Mechanism of Decrease in Impact Toughness in a Low-Carbon MnCrMoNiCu Plate Steel with Increasing Austenitizing Temperature

2018 ◽  
Vol 27 (9) ◽  
pp. 4855-4870 ◽  
Author(s):  
Mi Luo ◽  
Dongsheng Liu ◽  
Binggui Cheng ◽  
Rui Cao ◽  
Jianhong Chen
Keyword(s):  
Impact Toughness ◽  
Plate Steel ◽  
Low Carbon ◽  
Austenitizing Temperature

Reasons for the formation of crack-like defects in 09Г2С heavy plate steel for tank steel structures

2020 ◽  
Vol 10 (5) ◽  
pp. 479-489
Author(s):  
Vitaly М. Goritsky ◽  
◽  
Georgy R. Shneyderov ◽  
Eugeny P. Studenov ◽  
Olga A. Zadubrovskaya ◽  
...  
Keyword(s):  
Impact Toughness ◽  
Defect Formation ◽  
Steel Structures ◽  
Controlled Rolling ◽  
Plate Steel ◽  
Heavy Plate ◽  
Oil Storage ◽  
Magnetic Inspection ◽  
Metal Microstructure

Determination of causes of crack-like defects in the heavy plate steel 09Г2С is a crucial task, the solution of which is aimed at improving the mechanical safety of oil storage steel vertical tanks. In order to determine the causes for the formation of a group of crack-like defects oriented towards rolling, revealed during grinding and magnetic inspection of the tank wall surface near the vertical weld, the analysis of the chemical composition and testing of the mechanical properties of heavy plate steel were carried out, including the determination of the anisotropy of impact toughness in the temperature range from +20 to –75 °С, analysis of metal microstructure in the area of defect formation on transversal sections and rolled surface. Impact bending tests of 09Г2С heavy plate steel after controlled rolling in longitudinal and transverse directions showed no anisotropy of impact toughness, as well as high purity of steel as for sulfur and titanium, which at higher content causes impact toughness anisotropy. The revealed features of metal microstructure near the defects made it possible to conclude that the crack-like defects were formed during the rolling of gas bubbles at the stage of preparing semi-finished rolled products for finishing rolling. One of the possible methods to prevent such defects from getting into finished rolled products is the use of automated systems of visual inspection of rolled products in the manufacturing process.

INVESTIGATION OF THE TOUGHNESS OF LOW CARBON TEMPERED MARTENSITE IN THE SURFACE OF Ni--Cr--Mo--B ULTRA--HEAVY PLATE STEEL

2013 ◽  
Vol 48 (4) ◽  
pp. 401-406 ◽  
Author(s):  
Xiaoyong WANG ◽  
Tao PAN ◽  
Hua WANG ◽  
Hang SU ◽  
Xiangyang LI ◽  
...  
Keyword(s):  
Plate Steel ◽  
Low Carbon ◽  
Tempered Martensite ◽  
Heavy Plate

scholarly journals Continuous Cooling Transformation Diagram, Microstructures, and Properties of the Simulated Coarse-Grain Heat-Affected Zone in a Low-Carbon Bainite E550 Steel

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 939 ◽  
Author(s):  
Yun Zong ◽  
Chun-Ming Liu
Keyword(s):  
Impact Toughness ◽  
Cooling Rate ◽  
Vickers Hardness ◽  
Heat Affected Zone ◽  
Granular Bainite ◽  
Coarse Grain ◽  
Low Carbon ◽  
Transformation Diagram ◽  
Lath Bainite ◽  
Continuous Cooling Transformation Diagram

