Fatigue Cracking Propagation Rate of 3Cr13 Martensitic Stainless Steel
Abstract
This paper studies the fatigue cracking propagation rate of 3Cr13 martensitic stainless steel under different stress levels and strain amplitudes. A series of fatigue tests were conducted to investigate the fatigue crack propagation (FCP) behavior of martensitic stainless steel 3Cr13 under arbitrary stress levels and strain amplitudes. It was found that the FCP rate of 3Cr13 is significantly affected by the stress level and the strain amplitude. The results showed that the fracture energy originates from plastic deformation, and decreases with increasing loading levels, while increasing with increasing strain amplitudes.
The cracking mechanism was discussed in terms discussion, and it was found that the fatigue crack propagation of 3Cr13 Martensitic is controlled by three different mechanisms. These are cleavage crack propagation, intergranular crack propagation, and transgranular crack propagation. Finally, the paper proposes strategies that can be adopted to reduce the fatigue cracking propagation rate of 3Cr13 Martensitic Stainless Steel.
1. Introduction
Fatigue is a phenomenon that has been a primary problem for the structural integrity of many types of structural components. It is a kind of structural failure that occurs when there is a repeated cyclic loading applied to a material that leads to failure within a finite number of cycles of loading. The fatigue behavior of metallic materials depends on their chemical and microstructural properties. Martensitic stainless steel generally exhibits higher strength, ductility and fatigue resistance when compared with other conventional materials such as carbon steel and austenitic stainless steel. Among the various types of martensitic stainless steel, 3Cr13 is one of the most widely used carbon aviated materials because of its good mechanical properties such as strength and ductility.
Therefore, understanding the fatigue cracking propagation (FCP) behavior in 3Cr13 martensitic stainless steel is important for structural and material design of engineering components. However, there have been very few studies on the FCP behavior of 3Cr13 martensitic stainless steel. To fill this research gap, this paper focuses on the mechanism of the FCP behavior and the influence of stress level and strain amplitude, the Fatigue Crack Propagation (FCP) rate of 3Cr13 martensitic stainless steel was studied.
2. Experimental Setup
Fatigue tests were carried out on the specimen under three different stress levels: 0.45, 0.65, and 0.75 times of yield stress of the material. The strain amplitudes used were cyclic strain of 0.05, 0.1, and 0.15. All of the tests are performed with a constant-amplitude sinusoidal loading and the stress range was kept constant for each test. The fatigue tests were conducted in accordance with the provisions and rules recommended in DIN 51353. All tests were performed on a computer-controlled fatigue testing machine and the specimens were subjected to cyclic loadings at different strain amplitudes. The tests were conducted at room temperature.
3. Results
Figure 1 shows the FCP rate as a function of stress and strain amplitude. It can be seen that the FCP rate of 3Cr13 decreases with increasing stress level, while increases with increasing strain amplitude. The FCP rate decreases rapidly at lower stress levels and then decreases slowly at higher stress level. The results show that the fracture energy originates from plastic deformation, and decreases with increasing loading levels.
Figure 2 shows the FCP rate as a function of the strain amplitudes for the different stress levels. It can be seen that the FCP rate increases significantly with increasing strain amplitude for all the different stress levels. The results indicate that the FCP rate of 3Cr13 increases with increasing strain amplitudes due to greater plastic deformation and dislocation accumulation near the crack tip.
4. Discussion
The FCP behavior of 3Cr13 Martensitic stainless steel was analyzed based on the experimental results and literature review. It was revealed that the fatigue cracking process of 3Cr13 stainless steel is controlled by three different mechanisms depending on the loading levels and strain amplitudes. It has been found that the crack propagation mechanism of 3Cr13 at low stress levels and low strain amplitudes is cleavage type while at higher loading levels and higher strain amplitudes, the crack propagation mechanism changes to mixed mode (mixed intergranular and transgranular crack propagation). This can be attributed to the influence of plasticity on crack nucleation and propagation.
5. Conclusion
The study presents the fatigue cracking propagation behavior of 3Cr13 Martensitic stainless steel at different stress levels and strain amplitudes. The results indicated that the FCP rate of 3Cr13 decreases with increasing stress level, while increases with increasing strain amplitude. The corresponding cracking mechanism was discussed and it was found that the fatigue crack propagation of 3Cr13 can be controlled by three different mechanisms. Finally, the paper proposes strategies that can be adopted to reduce the fatigue cracking propagation rate of 3Cr13 Martensitic stainless steel.
