Today, let's take a look at the crane wheel forgings if it has a burnt condition, what harm it has, and its preventive measures.
When the steel material is heated to near the melting point, not only the austenite grains are coarse, but also the oxidizing gas in the furnace gas penetrates into the boundary of the grains, causing the intergranular substances Fe, C, and S to oxidize to form a fusible eutectic. The relationship between the grains is destroyed, and this phenomenon is called overburning. The temperature at which the overheating occurs is called the firing temperature, which depends on the chemical composition of the steel.
Overburning is a fatal heating defect. The over-fired steel material greatly reduces the strength of the crane wheel forgings, loses the plasticity, can not be forged, breaks into pieces with one hit, and the fracture grains are coarse and grayish blue. The burnt steel is irreparable. Waste products, only re-smelting back to the furnace When manufacturing non-essential parts, the partially over-fired steel material can be partially burned off, the rest can be used, or the other parts can be downgraded and modified.
Preventive measures for over-burning: Correctly formulate heating specifications, strictly control the heating temperature of crane wheel forgings and the holding time under high temperature; control the gas composition in the furnace, reduce the excess air volume, and cause weak oxidizing furnace gas; ensure temperature measurement and control The temperature meter is reliable and accurate, the operator should diligently adjust, diligently watch and record carefully; when heating in the flame furnace, the billet and the blasting port should be kept at a certain distance, and the flame is strictly prohibited from directly contacting the billet. When the resistance furnace is heated, the distance between the blank and the resistance wire should be controlled to avoid local over-burning; in the high-carbon steel and low-carbon alloy steel which are more easily burned, special attention should be paid to prevent over-burning; Over-burned steel materials should be resolutely removed to prevent mixing into the finished product, resulting in greater losses.
In summary, these are the hazards that can occur if the crane wheel forgings are over-burned during the forging process. Everyone should pay special attention during the production process. There is also its prevention measures, everyone should also keep in mind.