What is the temperature tolerance limit of 15CrMoR steel plates?℃
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Our reactor is made of 15CrMoR material. The reactor experienced a temperature spike, reaching up to 1000°C. What effects does this temperature have on the reactor? Moreover, the thermocouple sheath in the reactor is made of 0Cr18Ni10Ti material; what impact does this temperature have on it? I hope experts can provide an answer! !
This post was last edited by 413343962 on 2016-7-25 at 16:44. I don’t understand such complex material-related questions; I hope someone more knowledgeable can answer them. All I know is that for pressure vessels, the recommended operating temperature for 15CrMoR should not exceed 500 degrees Celsius; equipment operating at 1000 degrees Celsius is at risk ； If it is a reactor at atmospheric pressure, equipment at 1000 degrees Celsius would also be dangerous. 0Cr18Ni10Ti is prone to oxidation at 1000 degrees Celsius.
The device is basically damaged and can no longer be used.
According to the provisions of GB150.2-2011, for 15CrMoR, the maximum temperature at which high-temperature creep strength can be maintained for 100,000 hours is 550°C; 0Cr18Ni10Ti, which is equivalent to S30408, has a maximum temperature of 700°C for high-temperature creep strength over 100,000 hours. Without considering the effects of medium and pressure, if the reactor temperature rises to 1000°C, it can directly lead to material degradation. According to GB/T30579-2014, 15CrMoR is prone to failures such as decarburization, while 0Cr18Ni10Ti suffers from sensitization-intergranular corrosion failure at temperatures between 425–815°C. Occasional temperature spikes, even if they last for a very short time, have little impact on the material. However, if such spikes occur frequently and for extended periods, it can lead to the complete failure of the material, potentially resulting in hazardous accidents.
The temperature reaches up to 1000°C, which is higher than the normalizing temperature of 15CrMoR. Assume that the device has experienced such a temperature spike incident but has still remained intact; now the question is whether to continue using this device. Since it is a short-term overtemperature, it should have little to do with the high-temperature endurance strength. When the temperature exceeds the normalizing temperature of the material, it inevitably alters the mechanical properties of the material. After normalizing, 15CrMoR steel plates also require tempering treatment. The temperature distribution when the equipment exceeds its operating temperature is unknown; as a result, the mechanical properties of the shell material are uneven, making it difficult to conduct verification and inspection. Furthermore, uneven heating and cooling can also cause localized residual stresses. Therefore, if the equipment reaches such a high temperature of 1000℃ over a large area, it should no longer be used, unless the entire equipment can be subjected to normalizing and tempering treatment.
However, when a flying temperature incident occurs, is it the medium temperature that reaches 1000°C, or is it the shell wall temperature? If the flying temperature lasts only for a short time, and the temperature of the medium reaches 1000°C, the temperature of the metal walls of the casing is much lower than 1000°C; heat transfer therefore requires some time. If it is determined that the wall temperature of the casing has not exceeded the tempering temperature of 15CrMoR (around 700°C), then there should be no major problem.
There shouldn’t be a temperature difference of 300 degrees between the housing and the medium either, right? ?
It is possible; it needs to be determined through heat transfer calculations. Assuming the shell has neither external insulation nor internal thermal lining, with the medium at 1000°C and the ambient atmosphere at 20°C, and following a simple linear distribution, the wall temperature of the shell is approximately 500°C. Furthermore, the heating rate during post-weld heat treatment in the furnace is generally controlled at 55°C/h (see GB150.4, clause 8.2.7.1), while it is slower outside the furnace. It takes time for the housing to heat up.