Effect of cooling rate on the structure and properties of low-carbon tube steel

Effects of boron in low-carbon tube steel grade 17G1SU on nonmetallic inclusions, structure and mechanical properties were investigated. Experimental samples of rolled metal containing boron 0.006 and 0.011% are characterized by predominantly small, nonmetallic inclusions not more than 5 μm, which are represented by complex alumomagnesium spinels in the shell of manganese and calcium sulfides, and small silicate inclusions. Nonmetallic inclusions of comparative pipe steel sample, containing no boron characterized by the presence of larger inclusions presented complex oxysulfide and sulfide films. The main structural component of the comparative and experimental samples is ferrite. The introduction of boron is contributed by a decrease in the average size of ferritic grains from 8.7 μm (0% B) to 6.2 (0.006% B). Increasing the boron content to 0.011% leads to slight increase (up to 6.8 microns) of the size. The mechanical properties of 10 μm rolled metal pipe steel ensured the production of rolled products of strength class X80 without additional (thermal) treatment, as a result of the reduction in the size and shape of nonmetallic inclusions, and formation of dispersed structure.

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The Effect of Mn Content on the Structure and Properties of PM Mn Steels

Archives of Metallurgy and Materials ◽

10.1515/amm-2017-0318 ◽

2017 ◽

Vol 62 (4) ◽

pp. 2153-2163

Author(s):

M. Tenerowicz ◽

M. Sułowski

Keyword(s):

Heat Treatment ◽

Cooling Rate ◽

Graphite Powder ◽

Strength Properties ◽

Structure And Properties ◽

Low Carbon ◽

Plastic Properties ◽

Closed Container ◽

Dog Bone ◽

Mn Content

AbstractThe aim of the study was to examine how a reduction of Mn content in PM steels will affect their plastic and strength properties. The results of mechanical, metallographic and fractography tests of sintered (PM) steels containing 1% and 2% Mn are reported and compared with those for 3% Mn PM steel. Höganäs iron powder grade NC 100.24, low-carbon ferromanganese Elkem and graphite powder grade C-UF were used as the starting powders. Powder mixes Fe-(1-2)%Mn-0.8%C were prepared in a Turbula mixer for 30 minutes. Following mixing, “dog bone” compacts were single pressed at 660 MPa, according to PN-EN ISO 2740 standard. Sintering of compacts was carried out in a laboratory tube furnace at 1120°C and 1250°C for 60 minutes in a mixture of 95%N2– 5%H2in a semi-closed container. Three types of heat treatment were then used: sinterhardening (cooling rate – 66°C/min), slow furnace cooling (cooling rate 3.5°C/min) and tempering at 200°C. The studies have shown a beneficial effect of the reduction of manganese on plastic properties (up to 7.96%), while maintaining fracture strengths (UTSs) comparable to those of steel with higher contents of manganese. Currently detailed studies of steel containing 1%Mn are conducted.

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Effect of cooling rate on structure and properties of an ultra-low carbon HSLA-100 grade steel

Materials Characterization ◽

10.1016/j.matchar.2005.09.014 ◽

2006 ◽

Vol 56 (1) ◽

pp. 59-65 ◽

Cited By ~ 34

Author(s):

A. Ghosh ◽

S. Das ◽

S. Chatterjee ◽

P. Ramachandra Rao

Keyword(s):

Cooling Rate ◽

Structure And Properties ◽

Low Carbon ◽

Grade Steel

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Structure and Properties of Autotempered Low Carbon Martensite

Strength of Metals and Alloys (ICSMA 7) ◽

10.1016/b978-0-08-031640-6.50032-3 ◽

1986 ◽

pp. 2099-2104 ◽

Cited By ~ 1

Author(s):

Qi Jingyuan

Keyword(s):

Structure And Properties ◽

Low Carbon ◽

Carbon Martensite

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

Metals ◽

10.3390/met9090939 ◽

2019 ◽

Vol 9 (9) ◽

pp. 939 ◽

Cited By ~ 1

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).

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Formation of Structure and Properties of Low-Carbon Pipe Steel with Ultralow Manganese Content during Thermomechanical Treatment

Metallurgist ◽

10.1007/s11015-021-01180-3 ◽

2021 ◽

Author(s):

L. I. Éfron ◽

E. A. Volkova ◽

D. V. Kudashov ◽

D. A. Ringinen ◽

O. A. Bagmet ◽

...

Keyword(s):

Thermomechanical Treatment ◽

Pipe Steel ◽

Manganese Content ◽

Structure And Properties ◽

Low Carbon

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A Comparative Study of Acicular Ferrite Transformation Behavior between Surface and Interior in a Low C–Mn Steel by HT-LSCM

Metals ◽

10.3390/met11050699 ◽

2021 ◽

Vol 11 (5) ◽

pp. 699

Author(s):

Xiaojin Liu ◽

Guo Yuan ◽

Raja. Devesh Kumar Misra ◽

Guodong Wang

Keyword(s):

Grain Boundaries ◽

Cooling Rate ◽

Acicular Ferrite ◽

Laser Scanning ◽

Sample Surface ◽

Surface Microstructure ◽

In Situ Observation ◽

Low Carbon ◽

Transformation Behavior ◽

Ferrite Transformation

In this study, the acicular ferrite transformation behavior of a Ti–Ca deoxidized low carbon steel was studied using a high-temperature laser scanning confocal microscopy (HT-LSCM). The in situ observation of the transformation behavior on the sample surface with different cooling rates was achieved by HT-LSCM. The microstructure between the surface and interior of the HT-LSCM sample was compared. The results showed that Ti–Ca oxide particles were effective sites for acicular ferrite (AF) nucleation. The start transformation temperature at grain boundaries and intragranular particles decreased with an increase in cooling rate, but the AF nucleation rate increased and the surface microstructure was more interlocked. The sample surface microstructure obtained at 3 °C/s was dominated by ferrite side plates, while the ferrite nucleating sites transferred from grain boundaries to intragranular particles when the cooling rate was 15 °C/s. Moreover, it was interesting that the microstructure and microhardness of the sample surface and interior were different. The AF dominating microstructure, obtained in the sample interior, was much finer than the sample surface, and the microhardness of the sample surface was much lower than the sample interior. The combined factors led to a coarse size of AF on the sample surface. AF formed at a higher temperature resulted in the coarse size. The available particles for AF nucleation on the sample surface were quite limited, such that hard impingement between AF plates was much weaker than that in the sample interior. In addition, the transformation stress in austenite on the sample surface could be largely released, which contributed to a coarser AF plate size. The coarse grain size, low dislocation concentration and low carbon content led to lower hardness on the sample surface.

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