Mechanical Properties Test Of Low Alloy Wear Resistant Steel For Bucket
1. Selection of test materials: three kinds of low alloy wear resistant steel for excavator bucket produced by IBC Group were selected for the test. The thickness of the materials is 45mm. And the chemical composition of the three steels is as follows:
| Chemical Composition Content | Steel A | Steel B | Steel C |
| C | 0.220 | 0.240 | 0.170 |
| Si | 0.330 | 0.270 | 0.270 |
| Mn | 0.660 | 1.110 | 1.370 |
| P | 0.009 | 0.011 | 0.014 |
| S | 0.001 | 0.022 | 0.004 |
| Cr | 0.500 | 0.190 | 0.390 |
| Mo | 0.013 | 0.022 | 0.033 |
| Nb | 0.020 | 0.025 | 0.021 |
| Ti | 0.003 | 0.023 | 0.023 |
| Al | 0.053 | 0.025 | 0.031 |
2. Test method
(1)Tensile test
In the tensile test, the steel is processed into a standard rectangle of 12.5mm×3.0mm×135mm. Three tests are conducted for each set of experiments. We use CMT5105 microcomputer control electronic universal testing machine to test the strain and tension of time. During the test, the stretching speed is 1mm/min. The results of the three measurements are averaged for each group.
(2)Impact test
Impact test The steel is processed into a standard V-shaped Charpy impact specimen of 10mmX10mm.X 55mm. ZBC2302-1 impact testing machine is used to measure the specimen. Impact absorption work after cooling in a liquid nitrogen test barrel at -20°C for 20min. The number of experiments is three. The experimenter will average the results of the three measurements.
(3)Abrasive wear test
In the abrasive wear test, we will process the steel into a 57mmX25.5mmX 6mm rectangular plate with a roughness of 6.3μm. The test is carried out on MLG-130 dry rubber abrasive wear testing machine. The wear surface is the surface of the steel plate. The speed of the rubber wheel is 200r/min, and the abrasive is 40~80 mesh quartz sand.
Analysis Of Experimental Results
1. Tensile test
The yield strength, tensile strength and elongation of high strength wear-resisting stiffness of three different low alloys show the same variation law. The tensile yield strength and tensile strength of steel A are the highest. Steel B is the second, steel C is the smallest. However, the elongation of steel C is the largest, reaching 110.4%. The elongation of steel A and steel B is similar, and the value is small, about 11%.
2. Impact test
Similar to the tensile test results of low-alloy high-strength wear-resistant steel, the impact absorption work of steel A is the largest, with an average value of 34.6J. The impact absorption work of steel B is the second, with an average value of 30.6J. The impact absorption work of steel C is the smallest with an average value of 14.0J.
3. Abrasive wear test
There are two different loading conditions in this test. Our experimentered conducted two sets of tests with 130N and 60N loads. Under the load of 130N, the grinding loss mass of steel C is the largest. Reach 6.05g; The grinding loss mass of steel B was the second, reaching 5.03g. Steel C has the smallest grinding loss mass, reaching 4. 54g.
In addition, under the load of 60N, the wear amount of steel C decreases significantly, while the wear amount of steel B and steel A change little. Steel C has the largest grinding loss mass, reaching 5.36g. The grinding loss mass of steel B was the second, reaching 5.22g. Steel C has the smallest grinding loss mass, reaching 4.69g.
According to the comprehensive analysis, steel C has the worst wear resistance, followed by steel B and steel A. Combined with the tensile strength test and impact test results of three low alloy wear resistant steels, steel A is determined as the optimal wear-resistant excavator bucket material.
Effect Of Different Alloyed Elements Combination On Low Alloy Wear Resistant Steel
(1) Function of metal elements Cr and Mo
Cr and Mo are two important elements that affect the wear resistance of low alloy steel used in excavator bucket. Cr element can improve the corrosion resistance of steel and reduce the friction coefficient, thus improving the wear resistance. The addition of Mo to low alloy steel can increase its strength, toughness and heat resistance. Mo elements have a positive impact on the wear resistance of steel. It can enhance the ability of anti-abrasive wear of steel.
(2)Set the combined working condition of Cr and Mo elements
Based on the above analysis, we set three different combinations of alloyer elements Cr and Mo for steel A. The increment of metal element Cr is 0.15%, the increment of metal element Mo is 0.003, and the content of other elements remains unchanged, as shown in the following table.
| Chemical Composition Content | C | Si | Mn | P | S | Cr | Mo | Nb | Ti | Al |
| A | 0.22 | 0.33 | 0.66 | 0.009 | 0.001 | 0.35 | 0.010 | 0.02 | 0.003 | 0.053 |
| B | 0.22 | 0.33 | 0.66 | 0.009 | 0.001 | 0.50 | 0.013 | 0.02 | 0.003 | 0.053 |
| C | 0.22 | 0.33 | 0.66 | 0.009 | 0.001 | 0.70 | 0.016 | 0.02 | 0.003 | 0.053 |
(3)Hardenability analysis under different working conditions
The tensile strength, yield strength and hardness of steel under three different working conditions show the same change law. As the distance from the surface increases, the tensile strength, yield strength and hardness all show an inverse “S” curve pattern. .
Among them, the tensile strength range of working condition A is 646~1120MPa, the yield strength is 891~1374MPa, and the hardness is 26~44HRC. In case B, the tensile strength ranges from 710 to 1232MPa, the yield strength ranges from 980 to 1152MPa, and the hardness ranges from 29 to 49HRC. In condition C, the tensile strength ranges from 746 to 1293MPa, the yield strength from 1029 to 1587MPa, and the hardness from 30 to 51HRC.
In conclusion, the tensile strength, yield strength and hardness of the steel are increasing with the increase of the content of alloy elements Cr and Mo. Therefore, we can determine that in steel A, the optimal content of metal elements Cr and Mo is 0.70%he 0.016%, respectively.
Conclusion
The main ergonomic component of the excavator is the bucket. In the process of direct contact with rock and soil, the excavator bucket often wears out. Based on this, this study found that low alloy wear resistant steel with low alloy content and good hardness and toughness is one of the effective means to ensure the bucket resistance to impact and improve the wear-resisting effect.
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