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.

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.

scholarly journals Evaluation of Microstructure and Impact Toughness of Shielded Metal Arc Dissimilar Weldments of High Strength Low Alloy Steel and Austenitic Stainless Steel

2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Misbahu A Hayatu ◽  
Emmanuel T Dauda ◽  
Ola Aponbiede ◽  
Kamilu A Bello ◽  
Umma Abdullahi
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Impact Toughness ◽  
Impact Energy ◽  
High Strength ◽  
Impact Testing ◽  
Welding Parameters ◽  
Dissimilar Weld ◽  
Weld Joints ◽  
The Impact

There is a growing interest for novel materials of dissimilar metals due to higher requirements needed for some critical engineering applications. In this research, different dissimilar weld joints of high strength low alloy (HSLA) and 316 austenitic stainless steel grades were successfully produced using shielded metal arc welding (SMAW) process with 316L-16 and E7018 electrodes. Five variations of welding currents were employed within the specified range of each electrode. Other welding parameters such as heat inputs, welding speeds, weld sizes, arc voltages and time of welding were also varied. Specimens for different weld joint samples were subjected to microstructural studies using optical and scanning electron microscopes. The impact toughness test was also conducted on the samples using Izod impact testing machine. The analysis of the weld microstructures indicated the presence of type A and AF solidification patterns of austenitic stainless steels. The results further showed that the weld joints consolidated with E7018 electrode presented comparatively superior impact energy to the weldments fabricated by 316L-16 electrode. The optimum impact energy of E7018-weld joints (51J) was attained at higher welding heat inputs while that of 316L-16-weld joints (35J) was achieved at lower welding heat inputs, which are necessary requirements for the two electrodes used in the experiment. Hence, the dissimilar weld joints investigated could meet requirement for engineering application in offshore and other critical environments.Keywords—Dissimilar metal weld, heat input, impact toughness, microstructures

Effect of Tempering Time on Microstructure and Mechanical Properties of SA738 Gr.B Steel

2021 ◽  
Vol 1016 ◽  
pp. 1739-1746
Author(s):  
Yan Mei Li ◽  
Shu Zhan Zhang ◽  
Zai Wei Jiang ◽  
Sheng Yu ◽  
Qi Bin Ye ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Impact Toughness ◽  
Yield Strength ◽  
Microstructure Evolution ◽  
Impact Energy ◽  
Nuclear Power ◽  
Microstructure And Mechanical Properties ◽  
The Impact ◽  
Tempering Time

The effect of tempering time on the microstructure and mechanical properties of SA738 Gr.B nuclear power steel was studied using SEM, TEM and thermodynamic software, and its precipitation and microstructure evolution during tempering were clarified. The results showed that SA738 Gr.B nuclear power steel has better comprehensive mechanical properties after tempering at 650 °C for 1h. With the extension of the tempering time, M3C transformed into M23C6 with increasing size, which affected the yield strength and impact energy. When the tempering time is 8h ~ 10h, due to the transformation of M3C to M23C6, the composition of matrix around the carbide changed, causing the temperature of Ac1 dropped, forming twin-martensite which deteriorated the impact toughness of the steel.

Mechanical Properties of Girth Weld with Different Butt Materials Severed for Natural Gas Station

2019 ◽  
Vol 944 ◽  
pp. 821-827
Author(s):  
Jun Jie Ren ◽  
Wei Feng Ma ◽  
Xue Liang He ◽  
An Qi Chen ◽  
Jin Heng Luo ◽  
...  
Keyword(s):  
Impact Toughness ◽  
Wall Thickness ◽  
Impact Energy ◽  
Weld Seam ◽  
Coarse Grained ◽  
Lower Grade ◽  
Straight Pipe ◽  
Bending Load ◽  
Girth Welds ◽  
The Impact

Weld samples imitating the inservice girth welds in station (L245 straight pipe jointed to WPHY-70 tee joint and L415MB straight pipe jointed to WPHY-80 tee joint) were prepared. Tensile, bending, impact toughness and hardness of the joints were investigated. Results show that under tensile or bending load, failure occurred from the side with lower grade and smaller wall thickness. Relatived to the lower grade side, the weld seam is strong match. Significant change of impact toughness can be found in weld seam center and the heat affected zones (HAZ). The impact energy of seam center is the lowest in the weld joint. The impact energy show a trend of increase from seam center to base metal. In HAZ zone, impact toughness of the fusion line is the lowest. Impact toughness of higher grade side is higher than that of the lower grade side. Hardness of positions in HAZ zones are different distinctly. From coarse grained region to fine grained region, the hardness decrease. For the in-station girth welds jointed with different materials, lower grade and samller wall thickness side should be intensive monitored.

Quench Brittleness of 12%Cr Martensitic Heat-Resistant Steel

2011 ◽  
Vol 479 ◽  
pp. 8-12 ◽  
Author(s):  
Gang Yang ◽  
Zheng Dong Liu ◽  
Shi Chang Cheng ◽  
Mu Xin Yang
Keyword(s):  
Impact Toughness ◽  
Cooling Rate ◽  
Microstructural Characterization ◽  
Temper Brittleness ◽  
Resistant Steel ◽  
Slow Cooling ◽  
Continuous Precipitation ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
The Impact

The mechanism of brittleness due to slow cooling during quenching was experimentally investigated in 12% Cr martensitic heat resistant steel. The mechanical property tests and microstructural characterization by SEM、TEM and XRD were conducted. The results showed the impact toughness would decrease with the slowing of cooling rate during quenching, and the low cooling rate within the temperature range from 820 to 660 °C played a significant effect on the impact toughness . Different from the mechanism of temper brittleness, the main causes of embrittlement due to the slow cooling upon quenching were both the continuous precipitation of M23C6 along prior austenite grain boundaries during the process of slow cooling and that of M2C along prior residual austenite film during tempering, and this kind of quench brittleness was nonreversal.

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 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.

scholarly journals On the Determining Role of Texture in Causing Delamination During Impact Fracture of Ti and Nb-Ti Microalloyed Steel

2019 ◽  
Author(s):  
Mingyu Sun ◽  
Xuemin Wang ◽  
R.D.K. Misra
Keyword(s):  
Impact Toughness ◽  
Fracture Surface ◽  
Impact Energy ◽  
Cleavage Fracture ◽  
Microalloyed Steel ◽  
Microalloyed Steels ◽  
Brittle Transition ◽  
High Toughness ◽  
The Impact

700 MPa grade Ti and Nb-Ti microalloyed steels produced by thermo-mechanical control rolled processes (TMCP) were studied to elucidate texture that contributes to delamination and consequent impact toughness. The microstructure of Ti and Nb-Ti steels consisted of ferrite and bainite. Compared with Ti steel, Nb-Ti steel was characterized by a microstructure with finer ferrite and more bainite. The results from tensile and impact tests indicated that there is insignificant change in tensile properties, but toughness was greater in Nb-Ti steel compared with Ti steel. More severe delamination in Nb-Ti steel is attributed to stronger α-fiber (RD ||<110>) texture than Ti steel, especially {100}<110>, {113}<110> and {112}<110> texture. Typical cleavage river patterns were not observed on delaminated fracture surface, instead the cleavage fracture surface indicated some dimples. Interestingly, the impact energy of samples with delamination was greater than samples without delamination in the ductile–brittle transition region. The study suggests that delamination in the ductile–brittle transition zone may also be representative of high toughness.

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.

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