NEWS

There are many two reasons for harming the quality of stainless steel forgings, each of which is the raw material and the casting process.

Harm of 1. Raw Materials to the Quality of Stainless Steel Forgings

The good quality of raw materials is a prerequisite for ensuring the quality of forgings. If there are shortcomings in raw materials, it may affect the forming process of forgings and the quality of forgings. If the chemical molecules of the raw materials exceed the required range or the content of residue elements is too high, it will cause relatively great harm to the forming and quality of forgings. For example, S, B, Cu, Sn and other classics are easy to produce low melting point phases, making stainless steel forgings prone to thermal brittleness. In order to obtain a substantially fine crystal steel, the residual aluminum content in the steel needs to be manipulated within a certain range. The aluminum content is too small to manipulate the crystal, which is easier to make the actual grain size of forgings not close. With too much aluminum content, it is easy to produce wood grain-like fracture surface and tear mark-like fracture surface under the condition of producing fibrous structure by pressure processing.

Harm of the Whole Process of 2. Casting Process to the Quality of Stainless Steel Forgings

The whole process of casting process is generally composed of the following process, that is, opening, heating, molding, refrigeration after forging, pickling passivation and post-forging heat treatment process. If the processing technology is unreasonable in the forging process, a series of shortcomings of stainless steel forgings may be produced. If the heating process includes the furnace environment temperature, heating environment temperature, heating rate, heat insulation duration, furnace gas composition and other links, if the heating is unreasonable, such as the heating environment temperature is too high and the heating time is too long, it will also cause carburizing, over-temperature, coarse crystal and other shortcomings. For large cross-sectional size and poor heat transfer, low plasticity of the embryo, if the heating faster and faster, the insulation time is too short, usually make the temperature distribution uneven, resulting in internal stress, so that the embryo cracking.

Forging molding technology includes deformation method, deformation degree, deformation environment temperature, deformation rate, stress state, mold condition and wetting requirements, etc. If the molding process is unreasonable, it may cause thick crystals, uneven crystals, various cracks, disassembly, flow, vortex, as-cast tissue residues, etc. In the refrigeration link after forging, if the processing technology is unreasonable, it may cause refrigeration cracks, small white spots, network carbide, etc.