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Product Details:
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| OD: | 6-600MM | Surface: | Black And Bright |
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| Type: | Hot Rolled And Cold Drawn | Condition: | Heat Treatments |
| Length: | 3-12m | ||
| High Light: | forged steel round bar,bright steel round bar |
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The failure cause of the 18CrNi3Mo steel for drilling bit, including inclusions, prior austenite grain size, carburized layers, and morphology of the fatigue fracture, was investigated by optical microscope, quantitative metallography, and scanning electron microscope. Results show that the failure of the drill bit is not related to interior inclusions or the inhomogeneity of the prior austenite grain size distribution. The failure is related to geometrical discontinuities causing stress concentration along the tooth profiles while under effect of continuous twisting and axial impact. Thus, the crack initiates in these areas, and the microstructures of the carburized layer, the transitive layer, and the matrix are all tempered martensite such that the crack propagation cannot be effectively restrained and the crack propagates quickly, causing premature failure of the drilling bit.
18CrNi3Mo steel Failure analysis Fracture Fatigue crack
| Grade : | 18CrNiMo7-6 | |
| Number: | 1.6587 | |
| Classification: | Alloy special steel | |
| Standard: |
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| Equivalent grades: | Go here |
Chemical composition % of steel 18CrNiMo7-6 (1.6587): EN 10084-2008
| Elements not quoted in this table shall not be intentionally added to the steel without the agreement of the purchaser, other than for the purpose of finishing the heat. Steels with improved machinability as a result of the addition of lead or higher sulfur contents, depending on the manufacturing process up to around 0.1 % S, may be supplied on request. In this case, the upper limit of the manganese content may be increased by 0.15 % |
| C | Si | Mn | Ni | P | S | Cr | Mo |
| 0.15 - 0.21 | max 0.4 | 0.5 - 0.9 | 1.4 - 1.7 | max 0.025 | max 0.035 | 1.5 - 1.8 | 0.25 - 0.35 |
Mechanical properties of steel 18CrNiMo7-6 (1.6587)
| Nominal thickness (mm): | to 16 |
| Rm - Tensile strength (MPa) hardening and tempering at 200 | 1200 |
| Brinell hardness (HBW): (+S) | 255 |
| Brinell hardness (HBW): (+A) | 229 |
| Brinell hardness (HBW): (+TH) | 179 - 229 |
| Brinell hardness (HBW): (+FP) | 159 - 207 |
Equivalent grades of steel 18CrNiMo7-6 (1.6587)
Warning! Only for reference
| EU EN | Germany DIN,WNr | France AFNOR | England BS | Italy UNI | China GB | Finland SFS | Inter ISO | ||||||||
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Post free buying requirement of steel 18CrNiMo7-6 (1.6587)
Mechanical properties
| ReH | Minimum yield strength / Mindestwert der oberen Streckgrenze / Limite d elasticite minimale |
| Rm | Tensile strength / Zugfestigkeit / Resistance a la traction |
| A | Minimum elongation / Mindestwert der Bruchdehnung / Allongement minimal |
| J | Notch impact test / Kerbschlagbiegeversuch / Essai de flexion par choc |
Heat treatment conditions
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Alloy special steel |
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