Study On Low Temperature Properties And Wear Properties Of ADI Materials

Austempered ductile iron(ADI) is a good comprehensive mechanical properties of materials.Both at home and abroad,Study on low temperature mechanical properties of ADI which has high strength and high toughness are less.In order to study the law of the two kinds of ADIs(ADI-1 and ADI-2) mechanical properties at low temperatures,the low temperature impact tests,tensile tests,hardness tests and wear tests have been made in this experiment.Setting the test temperature range is 20 ℃,-20 ℃,-40 ℃,-60 ℃.At the same time,the analysis of metallographic analysis,the fracture analysis of SEM and XRD analysis also have been made.And the finally conclusion draws the following:(1)With the decrease of temperature,the tensile strength of two kinds of ADI materials increased significantly,but the plasticity and toughness have dropped dramatically and the temperature the fracture mechanisms of two kinds of ADI materials have changed from ductile fracture to mixed fracture to brittle fracture changes.(2)Compared with normal temperature,at-20 ℃,the tensile strength of ADI-1 increased by 9.69%,the elongation decreased 25.62%,the impact toughness decreased by 51.85%.At-40 ℃,the tensile strength increased by 14.48%,the elongation decreased 32.34%,the impact toughness decreased by 63.03%,but it also reached 43 J which shows that at-40 ℃the impact toughness of ADI-1 is well.At-60 ℃,the tensile strength is increased by 19.80%,the impact toughness decreased by 34.62%,but the elongation and impact toughness decreased more than 70%,the hardness increased but not obvious.In summary,the mechanical properties of ADI-1 material under the low temperature are relatively good.(3)At-20 ℃,relative to the normal temperature condition,the tensile strength of ADI-2 increased by 5.22%,the elongation decreased by 12.65%,the impact toughness is 75 J which decreased by 19.36%.At-40 ℃,the tensile strength increased by 6.84%,the elongation decreased by 20.17%,the impact energy decreased by 52.69%.At-60 ℃,the tensile strength of ADI-2 improved 8.00%,the elongation decreased 27.8 %,impact energy 31 J,decreased by 66.67%,temperature change has little effect on the hardness of ADI-2.In summary,the mechanical properties of ADI-2 at low temperature is more stable than ADI-1.(4)The content of austenite with the change of temperature was detected by XRD.Verify that residual austenite in the ADI materials,under the effect of low temperature,will be changed to martensite and the ratio in the ADI-1 material are more than that in the ADI-2.(5)At room temperature the wear properties of ADI-1 is well,the material after-20 ℃treatment,the wear properties of ADI-1definitely improved,but with the temperature decreases,the wear properties of the ADI-1 does not change significantly,it shows that the appropriate low temperature treatment can improve the wear properties of the ADI-1 material and low temperature treatment can also be appropriate to broaden the scope of material ADI-1.But low temperature heat treatment on wear properties of ADI-2 has little effect.(6)ADI wear mechanism of pin on disc type wear test conditions mainly for oxidation wear,abrasive wear and flaking wear.