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A Comprehensive Guide to 10# Steel

What is 10# steel?

10# steel is a high-quality carbon structural steel, its plasticity; toughness is very good, easy to hot and cold machining molding, normalizing or cold working cutting performance is good, and excellent weldability, no tempering brittleness, hardenability, and hardenability are poor.

20220815111302 27438 - A Comprehensive Guide to 10# Steel

Characteristics of 10# steel

10 # steel cold plasticity is good, plate by normalizing or high-temperature tempering performance is excellent, cold drawn normalized state than the annealed state of the chip performance is good, excellent weldability, no tempering brittleness, strength is slightly higher than the 08/08F steel, plasticity, toughness is very good, easy to its cold, hot processing molding, but the hardenability and hardenability are poor.

Chemical Composition of 10# steel

Chemical Element C Si Mn P S Cu Ni Cr
Minimum Value 0.07 0.17 0.35
Maximum Value 0.13 0.37 0.65 0.035 0.04 0.3 0.3 0.15

Mechanical Properties of 10# steel

  • Tensile strength σb (MPa): ≥335
  • Yield strength σs (MPa): ≥205
  • Elongation δ5 (%): ≥31
  • Sectional shrinkage ψ (%): ≥55.
  • Hardness: without heat treatment, ≤137HBs.
  • Specimen size: specimen size longitudinal 25mm

Creep limit, N/mm2, not less  Ultimate short-term tensile strength, not less Minimum elongation ratio, %, not less Contraction ratio, %, not less
 205 330 31 55

Heat Treatment Process Specification for 10 # Steel

Process name Normalizing High temperature tempering Quenching Carburization Quenching after carburization Tempering
Heating temperature/ 900-940 650-680 910-930 900-960 780-820 180-200
Cooling method Air cooling Air cooling Water and brine cooling Water-cooling Air cooling
Hardness ≤ 143HBW (<17HRC)

Uses of 10# steel

10# steel can be used in the manufacture of the requirements of the force is not high, high toughness parts, such as automobile bodies, receptacles, deep stamping vessels, tubes, gaskets, etc., can be used as cold rolled, cold punched, cold upsetting, cold bending, hot rolling and other processes such as molding, but also can be used as the heart of the strength of the carburization is not high, carbon-nitrogen infiltration parts, etc.

Effect of cold rolling deformation on microstructure and mechanical properties of 10# steel

10# steel is a high-quality carbon structural steel with good plasticity and toughness, and easy to form hot and cold machining; welding performance is excellent, suitable for the manufacture of force requirements are not high, high toughness parts, such as automobile bodies, deep stamping utensils, etc., usually using cold rolled, cold punched, hot rolled and other processes forming. Usually, low carbon steel is by the traditional heat treatment process to obtain the mechanical properties of low, and quenching + cold deformation can make low carbon steel obtain higher strength. 10 steel quenching to get completely martensitic organization, and then cold rolled deformation treatment, the hardness, and strength of the steel can significantly improve the mechanical properties of the index can reach the level of ultra-high-strength steel, so the 10 steel quenching + cold deformation treatment can be used as automotive High-strength steel material, has great market potential. Currently, some researchers have carried out research work on 10 steel, such as Wang Shuanglong and other research on the effect of annealing treatment on the microstructure and magnetic properties of 10 steel; the results for the annealing treatment of 10 steel can improve the organization of the inhomogeneity, optimize the carbide distribution, improve the magnetic properties of 10 steel. Zhao Tianlei et al. studied the corrosion electrochemical behavior of 10 carbon steel in NaOH solution; the results for the NaOH mass fraction ≤ 20%, 10 carbon steel formed by the passivation film is dense and complete, corrosion is light, the specimen over the passivation zone occurs pitting corrosion. NaOH mass fraction of ≥ 30%, the degree of pitting corrosion of 10 carbon steel significantly deepened. According to the published literature on 10 steel, the current research results on 10 steel quenching + cold rolling deformation aspects of the report have rarely been reported, so this paper to 10 steel as the object of study, focusing on the study of different cold rolling deformation on the quenched state of 10 steel microstructure and mechanical properties of the influence of the quenched state of 10 steel, for the further application of 10 steel to provide a reference.

