Metal forming is a common process in industry, but many people are not very familiar with it. Today, metal forming equipment manufacturers will briefly talk about the principles of metal forming.
1. The phenomenon of metal from liquid to solid state: crystallization, transfer of solutes, solidification, crystal growth, gas precipitation, formation of pores, and changes in the volume of slag metal formed by non-metallic impurities.
2. Casting solidification method: layer by layer solidification method (as the temperature decreases, the solid layer continuously thickens and gradually reaches the center of the casting), volume solidification method (during a certain period of casting solidification, if the solidification area passes through the entire cross-section of the casting at a certain moment, there are both crystallized crystals and uncured liquids in the solidification area), Intermediate solidification method (the temperature gradient on the cross-section of the casting is relatively large, and the width of the solidification area on the cross-section of the casting is between the first two):
3. What is solute redistribution and its effects P43 solute redistribution: From nucleation to crystallization, the redistribution of solute elements will continue within the solid and liquid phases throughout the entire process. Impact: The phenomenon of macroscopic and microscopic component segregation, crystal growth morphology, microstructure distribution, porosity, cracks, shrinkage porosity, and many other aspects affect the crystallization process, which to a certain extent determines the various properties of alloy materials.
4. Methods for studying the temperature field of castings: measurement method, mathematical analysis method, numerical simulation method.
5. Two ways of undercooling: hot undercooling: the undercooling state determined solely by the actual temperature distribution of the melt. Component undercooling: undercooling caused by changes in the composition and solidification temperature of the molten material in front of the interface due to solute redistribution.
The fundamental difference between hot subcooling and component subcooling is that the former is only controlled by the heat transfer process, while the latter is constrained by both heat and mass transfer processes. During crystal growth, the thermal undercooling in front of the interface is just a special case of component undercooling at C0=0, and the two are essentially consistent. Their impact on the crystal growth process is also the same.
6. The influence and factors of filling: Filling ability: The ability of liquid metal to fill the mold cavity and obtain castings with complete shapes and clear contours.
The filling capacity of liquid metal first depends on the fluidity of the metal itself, and is also influenced by external conditions such as casting properties, pouring conditions, casting structure, etc. Liquidity: One of the casting properties, which is related to the composition, temperature, impurity content, and physical properties of the metal.