Using a closed field unbalanced magnetron sputtering system,the cemented carbide end mills were coated with a CrTiAlN hard coating,which consisted of a Cr adhesive layer,a CrN interlayer and a CrTiAlN top layer.The mi...Using a closed field unbalanced magnetron sputtering system,the cemented carbide end mills were coated with a CrTiAlN hard coating,which consisted of a Cr adhesive layer,a CrN interlayer and a CrTiAlN top layer.The microstructure and mechanical properties of the coating were investigated by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,micro indentation and scratch test.The cutting performance of the coated end mills were conducted by high-speed dry milling hardened steel（P20,HRC 45）.The results indicates that the coating is composed of（Cr,Ti,Al）N columnar grains with nanolayers.The coating exhibits good adhesion to cemented carbide substrate and high microhardness of around 30 GPa.The coated end mills show significant improvement on tool life and much lower cutting force as compared to the uncoated ones.And the related mechanisms were discussed.展开更多
Wire+arc additive manufacturing(WAAM)is considered an innovative technology that can change the manufacturing landscape in the near future.WAAM offers the benefits of inexpensive initial system setup and a high deposi...Wire+arc additive manufacturing(WAAM)is considered an innovative technology that can change the manufacturing landscape in the near future.WAAM offers the benefits of inexpensive initial system setup and a high deposition rate for fabricating medium-and large-sized parts such as die-casting tools.In this study,AISI H13 tool steel,a popular die-casting tool metal,is manufactured by cold metal transfer(CMT)-based WAAM and is then comprehensively analyzed for its microstructural and mechanical properties.Location-dependent phase combinations are observed,which could be explained by nonequilibrium thermal cycles that resulted from the layer-by-layer stacking mechanism used in WAAM.In addition,remelting and reheating of the layers reduces welding anomalies(e.g.,pores and voids).The metallurgical characteristics of the H13 strongly correlate with the mechanical properties.The combinations of phases at different locations of the additively manufactured part exhibit a periodic microhardness profile.Martensite,Retained Austenite,Ferrite,and Carbide phases are found in combination at different locations of the part based on the part’s temperature distribution during additive deposition.Moreover,the tensile properties at elevated temperatures(23℃,300℃,and 600℃)are comparable to those from other WAAM and additive manufacturing(AM)processes.The X-ray diffraction results verify that the microstructural stability of the fabricated parts at high temperatures would allow them to be used in high temperatures.展开更多
钢丝试井作业普通防喷堵头密封级数少、安装紧固扭矩大、密封效果差、缺少仪器捕捉功能、磨损防硫钢丝。采取增加一级密封压帽和盘根、将73.025 mm TBG平式油管扣型改为Tr75×4扣型、丝扣缠上聚四氟乙烯带密封更改为双道“O”圈密...钢丝试井作业普通防喷堵头密封级数少、安装紧固扭矩大、密封效果差、缺少仪器捕捉功能、磨损防硫钢丝。采取增加一级密封压帽和盘根、将73.025 mm TBG平式油管扣型改为Tr75×4扣型、丝扣缠上聚四氟乙烯带密封更改为双道“O”圈密封、增加卡瓦捕捉器和保护衬套等措施,研制出一种新型钢丝作业防喷堵头。室内承压试验和捕捉试验成功后,先后选择0~15 MPa井实测30多井次,均获一次成功。2019年大港油田512井次的实际应用表明,新型钢丝作业防喷堵头安全可靠,紧固扭矩降低1.5倍,材料消耗降低5倍,工作效率提高一倍以上,完善了钢丝试井作业工艺,对指导现场试井工作具有一定意义。展开更多
基金Projects (500120069,U1201245) supported by the National Natural Science Foundation of ChinaProject (2011J2200036) supported by Guangzhou Scientific and Technological Planning Project,ChinaProject supported by Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(2012),China
文摘Using a closed field unbalanced magnetron sputtering system,the cemented carbide end mills were coated with a CrTiAlN hard coating,which consisted of a Cr adhesive layer,a CrN interlayer and a CrTiAlN top layer.The microstructure and mechanical properties of the coating were investigated by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,micro indentation and scratch test.The cutting performance of the coated end mills were conducted by high-speed dry milling hardened steel（P20,HRC 45）.The results indicates that the coating is composed of（Cr,Ti,Al）N columnar grains with nanolayers.The coating exhibits good adhesion to cemented carbide substrate and high microhardness of around 30 GPa.The coated end mills show significant improvement on tool life and much lower cutting force as compared to the uncoated ones.And the related mechanisms were discussed.
基金support of the Korea Institute of Industrial Technology as a project on the development of metal 3D printing materials and process optimization technology for medium-and large-sized transportation part mold manufacturing(KITECH JE200008)。
文摘Wire+arc additive manufacturing(WAAM)is considered an innovative technology that can change the manufacturing landscape in the near future.WAAM offers the benefits of inexpensive initial system setup and a high deposition rate for fabricating medium-and large-sized parts such as die-casting tools.In this study,AISI H13 tool steel,a popular die-casting tool metal,is manufactured by cold metal transfer(CMT)-based WAAM and is then comprehensively analyzed for its microstructural and mechanical properties.Location-dependent phase combinations are observed,which could be explained by nonequilibrium thermal cycles that resulted from the layer-by-layer stacking mechanism used in WAAM.In addition,remelting and reheating of the layers reduces welding anomalies(e.g.,pores and voids).The metallurgical characteristics of the H13 strongly correlate with the mechanical properties.The combinations of phases at different locations of the additively manufactured part exhibit a periodic microhardness profile.Martensite,Retained Austenite,Ferrite,and Carbide phases are found in combination at different locations of the part based on the part’s temperature distribution during additive deposition.Moreover,the tensile properties at elevated temperatures(23℃,300℃,and 600℃)are comparable to those from other WAAM and additive manufacturing(AM)processes.The X-ray diffraction results verify that the microstructural stability of the fabricated parts at high temperatures would allow them to be used in high temperatures.
文摘钢丝试井作业普通防喷堵头密封级数少、安装紧固扭矩大、密封效果差、缺少仪器捕捉功能、磨损防硫钢丝。采取增加一级密封压帽和盘根、将73.025 mm TBG平式油管扣型改为Tr75×4扣型、丝扣缠上聚四氟乙烯带密封更改为双道“O”圈密封、增加卡瓦捕捉器和保护衬套等措施,研制出一种新型钢丝作业防喷堵头。室内承压试验和捕捉试验成功后,先后选择0~15 MPa井实测30多井次,均获一次成功。2019年大港油田512井次的实际应用表明,新型钢丝作业防喷堵头安全可靠,紧固扭矩降低1.5倍,材料消耗降低5倍,工作效率提高一倍以上,完善了钢丝试井作业工艺,对指导现场试井工作具有一定意义。