1. Test materials and methods

The test material is selected from 10 steel plates with a thickness of 5mm, and its chemical composition is shown in Table 1.
Table.1 Chemical composition of test steel (mass fraction, %)

C Si Mn Cu Cr P S Fe
0.12 0.19 0.38 0.12 0.16 0.02 0.02 Allowance

The specimen with the size of 50mm×100mm×5mm was wire-cut from the test steel plate, and the specimen was first water-quenched by holding at 1150°C for 5min. Its SEM organization is shown in Fig. 1. As shown in Fig.1; the quenched test steel is organized as randomly oriented lath martensite.
20230711011458 88810 - A Comprehensive Guide to 10# Steel
Fig.1 SEM organization of quenched test steel
After the surface of the quenched specimen was polished and brightened with sandpaper, the multi-pass cold rolling test was carried out at room temperature with the rolling gauge of 5→4.5→3.6→2.4→2→1.2mm, and the rolling deflection of 10%, 28%, 52%, 60%, and 76%, respectively. Microscopic observation specimens were cut from different thicknesses of plates after rolling. The RD-ND sections of the specimens were hydro-ground and polished, corroded with 4% nitric acid alcohol solution, and the microstructure was observed by SIGMA500 scanning electron microscope. Tensile performance test by the requirements of the GB228-2002 standard, along the rolling direction of the plate, cut processing tensile specimens, specimen spacing 8mm, width 2mm, using WD-E100D universal testing machine to complete the tensile test. An HV-1000 micro-vickers hardness tester completes the hardness test. Impact performance test by GB/T229-2007 standards to produce U-type impact specimen, notch depth of 2mm, using JB-30B impact testing machine to complete the test.

2. Test results and analysis

2.1 The effect of deformation on the organization of the test steel

Figure 2 shows the SEM organization of the test steel under different deformation amounts. Figure 2 shows that the deformation is in the range of 10% -76%; with the increase of deformation, the test steel organization martensite gradually tends to the rolling direction, and along the rolling direction is constantly elongated grain refinement. Deformation of 60% of the test steel organization in the slat orientation and rolling direction nearly parallel to the slat spacing reduced the organization of defects significantly reduced. Deformation increased to 76%, the test steel organization in the martensite slats is no longer clear, and martensite presents obvious layering characteristics.
20230711011907 27939 - A Comprehensive Guide to 10# Steel
Figure.2 SEM organization of test steel with different deformation amounts

2.2 Effect of deformation amount on the properties of test steel

Figure 3 shows the mechanical property test results of the test steel under different deformation amounts. As can be seen from Fig.3, the hardness, tensile strength, yield strength, elongation, and impact toughness values of the quenched test steel are 437HV, 1295MPa, 1168MPa, 15.2%, and 91J/cm2, respectively. The hardness, tensile strength, yield strength, elongation, and impact toughness values of the cold rolled test steel with 28% of the deformation amount are 459HV, 1586MPa, the hardness, tensile strength, yield strength, elongation, and impact toughness values of the test steel were 459HV, 1586MPa, 1455MPa, 10.5% and 64J/cm2 for 28% deformation. 479HV, 1734MPa, 1588MPa, 8.6%, and 57J/cm2 were obtained for the test steel with different deformations than the test steel without cold rolling deformation. The hardness and strength of the cold rolled test steels with different amounts of deformation were increased to different degrees, while the elongation and impact toughness were decreased. Deformation in the range of 10% -76%, with the increase in deformation, the test steel hardness, strength gradually increased, elongation, and impact toughness gradually decreased, cold rolled deformation is 10 steel a suitable strengthening method. After cold rolling with different deformation, the test steel organization in the slat martensite migration led to interlocking, grain fragmentation, refinement, and cold work hardening effect. Hence, the test steel hardness and strength increased, and plasticity and toughness decreased.
20230711012437 43288 - A Comprehensive Guide to 10# Steel
Fig.3 Mechanical properties of test steel with different deformation amounts

2.3 Analysis of impact fracture morphology of test steel

Figure 4 shows the impact fracture morphology of the test steel under different deformation amounts. As can be seen from Fig. 4, the fracture of the test steel with 28% deformation has many densely distributed equiaxed ligamentous nests, and the size of the ligamentous nests is small. Compared with the test steel at 28% deformation, the number of ligament fossae at the fracture of the test steel at 52% deformation is reduced, the depth becomes shallow, the distribution is discrete, and the deconstructed step morphology appears. When the deformation amount reaches 76%, the number of axial ligament fossils in the fracture of the test steel is less, and a large number of shear ligament fossils appear. From the fracture morphology, it can be seen that with the increase of deformation, the toughness of the test steel gradually decreases.
20230711013527 13570 - A Comprehensive Guide to 10# Steel
Figure.4 Impact fracture morphology of test steel with different deformation amount

3. Conclusion

  • (1) Under the test conditions, the organization of quenched state 10 steel is slat martensite with random orientation. Within 10%-76%, with the increase of deformation, the martensite in the 10 steel organization gradually tends to be aligned in the rolling direction, along the rolling direction is continuously elongated, and the grain is gradually refined.
  • (2) With the increase of deformation, 10 steel hardness, strength gradually increased, elongation, and impact toughness gradually decreased, cold rolled deformation is 10 steel a suitable strengthening method. The hardness, tensile strength, and yield strength of 10 steel with 52% deformation reached 479HV, 1734MPa and 1588MPa, respectively.

Author: Kou Mingyun

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