Austempered ductile iron and quenching technology thereof

A technology of austempering nodular iron and austempering, which is applied in the field of heat treatment of metal materials, can solve the problems of easily damaged finished products, high price, long time for nitrate melting and austempering, etc., and achieves the improvement of strength and impact resistance value and processing performance The effect of good and eliminating bad effects

Active Publication Date: 2013-09-25
高州创建铸造有限公司
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AI Technical Summary

Problems solved by technology

[0004] Moreover, in the traditional nitrate salt bath isothermal quenching process, because nitrate will not only produce a large amount of nitrite harmful substances when melting, it will seriously pollute The environment is harmful to human health, and the time for nitrate melting and austempering during the austempering process is long, resulting in low productivity and high production costs
[0005]In addition, traditional nodular cast iron is expensive due to the addition of expensive molybdenum (Mo) and nickel (Ni), which is extremely expensive. The earth has influenced the overall development of the Austempered Ductile Iron (ADI) industry
Moreover, the traditional nodular cast iron not only has weak hardenability and hardenability, but also is prone to adverse phenomena such as element microsegregation, which leads to a high rejection rate of workpieces or easy damage to finished products during use, resulting in safety failures

Method used

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  • Austempered ductile iron and quenching technology thereof
  • Austempered ductile iron and quenching technology thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0082] C 3.3 ~ 3.8%

[0083] P 0.01~0.05%

[0084] S 0.005~0.02%

[0085] Mg 0.025 ~ 0.045%

[0086] Re 0.015 ~ 0.03%

[0087] Mn 1.0 ~ 2.5%

[0088] Si 2.3 ~ 3.2%

[0089] Cu 0.3 ~ 1.0%

[0090] B 0.01 ~ 0.08%

[0091] Nb 0.05 ~ 0.2%

[0092] Cr0.1~0.3%

[0093] The rest is Fe.

[0094] Specifically, the matrix structure of the austempered ductile iron is: fine acicular ferrite with a volume percentage of 70-85%, tempered martensite with a volume percentage of 2-20%, and a volume percentage of 5-20%. 28% carbon-rich austenite.

[0095] The austempering ductile iron in this embodiment reduces the cost of austempering ductile iron by replacing the expensive molybdenum (Mo) and nickel (Ni) used in traditional ductile iron with cheap manganese (Mn) and silicon (Si) , to promote the development of the austempering ductile iron industry. At the same time, due to the addition of trace amounts of copper (Cu), boron (B), chromium (Cr), and niobium (Nb) to achieve multi-ele...

Embodiment 2

[0113] C 3.5 ~ 3.7%

[0114] P 0.01~0.03%

[0115] S 0.005~0.01%

[0116] Mg 0.03 ~ 0.04%

[0117] Re 0.015 ~ 0.025%

[0118] Mn 1.0 ~ 2.0%

[0119] Si 2.8 ~ 3.2%

[0120] Cu 0.3 ~ 0.6%

[0121] B 0.01 ~ 0.04%

[0122] Nb 0

[0123] Cr 0.1~0.15%

[0124] The rest is Fe.

[0125] Above, the matrix structure of austempered ductile iron is: fine acicular ferrite with a volume percentage content of 70%, tempered martensite with a volume percentage content of 2%, and carbon-rich austenite with a volume percentage content of 28%. body.

[0126] Simultaneously, a kind of austempering ductile iron quenching process of the present invention comprises the following steps:

[0127] (1) Heating the workpiece to the austenitizing temperature of 860~940°C, heat preservation treatment for 1.0~3.5h to saturate the austenite with carbon, and obtain carbon-rich austenite, the carbon content of which is 1.2~ 1.8%;

[0128](2) Put the workpiece treated in step (1) into graded quenchi...

Embodiment 3

[0138] C 3.3%

[0139] P 0.04%

[0140] S 0.015%

[0141] Mg 0.035%

[0142] Re 0.02%

[0143] Mn 1.5%

[0144] Si 3.0%

[0145] Cu 0.8%

[0146] B 0.02%

[0147] Nb 0.1%

[0148] Cr 0.15%

[0149] The rest is Fe.

[0150] Above, the matrix structure of austempered ductile iron is: fine acicular ferrite with 85% by volume, tempered martensite with 10% by volume, and carbon-rich austenite with 5% by volume body.

[0151] At the same time, a quenching process for austenitic ductile iron of the present invention includes the following steps: (1) Heating the workpiece to the austenitizing temperature of 890°C, and performing heat preservation treatment for 1.5 hours to saturate the austenite with carbon to obtain carbon-rich austenite Tenite, the carbon content of the carbon-rich austenite is 1.2%;

[0152] (2) Put the workpiece treated in step (1) into graded quenching oil, and cool the workpiece to above 180°C in 1 for first-stage austempering 1; wherein, the cooling...

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Abstract

The invention provides an austempered ductile iron adjusting chemical component. The chemical component uses Mn and Si as a base to substitute Mo and Ni, and contains a plurality of elements comprising Cu, B, Nb and Cr to realize low and micro alloying, so the respective effects of all elements are fully performed, the interactive effect promotion is realized, the hardenability is increased, the alloy consumption is reduced, and the cost is reduced. The invention also provides a new austempered ductile iron quenching technology matched with the austempered ductile iron. The technology is a step austempering technology using step quenching oil and an air isothermal furnace. The heat treatment of a workpiece through the technology realizes crystal grain refinement, good hardenability, high strength and toughness, low hardness (HB190-240) before the step austempering treatment, and good processing performances; and the obtained processed austempered ductile iron has a high hardness (HRC35-56) and extremely less oxidation and deformation, so the precision is guaranteed, and finishing treatments comprising grinding and the like are not needed. Compared with traditional nitrate bath austempering technologies, the austempered ductile iron quenching technology has the advantages of low cost, no generation of large amounts of harmful substances comprising nitrite or the like, low pollution and safety.

Description

technical field [0001] The invention relates to the technical field of heat treatment of metal materials, in particular to an austempering ductile iron and a quenching process thereof. Background technique [0002] Austempered ductile iron (ADI) refers to the cast iron material obtained after a certain composition of nodular cast iron is heat-treated by an austempering process. It has good comprehensive mechanical properties such as high strength, elongation and impact value, especially high bending fatigue strength and wear resistance. Therefore, austempering ductile iron (ADI) is often used to replace nodular cast iron, cast steel, forged steel, and aluminum alloys, and is widely used in transportation vehicles, diesel engines and other internal combustion engines, agricultural and forestry machinery, etc., to manufacture such as crankshafts, connecting rods, gears, Wheel hubs, spring steel plates, cylinder blocks, bushings, universal joints, and other important structura...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C37/10C21D1/22
Inventor 不公告发明人
Owner 高州创建铸造有限公司
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