Preparation method of solid-solution-strengthened ferritic nodular cast iron for thick and large pieces

Abstract

The invention discloses a preparation method of solid-solution-strengthened ferritic nodular cast iron for thick and large pieces. The preparation method includes the following steps that (1) pig ironand scrap steel are heated to 1460 DEG C-1520 DEG C to be melted, and the content of the C element is adjusted to 3.0%-4.0% by adding a carburant; (2) molten iron is nodulized by using a covering nodulizing method, the amount of a nodulizing agent added is 1.0%-2.0% of the weight of the original molten iron, and metal elements of Ce and Sb are added while nodulizing is carried out; (3) when a nodulizing incubation bag is prepared and the nodulizing agent is tight, a 75SiFe inoculant with the particle size of 3-8 mm uniformly covers the upper part of the nodulizing agent; (4) 0.04%-0.1% of TiCand TiN mixed nano-powder is added, and a Bi alloy with the weight being 0.004%-0.008% of the weight of the original molten iron is added; (5) metal-stream inoculation is carried out during pouring;and (6) the strengthened ferritic nodular cast iron is obtained after the molten iron is cooled. According to the preparation method of the solid-solution-strengthened ferritic nodular cast iron for the thick and large pieces, after the incubation is completed, the TiC and TiN nano-powder and the Bi element are added, so that the tensile strength and elongation of the nodular cast iron are increased; and the preparation process of the preparation method is simple, the overall weight of the thick and large pieces can be reduced, the cost is low, and industrial production is easy to implement.

Description

technical field [0001] The invention relates to the field of preparation of ferritic nodular cast iron, in particular to a preparation method of solid solution strengthened ferritic nodular cast iron for thick and large pieces. Background technique [0002] With the development of wind power generator projects around the world, as the core components of wind power projects: hubs, bases, shafts and other parts, the ferritic nodular cast iron materials used in them have higher performance requirements as the geographical conditions become harsher. . [0003] Many ferritic ductile iron parts for wind power are thick and large (wall thickness greater than 60mm). However, due to the slow cooling rate and long eutectic solidification time of thick and large ductile iron, it is easy to produce fragmented graphite during the cooling process, which will Significantly reduce the tensile strength, elongation and other properties of ductile iron. [0004] Ordinary as-cast nodular cast...

AI Technical Summary

Problems solved by technology

[0003] Many ferritic ductile iron parts for wind power are thick and large (wall thickness greater than 60mm). However, due to the slow cooling rate and long eutectic solidification time of thick and large ductile iron, it is easy to produce fragmented graphite during the cooling process, which will Significantly reduce the tensile strength, elongation and other properties of ductile iron

[0004] Ordinary as-cast nodular cast iron such as QT400-18, QT450-10, QT500-7, QT600-3, QT700-2 and other grades cannot meet the requirements of thick and large parts, while QT600-10, have better tensile strength and elongation

[0005] Invention patent CN 103710612 A discloses "a production method of as-cast ferrite-based ductile iron QT600-10", and invention patent CN104120332A discloses a "high-strength and high-toughness ductile iron 600-10 and its production process", which The tensile strength or elongation of the ductile iron produced by the technical schemes of the two patents is low, and no solution for the strength and elongation of thick and large ductile iron castings is given in the technical scheme