Papers by Keyword: Metallurgical Quality

Abstract: A steel plate with thickness（3~12）mm named 30CrMo（%：0.29~0.34C、0.17~0.37Si、0.40~0.70Mn、≤0.015P、≤0.010S、≤0.30Mo、0.80~1.10Cr）was developed by converter melting and hot continuous rolling. Good metallurgical quality, mechanical properties and strip shape are ensured by accurately control of smelting, rolling, coiling and decoiling process. The results show that 30CrMo steel has high purity, uniform structure and stable properties, perfect plate shape, and meets requirements of consumer.

Abstract: The important factors that affect the formability of the cold forging steel are its surface quality and internal defects. The cracking phenomenon was taken place during cold forging of ML25Mn steel. In this study, microstructural analyses were made on around the cracked regions of the steel. The reason of cracking, which occurred during cold forging for ML25Mn steel, was investigated based on SEM observation in detail. The results have shown that the crack forming during cold forging process is not related to the chemical composition for ML25Mn steel. Cracking is not resulted from high hardness of the steel rods. There are some non-metallic inclusions in the matrix of ML25Mn steel, and the film-like inclusions are composed of MnS, CaS and complex oxides containing Mg, Al, Mn, Fe, S, Ca and O. The formation of non-metallic inclusions is the result of the deoxidation and the solidification during smelting and casting of steel.

Abstract: Cold forging has various advantages compared to other forming processing. Cracking phenomenon was taken place during cold forging of ML25Mn steel. In this study, microstructural analyses were made on the cracked regions of the steel. The reason of cracking phenomenon occurring during cold forging for ML25Mn steel was investigated based on SEM observation in detail. The results have shown that ML25Mn steel presents lower strength and toughness. A larger amount of inclusions which are composed of MnS and complex oxides containing Mg, Al, Mn, Fe, S, Ca and O are found, and the complex inclusion might be brought during the deoxidation and the solidification in smelting and casting. Non-metallic inclusions result in significant stress concentration, which cause cracking phenomenon occurring during cold forging of ML25Mn steel.

Abstract: The Al sheet used for pressure can manufacture (or called Al piece) was prepared by different melt-treatment techniques and using the lower grade commercial purity raw Al (Al99.5). And the influence laws of melt-treatment techniques on the metallurgical quality and mechanical properties of Al piece were investigated. It is found that high-efficient melt-treatment technique improves the metallurgical quality of Al piece remarkably, that is, the rate of removing inclusions and the extent of lowering porosity amount to about 66.6% and 87.0%, respectively, and as-cast mean grain diameter decrease to a great extent, and the coarse and long needle/flake Fe-rich impurity phases transform into complex compounds of tiny, sphere/short stick form, which makes fracture mechanism of the material be transformed into the congregation of transgranular micro-hole, thus raising mechanical properties of this material remarkably. Its metallurgical quality and mechanical properties have reached or exceeded the level of present products. It is feasible that Al piece is made by using the lower grade commercial purity raw Al. The viewpoint that the purification is the fundamental and key process, i.e., the basic of modification and grain refinement processes, has been also further tested and verified.