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Effect of Mold Characteristics on Precision Forging

Release date:2019-03-08 The author: Click:


The influence of casting on the fluidity of precision forgings is mainly manifested in the resistance and thermal conductivity of the casting. All factors that can increase the flow resistance of gold and increase the cooling rate in the casting mould decrease the flow rate. If the inner runner has small cross section, rough cavity surface and poor permeability, it will increase the flow resistance of liquid metal and reduce the flow rate, thus reducing the flow of liquid metal. The stronger the guide cap of the casting, the faster the heat dissipation of the liquid will be, the worse the fluidity will be.


Large die forgings


During solidification and cooling, the reduction of volume and size of alloys is called shrinkage. After pouring, melted gold undergoes three interrelated shrinkage stages: liquid shrinkage, solidification shrinkage and solid shrinkage to room temperature.

Liquid shrinkage refers to the volume shrinkage of metal due to the decrease of temperature in precision forging. The difference between the volume shrinkage and the initial solidification temperature is proportional, which is one of the main reasons for shrinkage and porosity.

Solidification shrinkage refers to the volume shrinkage of liquid metal in the solidification stage. The solidification of pure metal and alloy crystallized at constant temperature is caused by liquid-solid phase transformation. In addition to the shrinkage caused by liquid-solid phase transformation, the alloy with a certain range of crystallization temperature also shrinks due to temperature drop during solidification. Generally, the shrinkage of casting is mainly caused by the reduction of liquid level in the cavity caused by solidification shrinkage.

For example, there are residual shrinkage holes, bubbles, looseness and inclusions in ingot or steel, which may lead to cracking of forgings. Forging cracks caused by metallurgical reasons are often accompanied by a large number of oxide, sulfide and silicate inclusions.

The raw materials of high carbon and high alloy steels are prone to serious second phase segregation such as carbide. If they are not smashed and evenly distributed during forging, the mechanical properties of forgings will be reduced, and the forgings may be cracked or distorted during heat treatment. If scratches, scars, folds and cracks exist on the surface of raw materials, the forgings will be defective. Therefore, the raw materials must be inspected in the production of die forging factories.

Die Forging Manufacturer, Truck Front Axle, Large Die Forging Selection Linyi Hongsen Rail Transit Material Co., Ltd.


This article URL:http://en.hsforge.cn/news/413.html

Key words:Largedieforgings

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