Research On Microstructure And Properties Of Adi Pipes For Concrete Pump Truck

Concrete pump trunk pipes worked in very bad condition.They bear not only the pressure of the concrete,but also the severe wear of gravel and sand and erosion of the cement paste.In practical application,wear out and tube burst were the main failure forms,and the tube burst was the most harmful.In this paper,combined with the characteristics of Austempered Ductile Iron material(high impact toughness,good abrasion resistance and fatigue resistance),we tried to apply ADI material to concrete pump truck pipe today.For the ADI material for concrete pump truck pipe,this paper has mainly researched the failure mode of concrete pump truck bent pipe;the impact of isothermal quenching temperature,silicon content and copper content against the structure and performance of ADI concrete pump truck bent pipe,and the structure and performance of centrifugal casting ADI pipe after heat treatment.In the test,the metallographic microscope and scanning electron microscope were used to observe the microstructure.The hardness and impact toughness were tested by using Brinell hardness tester,Rockwell hardness tester and impact tester.And the MLS-225 wet sand-rubber wheel abrasion tester and MLD-10 dynamic load abrasive wear tester were used to detect the wear resistance and the corrosion resistance.The research shows that: 1)In all part pipes of concrete pump trunk,the wear of the last bend pipe was the most serious.Abrasion was the main cause of the concrete pump trunk bend pipes failure,combined with certain impact of erosion.Abrasive wear and corrosive wear were the main abrasion form;2)In the range of the isothermal temperature of 240? to 320?,with the increase of isothermal temperature,the hardness of ADI bent pipe decreased,but impact toughness improved,the residual austenite content increased,the residual austenite carbon content increased;3)In the range of the isothermal temperature of 240 ? to 320?,the corrosion resistance of ADI increased first and then decreased,and achieved the best performance at 280?.And the weight loss of wet sand-rubber wheel wear was minimum at 280? for sample composition in 2.4% silicon,0%copper and 2.4% silicon,0.6% copper.The corrosive wear performance achieved the best at 260? and 300? respectively;4)Within the scope of the silicon content of 1.9% to 2.9%,with the increasing of silicon content,the residual austenite content and the residual austenite carbon content increased first and then decreased.When the silicon content reached 2.65%,the residual austenite content and the residual austenite carbon content were in maximum;5)Within the scope of the silicon content of 1.9% to 2.9%,the erosion resistance of ADI was enhanced with the increasing of silicon content.When the silicon content reached 2.1% and 2.4%,the weight loss of wet sand rubble wheel wear and the corrosive wear reached maximum respectively.6)Within the scope of the copper content of 0% to 1.1%,the hardness value had little change,and the impact toughness firstly lowered and then improved.When the copper content reached 0.6%,the weight loss of wet sand rubber wheel wear reached minimum,and the corrosive wear value almost the same.7)For the centrifugal casting ADI pipe,the smaller the diameter and wall thickness of pipe were,the more the number of graphite ball had.In the range of the isothermal temperature of 300? to 380?,erosion wear performance was better and corrosion resistance was worse under the condition of ADI sample whose graphite ball was more.Under the isothermal temperature of 360?,the weight loss was minimum.