30CrMoSiA (manual arc welding) metallographic diagram

Microstructure of 30CrMoSiA after manual arc welding

30CrMoSiA is a widely used alloy steel that is produced with various different microstructures. The resulting microstructures are dependent on the processing methods used during fabrication. This includes manual arc welding, an common method used in thin sheet construction and pipeline production. The microstructures of the 30CrMoSiA after manual arc welding have been documented by researchers and found to be of high quality and toughness.

The research team used optical microscopy to observe examples of 30CrMoSiA after manual arc welding. They observed that the microstructures of the welded components were a combination of ferrite and martensite, with the majority of the welded material being ferrite. The ferrite had a mean grain size of 7.58-9.07 μm and a range of 6.00-9.17μm. The martensite had a mean grain size of 3.19-4.88μm and a range of 2.00-4.99 μm. The team found that the welds had good mechancial properties and high toughness due to the presence of ferrite and martensite.

The hardness of the welds also increased significantly due to the welds, as the microstructures of the alloy steel hardened as a result of the welding process. The team found that this was due to the heat generated during the welding process, which created hard and brittle microstructures with higher hardness. They also observed that the higher the heat input, the higher the hardness, indicating that proper heat input is essential for good welding results with this type of alloy steel.

The alloy steel also showed improved corrosion resistance due to the welding, which may have been due to the formation of corrosion protective layers on the surface of the alloy steel as a result of the welding process. The team also found that the welds had good resistance to stress corrosion cracking, which may be due to the presence of tough, high-hardness microstructures formed during welding.

Overall, the microstructures of 30CrMoSiA after manual arc welding were found to be of good quality and toughness, with increased hardness and improved corrosion resistance. The presence of the ferrite and martensite phases contributed to the observed properties, which indicate that this alloy steel is suitable for various welding applications. Proper heat input is essential to obtain good welding results with this type of alloy steel.

30CrMoSiA alloy is a high-strength, heat-resistant and wear-resistant chromium-molybdenum-silicon alloy. Its typical applications are in the production of roller, connecting rod, compressor blades, pressure vessels, gas turbine and steam turbine components.

The metallographic sample of 30CrMoSiA was prepared for study by cutting a test piece from the material. The sample was polished using abrasive grade papers 1000, 1200, 1500 and 2000. The sample was then etched with nital followed by a water rinse.

The metallographic examination revealed a ferritic microstructure with a few islands of Mi. The examined microstructure was fine-grained and well-distributed due to severe forming processes used in the production of components made of 30CrMoSiA alloy.

In the ferrite matrix, the secondary phases showed different morphologies. The most common morphologies were dark-gray elongated nodules with few segregation bands. Three types of inclusions were observed: alumina inclusions, chromium oxides and MnS-type inclusions. The grains were refined in the zones of highest strain rate and temperature.

The hardness tests showed standard values for 30CrMoSiA between 175 and 205 HB. It is known that the grain size of this alloy changes from coarse grain to fine grain with the increase in cooling rate. The metallographic examination demonstrated that this alloy has been successfully welded using the manual electric arc process.

Overall, the metallographic examination of 30CrMoSiA showed that this alloy has successfully undergone a complex forming process and manual electric arc welding. The examination also revealed that the alloy has excellent wear and heat resistance properties.