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01
2022
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11
The foundry would like to share some relevant precautions for cooling operations in the precision casting process.
Let the foundry talk to you about some related precautions for cooling operations in the precision casting process. You can take a look at the following content. We hope that the content introduced by our foundry can give you a more detailed understanding of casting.
Foundry Let's talk about Cooling operations in precision casting Some related precautions, you can take a look at the following content. Hope we Foundry The content introduced can make everyone Casting Have a more detailed understanding.
The foundry understands that fine castings are being used more and more widely, and there are more and more processing technologies. Among them, the cooling process is an essential process, and some have to go through the solid phase transformation of the alloy. When a phase change occurs, the metal undergoes relative changes, such as the volume of carbon steel decreasing when the phase changes to the phase, and the volume increasing when the phase changes to the eutectoid phase.
However, if the temperature of each part of the casting is the same, micro-stress may not be generated during the solid phase transformation, but only micro-stress. When the phase transformation temperature is higher than the critical temperature of elastic-plastic transformation, the alloy is in a plastic state during the phase transformation process. Even if there is temperature in all parts of the casting, the phase transformation stress is not large and will gradually decrease or even disappear.
The foundry said that if the phase transformation temperature of the casting is lower than the critical temperature, and the temperature difference between the parts of the casting is large, and the phase transformation time of each part is different, it will cause microscopic phase transformation stress, because the phase transformation time is different, the phase transformation stress may become temporary stress or residual stress.
When the thin-walled part of the casting undergoes a solid phase transformation, the thick-walled part is still in a plastic state. If the specific volume of the new phase is greater than that of the old phase during the phase transformation process, the thin-walled part expands during the phase transformation process, while the thick-walled part is plastically stretched. As a result, only a small tensile stress is generated in the casting, which gradually disappears as time goes by. In this case, if the casting is kept cooling, the thick-walled part will undergo a phase change and increase its volume. Because it is already in an elastic state, the thin-walled part will be elastically stretched by the inner layer, resulting in tensile stress. The thick-walled part is elastically contracted by the outer layer, forming compressive stress. In this case, the residual phase transformation stress and the residual thermal stress have opposite signs and can cancel each other out.
The foundry said that when the thin-walled part of the casting is released into the solid phase transformation, the thick-walled part is already in an elastic state. If the new specific volume is greater than the old phase, the thick-walled part is elastically stretched to form tensile stress, and the thin-walled part is elastically contracted to form temporary compressive stress. At this time, the sign of the phase transformation stress is the same as the sign of the thermal stress, that is, the stress is superimposed. When the casting is continuously cooled until the thick-walled part undergoes a phase change, the specific volume becomes larger and expands, causing the phase transformation stress formed in the previous stage to disappear.
I believe that through the above introduction, everyone has a lot of understanding of the foundry. If you want to know more about this, you can contact us. We can introduce it to you from different aspects. Our foundry has many years of experience in this industry.
Foundry
Shandong Gongchen Machinery Technology Co., Ltd.
Contact QQ: 258506508
Mobile Number:15621618888
Phone:0536-7691368 7691229
Fax: 0536-7691229
Contact Email:guisongzhng8@gmail.com
Website:www.shandonggongchen.com Gongchen.China Valve Castings.China
Address: Mucun Town, Fangzi District, Weifang City, Shandong Province
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