Ferrite nodular cast iron and production method thereof

Abstract

The invention discloses a ferrite nodular cast iron and a production method thereof, and belongs to the technical filed of metal smelting. The tensile strength, the elongation percentage and the hardness of the cast iron are 600-700MPa, 15-20% and 150-210HB respectively. The production method comprises the steps of burdening, melting, inoculating and carrying out solid solution reinforcement. The ferrite nodular cast iron has the advantages of high elongation percentage, high strength and low surface hardness, and solves a technical problem that the strength, the elongation percentage and the surface hardness cannot be simultaneously considered.

Description

technical field [0001] The invention relates to a nodular cast iron and a production method thereof, in particular to a ferritic nodular cast iron and a production method thereof, belonging to the technical field of metal smelting. Background technique [0002] Ductile cast iron is treated with spheroidization and inoculation, and the graphite form is spherical cast iron, which effectively improves the mechanical properties of cast iron, especially the plasticity and toughness, so as to obtain higher strength than carbon steel. According to different shapes, nodular cast iron Included in: 1. Ferrite has a body-centered cubic lattice, which is an interstitial solid solution of carbon dissolved in α-Fe, which is called ferrite, that is, α-Fe and its based solid solution, represented by the symbol F; 2. Pearlite is a eutectoid of ferrite and cementite formed by eutectoid transformation of austenite. Its form is a layered complex phase in which ferrite thin layers and cementite...

AI Technical Summary

Problems solved by technology

There are different forms of cementite in iron-carbon alloys, and their quantity, shape and distribution have a direct impact on the properties of iron-carbon alloys. When the current ductile iron is stably solidified according to the phase diagram of the Fe-C-Si ternary alloy system, About 2-3% w(Si) promotes the precipitation of graphite. The metallographic structure of ductile iron has two basic types: ferrite and pearlite. At the same time, the mechanical properties of ductile iron are as follows: As for the low strength and high elongation of the material; the tensile strength is 180-280MPa; the elongation is 30--50%; the hardness is 50-80HB; 2. The intermediate state of ferrite and pearlite, so that it has suitable strength and elongation ;3. Full pearlite so that high strength and low elongation, the performance of pearlite is: tensile strength 770MPa; hardness above 210HB, elongation = 20%~35%, and the current technology needs to obtain about 700Mpa The mechanical strength of metallography requires a higher proportion of pearlite content or even full pearlite, but at the same time the elongation rate is greatly reduced, and the hardness is increased, which brings difficulties and cost increases to subsequent machining. The ferrite metallographic structure has significantly improved elongation and reduced hardness, which is convenient for machining, but the strength is low, generally ≤450Mpa, which cannot meet the corresponding needs. In production and application practice, a matrix structure with ferrite is required, namely It has high elongation and low surface hardness, and has good mechanical properties of ductile iron to meet the needs of corresponding engineering and processing