Pitting, also known as pitting, pitting and oxidation pitting, is one of the most common surface defects found in stainless steel investment castings. As a general rule, this type of defect cannot be repaired and must instead be scrapped entirely. It not only raises the cost of production, but it also has an impact on the normal production schedule and delivery schedule. As a result, one of the most important tasks of Investment Casting Services workers is to figure out how to reduce and eliminate the pitting defect in castings. In this guide, we discuss the factors that contribute to pitting in Investment Casting, as well as the methods for preventing .

What Are the Root Causes of Pitting Defects in , and How Do You Correct Them?
Pitting defects are frequently found in local thick sections, corners, and inner holes of castings, and in some cases, on the entire surface of the castings they are found in.

Causes and Consequences
As shown in the preceding analysis, pitting is primarily caused by the chemical reaction between the metal oxide and the oxide in the shell material, particularly when the shell surface refractory is not properly selected, when the incoming shell surface refractory does not meet the quality requirements, or when the shell surface refractory is not properly managed after entering the factory. The surface of batch castings can be more easily pitted after they have been poured, making it easier to produce different degrees of pitting defects. The following are the primary reasons:

(1) An excessive amount of oxide in the molten metal.
(2) There are an excessive number of oxides present in the shell surface material. Because zirconium sand has the advantages of good thermal conductivity, a large heat storage capacity, and high fire resistance, according to the relevant data, zirconium sand is used as the shell surface refractory in the production of stainless steel investment castings, according to the relevant data. When the zirconium sand contains impurities such as calcium and magnesium oxides, the decomposition temperature will drop to approximately 1300 degrees Celsius, and when it contains impurities such as potassium and sodium oxides, the decomposition temperature will drop to approximately 900 degrees Celsius. Zirconium sand is the only compound that exists in the binary system ZrO2 • SiO2. During the decomposition process, amorphous SiO2 precipitates, which has a high activity and can react with alloy elements in the metal at high temperatures. As a result, pitting can occur on the surface of the casting when this occurs.
(3) Investment Castings has something to do with the baking quality of the mold shell itself.

(1) Reduce and reduce oxides in molten metal in order to improve the quality of molten metal. (2) Reduce and reduce oxides in molten metal in order to prevent Investment Casting Parts pitting defects.

– To achieve complete deoxidation, first add ferromanganese, then ferrosilicon, and finally calcium silicon, then turn off the power and let it stand for 2 minutes, and then add aluminum for final deoxidation, discharge, and filling. In other words, the secondary addition method is used for final deoxidation in the manufacturing process.10% to 0.(If the corrosion of the furnace charge is severe, the amount of aluminum should be considered the upper limit; otherwise, the lower limit should be considered.)Add supplementary deoxidation to the ladle for the second time, and it is appropriate to use aluminum 0.02% 0.05% in the final mixture.

A quality inspection must be performed on all raw materials entering the factory, and only after they have been qualified can they be allowed to enter the factory and warehouse.

The purpose of baking shell is to remove volatile substances (such as residual water, salt, mold material, and so on) from the shell and to improve the quality of the shell even further during the baking process.

(4) Use a binder that is neutral or alkaline in pH.
It is possible to use a neutral or alkaline binder if you find that the effects of the first three measures are still not satisfactory. Aluminum, chromium, zirconium, and other metal salts, such as aluminum nitrate Al (OH) 2no3, basic aluminum chloride Al (OH) 2Cl, basic chromium nitrate Cr (OH) 2no3, and basic chromium nitrate Cr (OH) 2no3, are examples of neutral binders.