Austempering heat treatment method of high bending property austempered ductile cast iron (ADI)

Abstract

The invention discloses an austempering heat treatment method of high bending property austempered ductile cast iron (ADI). The austempering heat treatment method comprises the following steps: austenitizing ductile cast iron at the temperature of 860-900 DEG C, and immediately quenching the austenitized ductile cast iron in a quenching water-based suspension medium for 1-5s, wherein the flow rate of a water-based suspension is kept to be 0.2-0.6m / s in the quenching process; then, keeping isothermality for 5-600min at the temperature of 200-300 DEG C; and finally, air cooling to room temperature. Through the heat treatment method, the ADI after heat treatment is still a mixed matrix of speculate bainitic ferrite (BF) and retained austenite (AR), the rigidity of the ADI reaches HRC 53.8, the bending strength reaches 1565.6MPa, and the deflection reaches 2.1mm.

Description

technical field [0001] The invention belongs to the technical field of heat treatment, in particular to a heat treatment method for obtaining high bending performance of Aube ductile iron. Background technique [0002] Austempered Ductile Cast Iron (ADI) is a material obtained from ductile cast iron through an austempering heat treatment process. Aube ductile iron is a new generation of ductile iron developed in the past fifty years. Due to its high comprehensive performance, good process performance, small specific gravity, high vibration absorption, and low cost, it has strong competitiveness in the machinery manufacturing industry, and is known as a high-tech material in the field of mechanical structural materials. Compared with other materials, ADI Performance advantages such as figure 1 shown. Depend on figure 1 It can be seen that the tensile strength of high-performance ADI can reach 900-1200MPa, twice that of ductile iron, reaching or even exceeding alloy steel,...

AI Technical Summary

Problems solved by technology

However, for some nodular cast irons with different compositions, during the austempering process, due to the slow cooling capacity of the salt bath, other phases besides bainitic ferrite and retained austenite will appear, reducing the hardness of the workpiece. mechanical properties

[0007] 2. High energy consumption of nitrate

Therefore, for large size parts, it is difficult to realize the austempering process

[0008] 3. Nitrate pollutes the environment and harms the human body

It is easy to deposit dross in the salt bath furnace, and it is difficult to remove these dross when they are hard

[0010] Therefore, the problem existing in the prior art is: the use of nitrate in the Aube ductile iron process has many disadvantages

And the hardness value of the heat-treated workpiece is low, so it is difficult to be really used in industrial production

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