To investigate the effect of grain refinement on the material properties of recently developed Al-25 Zn-3 Cu based alloys,Al-25 Zn-3 Cu,Al-25 Zn-3 Cu-0.01 Ti,Al-25 Zn-3 Cu-3 Si and Al-25 Zn-3 Cu-3 Si-0.01 Ti alloys we...To investigate the effect of grain refinement on the material properties of recently developed Al-25 Zn-3 Cu based alloys,Al-25 Zn-3 Cu,Al-25 Zn-3 Cu-0.01 Ti,Al-25 Zn-3 Cu-3 Si and Al-25 Zn-3 Cu-3 Si-0.01 Ti alloys were produced by permanent mold casting method.Microstructures of the alloys were examined by SEM.Hardness and mechanical properties of the alloys were determined by Brinell method and tensile tests,respectively.Tribological characteristics of the alloys were investigated by a ball-on-disc type test machine.Corrosion properties of the alloys were examined by an electrochemical corrosion experimental setup.It was observed that microstructure of the ternary A1-25 Zn-3 Cu alloy consisted ofα,α+ηandθ(Al2Cu)phases.It was also observed that the addition of 3 wt.%Si to A1-25Zn-3Cu alloy resulted in the formation of silicon particles in its microstructure.The addition of 0.01 wt.%Ti to the Al-25Zn-3Cu and Al-25 Zn-3 Cu-3 Si alloys caused a decrement in grain size by approximately 20%and 39%and an increment in hardness from HRB 130 to 137 and from HRB 141 to 156,respectively.Yield strengths of these alloys increased from 278 to 297 MPa and from 320 to 336 MPa while their tensile strengths increased from 317 to 340 MPa and from 334 to 352 MPa.Wear resistance of the alloys increased,but corrosion resistance decreased with titanium addition.展开更多
The aim of the present study was to investigate the influence of Mg addition and T6 heat treatment on microstructure,mechanical and tribological properties of the Al-Si-Cu-Mg alloys.In this context,a series of Al-12Si...The aim of the present study was to investigate the influence of Mg addition and T6 heat treatment on microstructure,mechanical and tribological properties of the Al-Si-Cu-Mg alloys.In this context,a series of Al-12Si-3Cu-(0.5-2.5)Mg(wt.%)alloys were produced by permanent mould casting,and then subjected to T6 treatment.Their microstructure and mechanical properties were investigated using OM,XRD,SEM,EDS along with hardness,tension,compression and Charpy impact tests.Dry sliding friction and wear properties of the alloys were studied using a ball-on-disk type tester.It was observed that the microstructure of as-cast Al-12Si-3 Cu-Mg alloys consisted of a(Al),Si,O-CuAb,0-Mg_(2)Si,0-AbMg_(8)Cu(2)Si_(6) and π-AhMg_(3)FeSi_(6) phases.T6 heat treatment gave rise to nearly spherodization of eutectic Si particles,formation of finer 0-CuAH and 0-Mg_(2)Si precipitates and elimination of Chinese script morphology of 0-Mg_(2)Si phase.The addition of Mg up to 2.5 wt.%decreased the hardness,tensile and compressive strengths,tensile elongation and impact toughness of the as-cast and T6-treated alloys and increased their friction coefficient and volume loss.T6 treatment,on the other hand,led to a significant increase in mechanical properties and wear resistance of as-cast alloys.展开更多
Reliability and wear resistance of cutting picks play a significant role in coal mine exploitation with coal shearers.Tool bit separation,blade breaking,severe erosion of the cutting body and fatigue fractures are the...Reliability and wear resistance of cutting picks play a significant role in coal mine exploitation with coal shearers.Tool bit separation,blade breaking,severe erosion of the cutting body and fatigue fractures are the main reasons for failure of cutting picks.We carried out carburization on a 30CrMnMo alloy to synthesize a new cutting pick material with improved mechanical properties and high wear resistance.The results indicated that carburization can effectively strengthen the surface of the 30CrMnMo alloy by forming a thick carburized layer and thus significantly improve the surface hardness and wear resistance.In addition,the excellent toughness of 30CrMnMo alloy as a substrate of cutting picks can prevent brittle ruptures and fatigue fractures under high impact stress conditions.The significant decrease in both frictional coefficient and rate of erosion of this carburized 30CrMnMo alloy suggests that this alloy is a potential material for cutting picks of coal shearers after rational carburization.展开更多
To prolong the life-span of crush hammers in the pyrite concentrate workplace of Ganbazi Coal Preparation Plant of Chongqing Nantong Mining Ltd., we used a progressive damage constitutive model based on the ductile an...To prolong the life-span of crush hammers in the pyrite concentrate workplace of Ganbazi Coal Preparation Plant of Chongqing Nantong Mining Ltd., we used a progressive damage constitutive model based on the ductile and shear damage fracture energy to analyze the hammer wear failure caused by the impact and abrasion on the hammer surface by pyrite, and carried out simulation analysis with the explicit algurithm on hammer leftovers from the plant during the process of coarser pyrite comminution. The simulation results are consistent with hammer wear failure caused by pyrite impact. Then we proposed corrective measures to prolong hammer life-span. Results of the production test in the Ganbazi Coal Preparation Plant showed that non-clearance hammers can avoid wear erosion, and adding steel bonded tungsten carbides F3002 prolonged the hammer life- span. The effect of austenitic manganese steel work-hardening was not prominent. Therefore, the hammer failure was mainly caused by superficial abrasion instead of fatigue cracks appearing when grains acted on the hardening layer.展开更多
