat affected zone (CGHAZ) in high N V-alloyed steel have been conducted under different welding heat input, characterized by the cooling time taken from 800°C to 500°C (t8/5). The experimental results show that the microstructure is dominantly composed of lath bainite (LB) and granular bainite (GB) at t8/5 30 s– 90 s. The content of LB decreases with t8/5 increasing, and that of GB increases. When t8/5 further increases to 120 s and 180 s, the microstructure mainly consists of intragranular polygonal ferrite (IPF) and acicular ferrite (IAF). The higher t8/5 leads to the increased content of intragranular ferrite (IGF). Meanwhile, the prior austenite grain size (PAGS) progressively increases from 56 ± 6.0 μm to 148 ± 9.9 μm as t8/5 increases from 30 s to 180 s. Besides, EBSD analysis indicates that the fraction of high angle grain boundaries (HAGBs) is 0.570, 0.427 and 0.624, respectively, corresponding to t8/5 30, 90 and 180 s. Moreover, the impact toughness decreases as t8/5 increases from 30 s to 90 s caused by the increased PAGS and GB content, and then sharply increases with t8/5 exceeding 90 s due to the increased formation of IGF, especially IAF. Furthermore, the high nitrogen content accelerates V(C,N) precipitation, which not only inhibits the coarsening of prior austenite grains, but promotes the formation of IGF, resulting in the increased number of HAGBs and raising impact toughness.

Bending and Tempering Process of L415M Hot Induction Bend Used in Low Temperatures Areas

2016 ◽  
Vol 850 ◽  
pp. 910-915
Author(s):  
Li Jun Yan ◽  
Yu Zhuo Li ◽  
Peng Zhu ◽  
Jia Shi ◽  
Jin Sheng Liu ◽  
...  
Keyword(s):  
Impact Toughness ◽  
Process Parameters ◽  
Impact Energy ◽  
Water Quenching ◽  
Granular Bainite ◽  
Temper Brittleness ◽  
Column Structure ◽  
Tempering Treatment ◽  
The Impact ◽  
Tempering Process

Test bends of L415M hot induction bend of 508 mm OD×14.3 mm WT used in –45°C areas were conducted. The bending and tempering process parameters were designed, the influences of bending and tempering process parameters on impact toughness at –45°C and microstructure of tangent weld and bend weld were investigated. Hot induction bend was produced by the process of local induction heating+fast water quenching. After tempering treatment, the weld contained martensite-austenite (M-A) islands, carbide precipitations, welded column crystal structure and little pearlite (P), and the brittle fracture surface contained S segregation, the temper brittleness of the weld occurred, which lead to impact energy of bend weld to be lower than 40 J at –45°C. Without post-bending tempering treatment, the microstructures of bend weld was a composite of polygonal ferrite (PF) and granular bainite (GB) with small size and uniform distribution, the coarse column structure and acicular ferrite (AF) disappeared in the weld, so the impact energy of bend weld was higher than 70 J at –45°C, but the impact energy of tangent weld was very poor. It suggests that the process of overall induction of heating + fast water quenching + no tempering treatment is more reasonable, the process ensures that the impact toughness at –45°C, strength and other properties of bend meet the requirements of CDP-S-OGP-PL-016-2011-2.

Effect of Trace Boron on Low Temperature Impact Toughness of Hot-Rolled Nb-Added HSLA H-Beams

2012 ◽  
Vol 174-177 ◽  
pp. 1030-1033 ◽  
Author(s):  
Guo Tao Cui ◽  
Zuo Cheng Wang ◽  
Tao Sun ◽  
Wei Min Guo ◽  
Jun Qing Gao
Keyword(s):  
Impact Toughness ◽  
Impact Energy ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
Total Oxygen ◽  
Transmission Electron ◽  
Temperature Impact ◽  
Low Temperature Impact Toughness ◽  
Hot Rolled ◽  
The Impact

In this research, trace boron (4ppm, 8ppm, 11ppm) was added into the Nb-added HSLA H-beams. The impact toughness of H-beams with/without boron was examined by Charpy impact test (V-notch). The morphologies of the microstructure and the fracture surfaces of the impact specimens were observed by metalloscope, stereomicroscope and electron probe. The experimental results prove that the absorbed impact energy at -40°C for the 4ppm, 8ppm, 11ppm boron-added steels respectively reaches up to 80J, 126J, 85J from 15J and H-beams with boron have a lower FATT than that without boron. It is also found that the total oxygen content affects the absorbed impact energy to a certain extent. It is discovered by transmission electron microscope (TEM) that boron mainly exists in solid solution state, except that a little amount of Fe23(C, B)6is formed at the grain boundaries, and the distribution of Nb(C, N) is also influenced by boron addition.

scholarly journals Research on Influential Mechanism of HAZ Impact Toughness for Shipbuilding Steel with Mg Addition

Metals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 584 ◽  
Author(s):  
Hui-rong Li ◽  
Li-gen Sun ◽  
Li-guang Zhu ◽  
Yun-song Liu ◽  
Yun-gang Li
Keyword(s):  
Impact Toughness ◽  
Heat Input ◽  
Steel Plates ◽  
Heat Affect Zone ◽  
Shipbuilding Steel ◽  
Welding Heat Input ◽  
Large Heat ◽  
Mg Addition ◽  
The Difference ◽  
The Impact

The welding performance of shipbuilding steel under large heat input could be improved greatly by the addition of Mg to the steel, but the impact toughness of the heat affect zone (HAZ) is not stable. According to the three different thickness steel plates obtained in the industrial experiment, the large heat input welding was carried out by different heat input, and the impact toughness analysis, impact fracture analysis, metallographic microstructure analysis and inclusions analysis were carried out. The results showed that, the HAZ of three kinds of thickness plates induced much intragranular acicular ferrite (IAF); with Mg addition, the inclusion dimension had been reduced effectively, and the IAF-induced ability of the inclusions had also been improved. The difference of HAZ impact toughness with different welding heat input and different impact temperature is significant; considering the influence of welding heat input and metallographic microstructure on the impact toughness of HAZ, the welding heat load had a far greater effect than the metallographic microstructure on ductile–brittle transition temperature. At the same time, if the original metallographic microstructure of steel was coarse, the pinning effect of the inclusions would be reduced significantly, and the microstructure of HAZ would be coarsened and the impact toughness of HAZ would be decreased, so there is a certain matching relationship between the metallographic microstructure and the inclusion dimension.

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