In order to provide important guidance for controlling and obtaining the optimal microstructures and mechanical properties of a welded joint, the continuous cooling transformation diagram of a new low-carbon Nb-microalloyed bainite E550 steel in a simulated coarse-grain heat-affected zone (CGHAZ) has been constructed by thermal dilatation method in this paper. The welding thermal simulation experiments were conducted on a Gleeble-3800 thermo-mechanical simulator. The corresponding microstructure was observed by a LEICA DM2700M. The Vickers hardness (HV) and the impact toughness at −40 °C were measured according to the ASTM E384 standard and the ASTM E2298 standard, respectively. The experimental results may indicate that the intermediate temperature phase transformation of the whole bainite can occur in a wide range of cooling rates of 2–20 °C/s. In the scope of cooling rates 2–20 °C/s, the microstructure of the heat-affected zone (HAZ) mainly consists of lath bainite and granular bainite. Moreover, the proportion of lath bainite increased and granular bainite decreased as the cooling rate increasing. There is a spot of lath martensite in the microstructure of HAZ when the cooling rate is above 20 °C/s. The Vickers hardness increases gradually with the increasing of the cooling rate, and the maximum hardness is 323 HV10. When the cooling time from 800 °C to 500 °C (t8/5) is 5–15 s, it presents excellent −40 °C impact toughness (273–286 J) of the CGHAZ beyond the base material (163 J).

Effects of Al, Si and N Content on the Formation of M-A Constituent and HAZ Toughness of Ti-Containing Low-Carbon Steel

2021 ◽  
Vol 1016 ◽  
pp. 42-49
Author(s):  
Kook Soo Bang ◽  
Joo Hyeon Cha ◽  
Kyu Tae Han ◽  
Hong Chul Jeong
Keyword(s):  
Carbon Steel ◽  
Impact Toughness ◽  
Low Carbon Steel ◽  
Charpy Impact ◽  
Coarse Grained ◽  
Low Carbon ◽  
N Content ◽  
Si Content ◽  
The Impact ◽  
Haz Toughness

The present work investigated the effects of Al, Si, and N content on the impact toughness of the coarse-grained heat-affected zone (CGHAZ) of Ti-containing low-carbon steel. Simulated CGHAZ of differing Al, Si, and N contents were prepared, and Charpy impact toughness was determined. The results were interpreted in terms of microstructure, especially martensite-austenite (M-A) constituent. All elements accelerated ferrite transformation in CGHAZ but at the same time increased the amount of M-A constituent, thereby deteriorating CGHAZ toughness. It is believed that Al, Si, and free N that is uncombined with Ti retard the decomposition of austenite into pearlite and increase the carbon content in the last transforming austenite, thus increasing the amount of M-A constituent. Regardless of the amount of ferrite in CGHAZ, its toughness decreased linearly with an increase of M-A constituent in this experiment, indicating that HAZ toughness is predominantly affected by the presence of M-A constituent. When a comparison of the effectiveness is made between Al and Si, it showed that a decrease in Si content is more effective in reducing M-A constituents.

Effect of Ti, Al and Mg Addition on the Impact Toughness of Heat Affected Zone in Low Carbon Steel

2009 ◽  
Vol 79-82 ◽  
pp. 143-146
Author(s):  
Jiang Hua Ma ◽  
Dong Ping Zhan ◽  
Zhou Hua Jiang ◽  
Ji Cheng He
Keyword(s):  
Carbon Steel ◽  
Impact Toughness ◽  
Heat Affected Zone ◽  
Low Carbon Steel ◽  
Optical Microscope ◽  
Carbon Steels ◽  
Low Carbon ◽  
Welding Simulation ◽  
Mg Addition ◽  
The Impact

In order to understand the effects of deoxidizer such as aluminium, titanium and magnesium on the impact toughness of heat affected zone (HAZ), three low carbon steels deoxidized by Ti-Al, Mg and Ti-Mg were obtained. After smelting, forging, rolling and welding simulation, the effects of Al, Ti and Mg addition on the impact toughness of HAZ in low carbon steel were studied. The inclusion characteristics (size, morphology and chemistry) of samples before welding and the fracture pattern of the specimens after the Charpy-type test were respectively analyzed using optical microscope and scanning electron microscopy (SEM). The following results were found. The density of inclusion in Ti-Mg deoxidized steel is bigger than Ti-Al deoxidized steel. The average diameter is decreased for the former than the latter. The addition of Ti-Mg can enhance the impact toughness of the HAZ after welding simulation. The maximal value of the impact toughness is 66.5J/cm2. The complex particles of MgO-TiOx-SiO2-MnS are most benefit to enhance impact toughness. The improvement of HAZ is attributable to the role of particle pinning and the formation of intergranular ferrite.