文摘To investigate the effect of grain refinement on the material properties of recently developed Al-25 Zn-3 Cu based alloys,Al-25 Zn-3 Cu,Al-25 Zn-3 Cu-0.01 Ti,Al-25 Zn-3 Cu-3 Si and Al-25 Zn-3 Cu-3 Si-0.01 Ti alloys were produced by permanent mold casting method.Microstructures of the alloys were examined by SEM.Hardness and mechanical properties of the alloys were determined by Brinell method and tensile tests,respectively.Tribological characteristics of the alloys were investigated by a ball-on-disc type test machine.Corrosion properties of the alloys were examined by an electrochemical corrosion experimental setup.It was observed that microstructure of the ternary A1-25 Zn-3 Cu alloy consisted ofα,α+ηandθ(Al2Cu)phases.It was also observed that the addition of 3 wt.%Si to A1-25Zn-3Cu alloy resulted in the formation of silicon particles in its microstructure.The addition of 0.01 wt.%Ti to the Al-25Zn-3Cu and Al-25 Zn-3 Cu-3 Si alloys caused a decrement in grain size by approximately 20%and 39%and an increment in hardness from HRB 130 to 137 and from HRB 141 to 156,respectively.Yield strengths of these alloys increased from 278 to 297 MPa and from 320 to 336 MPa while their tensile strengths increased from 317 to 340 MPa and from 334 to 352 MPa.Wear resistance of the alloys increased,but corrosion resistance decreased with titanium addition.
文摘The aim of the present study was to investigate the influence of Mg addition and T6 heat treatment on microstructure,mechanical and tribological properties of the Al-Si-Cu-Mg alloys.In this context,a series of Al-12Si-3Cu-(0.5-2.5)Mg(wt.%)alloys were produced by permanent mould casting,and then subjected to T6 treatment.Their microstructure and mechanical properties were investigated using OM,XRD,SEM,EDS along with hardness,tension,compression and Charpy impact tests.Dry sliding friction and wear properties of the alloys were studied using a ball-on-disk type tester.It was observed that the microstructure of as-cast Al-12Si-3 Cu-Mg alloys consisted of a(Al),Si,O-CuAb,0-Mg_(2)Si,0-AbMg_(8)Cu(2)Si_(6) and π-AhMg_(3)FeSi_(6) phases.T6 heat treatment gave rise to nearly spherodization of eutectic Si particles,formation of finer 0-CuAH and 0-Mg_(2)Si precipitates and elimination of Chinese script morphology of 0-Mg_(2)Si phase.The addition of Mg up to 2.5 wt.%decreased the hardness,tensile and compressive strengths,tensile elongation and impact toughness of the as-cast and T6-treated alloys and increased their friction coefficient and volume loss.T6 treatment,on the other hand,led to a significant increase in mechanical properties and wear resistance of as-cast alloys.
基金the Youth Foundation of China University of Mining & Technology (No.2009A056)the Tribology Science Fund from State Key Laboratory of Tribology at Tsinghua University (No.SKLTKF08A01)+1 种基金the National Natural Science Foundation of China (Nos.50905180 and 51005234)the National Science and Technology Pillar Program in the Eleventh Five-Year Plan Period (No.2008BAB36B02)
文摘Reliability and wear resistance of cutting picks play a significant role in coal mine exploitation with coal shearers.Tool bit separation,blade breaking,severe erosion of the cutting body and fatigue fractures are the main reasons for failure of cutting picks.We carried out carburization on a 30CrMnMo alloy to synthesize a new cutting pick material with improved mechanical properties and high wear resistance.The results indicated that carburization can effectively strengthen the surface of the 30CrMnMo alloy by forming a thick carburized layer and thus significantly improve the surface hardness and wear resistance.In addition,the excellent toughness of 30CrMnMo alloy as a substrate of cutting picks can prevent brittle ruptures and fatigue fractures under high impact stress conditions.The significant decrease in both frictional coefficient and rate of erosion of this carburized 30CrMnMo alloy suggests that this alloy is a potential material for cutting picks of coal shearers after rational carburization.
文摘To prolong the life-span of crush hammers in the pyrite concentrate workplace of Ganbazi Coal Preparation Plant of Chongqing Nantong Mining Ltd., we used a progressive damage constitutive model based on the ductile and shear damage fracture energy to analyze the hammer wear failure caused by the impact and abrasion on the hammer surface by pyrite, and carried out simulation analysis with the explicit algurithm on hammer leftovers from the plant during the process of coarser pyrite comminution. The simulation results are consistent with hammer wear failure caused by pyrite impact. Then we proposed corrective measures to prolong hammer life-span. Results of the production test in the Ganbazi Coal Preparation Plant showed that non-clearance hammers can avoid wear erosion, and adding steel bonded tungsten carbides F3002 prolonged the hammer life- span. The effect of austenitic manganese steel work-hardening was not prominent. Therefore, the hammer failure was mainly caused by superficial abrasion instead of fatigue cracks appearing when grains acted on the hardening layer.
