What is the spinning process of Jianzhi Mashan Iron and Steel Co., Ltd.'s malleable steel pipe fittings?

The welding temperature of malleable steel pipe fittings in Jianzhi Maanshan Iron and Steel Co., Ltd. is mainly affected by the high-frequency eddy current thermal power, which is mainly affected by the current frequency. The eddy current thermal power is proportional to the square of the current excitation frequency; and the current excitation frequency is affected by the excitation voltage, The effect of current and capacitance and inductance.

The excitation frequency is inversely proportional to the square root of the capacitance and inductance in the excitation circuit, or proportional to the square root of the voltage and current. As long as the capacitance, inductance or voltage and current in the circuit are changed, the excitation frequency can be changed, so as to control the welding temperature. Purpose. For low carbon steel, the welding temperature is controlled at 1250~1460°C, which can meet the penetration requirements of the pipe wall thickness of 3~5mm. In addition, the welding temperature can also be achieved by adjusting the welding speed.

When the input heat is insufficient, the edge of the heated weld cannot reach the welding temperature, and the metal structure remains solid, forming incomplete fusion or incomplete penetration; when the input heat is insufficient, the heated edge of the weld exceeds the welding temperature, resulting in Overburning or dripping causes the weld to form a molten hole.

In the production of malleable steel pipe fittings of Jianzhi Maanshan Iron and Steel Company, besides iron (Fe), five elements are important: carbon (C), silicon (Si), manganese (Mn), sulfur (S), and phosphorus (P).

1. Carbon (C), is a strong graphitization-promoting element. The process of carbon polymerization to produce graphite is similar to how we stack boxes. First they tend to pile up and expand around graphite that has formed groups. So, a core is very important.

2. Silicon (Si) is also a strong graphitization-promoting element. With the gradual increase of silicon content, the amount of graphite in the product is also rising sharply, so in the production process of malleable iron pipe fittings, that is, malleable steel pipe fittings, the silicon content in the product should be controlled between 1.2-1.8%.

3. Manganese (Mn) and sulfur (S), both of which are harmful elements that hinder the graphitization process. In the production process of malleable cast iron, sulfur will seriously hinder the graphitization process and greatly prolong the annealing time. Therefore, in cast iron production, the sulfur content should be as low as possible.

The manganese content in malleable cast iron should be controlled between 0.8% and 1.2%.

4. Phosphorus (P), phosphorus has little effect on the graphitization process of malleable steel, but if the phosphorus content is too high, it will reduce the toughness of the casting. Causes the product to be brittle and brittle.

5. For other elements, in the production of malleable steel pipe fittings, the above five elements are the main influencing elements, and other trace elements generally have little influence. However, if the content of certain elements is too high due to raw material problems, it will also have some negative effects on the material properties of the product.