Factors affecting heat-resistant castings

- Nov 10, 2019-

1) Effect of chemical composition on service life of heat-resistant steel

There are quite a few types of chemical elements that can affect the service life of heat resistant steel. These effects are manifested in enhancing the stability of the structure, preventing oxidation, forming and stabilizing austenite, and preventing corrosion. For example, rare earth elements as trace elements in heat-resistant steel can significantly improve the oxidation resistance of steel. Thermoplastic. The basic materials of heat-resistant steel and alloy generally use metals and alloys with relatively high melting point and high self-diffusion activation energy or low stacking fault energy. The requirements for smelting processes in various heat-resistant steels and superalloys are very high, because once the inclusions or some metallurgical defects in the steel are present, the ultimate strength limit of the material is lowered. Therefore, research on the role of chemical substances is also of far-reaching significance.

2) Influence of laser shock on service life of heat-resistant steel

The heat-resistant steel sample was subjected to laser shock tempering treatment by 00Cr12, and then subjected to fatigue tensile test under conditions of 25, 400, 500 and 600 degrees Celsius, and tested to test heat-resistant steel at different temperatures. The mechanical properties of the sample. Using the one-sided tolerance factor method and the two-dimensional Weibull distribution method to estimate and compare the fatigue safety life, it can be found that the yield strength and elastic modulus of the sample after laser strengthening are obviously improved, and with the increase of temperature. increase. Temperature has a great influence on the life of heat-resistant steel, and the fatigue life is significantly reduced as the temperature increases. Laser technology is the most effective way to improve the fretting fatigue resistance of materials under normal temperature conditions in recent years.

3) Influence of advanced processes such as modification treatment and solution treatment on the service life of heat-resistant steel

The characteristics of inclusions, grain thickness and brittle phase in the castings were studied. The chemical composition, modification treatment, heat treatment and metal casting of ZG0Cr23Ni13 heat-resistant steel were studied. After complicated tests, statistics and comparisons, it can be concluded that advanced processes such as composite modification, metal casting, solution treatment and vacuum melting are beneficial to improve the normal temperature, high temperature mechanical properties and thermal fatigue resistance. Due to the refinement of crystal grains, the elimination of brittle phase network structure and the improvement of inclusion morphology and distribution. For metal materials, the use of different heat treatment processes will affect the structure and grain size, thus changing the ease of thermal activation. In the analysis of casting failure, there are many factors leading to failure, mainly due to thermal fatigue leading to crack initiation and development. Correspondingly, a series of factors affect the initiation and expansion of cracks. Among them, the sulfur content is extremely important because the cracks are mostly developed along the sulfide. The sulfur content is affected by the quality of the raw materials and its smelting. Castings working under the protective atmosphere of hydrogen, if hydrogen sulfide is contained in the hydrogen, will cause the castings to sulphur. Secondly, the adequacy of the solution treatment will affect the toughness of the casting.https://www.wuxiorient.com/