Effect of Austenitizing Temperature and Air Cooling Rate on Microstructure and Properties of the Low Carbon Mn-Si-Cr Steel

2008 ◽  
Vol 33-37 ◽  
pp. 527-532
Author(s):  
Dong Yu Liu ◽  
Shi Xiang Hou ◽  
Ye Yuan ◽  
Bing Zhe Bai ◽  
Zong De Liu ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Charpy Impact ◽  
Optical Microscope ◽  
Experimental Result ◽  
Air Cooling ◽  
Low Carbon ◽  
Austenitizing Temperature ◽  
Austenite Grain Size ◽  
Hardness Tester ◽  
Mixed Microstructure

The air cooling rate of the Low Carbon Mn-Si-Cr steel bar with different diameter after austenitizing at 910oC and 960oC was simulated by Formaster-F Phase transforming instrument and Gleeble-1500 thermal /mechanical simulating machine. Microstructure of the specimen was observed by OLYMPUS PME3 optical microscope and FEI QUANTA200F scanning electron microscope. The hardness and impact toughness of the steel was tested by HBRV-187.5 hardness tester and JCSJ300-I instrumented Charpy impact tester. The experimental result showed that with the amount of CFB in CFB+M mixed microstructure increasing the combination of strength and toughness of the steel was improved. The higher the austenitizing temperature of the steel, the wider the air-cooling rate range obtaining CFB+M mixed microstructure. However, the steel produces mixed grain after austenitizing at 960 oC. For obtaining fine prior austenite grain size, Ti and Nb alloying element need to be added.

Effect of nickel on the impact toughness of weld metal with a low-carbon martensitic structure

1989 ◽  
Vol 3 (2) ◽  
pp. 147-149 ◽  
Author(s):  
A S Tabatchikov ◽  
T I Tabatchikova ◽  
A V Pryakhin
Keyword(s):  
Impact Toughness ◽  
Weld Metal ◽  
Martensitic Structure ◽  
Low Carbon ◽  
The Impact

Hardness and Impact Toughness of Niobium Alloyed Austempered Ductile Iron

2011 ◽  
Vol 418-420 ◽  
pp. 1768-1771 ◽  
Author(s):  
Bulan Abdullah ◽  
Siti Khadijah Alias ◽  
Ahmed Jaffar ◽  
Rashiddy Wong Freddawati ◽  
A. Ramli
Keyword(s):  
Impact Toughness ◽  
Ductile Iron ◽  
Treatment Process ◽  
Impact Test ◽  
Induction Furnace ◽  
Hardness Test ◽  
Austempered Ductile Iron ◽  
Austenitizing Temperature ◽  
Austempering Temperature ◽  
The Impact

The effect of different austempering holding times on the hardness and impact toughness of 0.254% niobium alloyed austempered ductile iron was investigated in this study. Molten ductile iron was prepared in an induction furnace with capacity of 60kg. Samples with dimension of 300m x Ø25mm in form of Y block double cylinder was constituted and solidified samples were then machined in accordance to ASTM E23 for impact test specimens. Samples were ground and polished before Rockwell hardness test was conducted. Austempering heat treatment process with austenitizing temperature of 900°C for 1 hour and austempering temperature of 350°C for 1 hour, 2 hours and 3 hour holding times were then carried out. The results from this research indicated that austempering the sample for 1 hour resulted in significant improvement of the impact toughness values but increasing the austempering holding time deficiently reduced the values. On the contrary, the hardness of niobium alloyed austempered ductile iron continues to increase with respect to longer austempering holding times.

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