The effect of friction pressure p and oxygen concentration xo on the fireproof performance of Ti40 titanium alloy was studied by frictional ignition test, the U--Xo relationship quantitatively describing the fireproof...The effect of friction pressure p and oxygen concentration xo on the fireproof performance of Ti40 titanium alloy was studied by frictional ignition test, the U--Xo relationship quantitatively describing the fireproof performance of Ti40 was established and the fireproof mechanism of Ti40 was analyzed by SEM, XRD and EDS. The results show that the p--xo relationship of Ti40 obeys parabolic rule. The varying range of xo is about 25% while p varies within 0.1-0.25 MPa. When Xo is 〉70%, Ti40 is ignited immediately at room temperature and develops into continual and steady burning, and the duration of burning is more than 10 s. The fireproof performance of Ti40 is better than TC4 while xo of Ti40 is at least 40% higher than TC4. When Xo is low, the fireproof performance of Ti40 is more sensitive to p; when Xo increases, it is more sensitive to Xo. The forming of fused oxides of V205, TiO2 and Cr203 with strong inner interaction during friction is the basic reason of high fireproof performance of Ti40.展开更多
Massive vanadium additions as hard phases in powder metallurgy high-speed steels(PM HSS)lead to higher cost and bad machinability.In this study,ultrahigh alloy PM HSS with CPM121(10W-5Mo-4Cr-10V-9Co,wt.%)as the basic ...Massive vanadium additions as hard phases in powder metallurgy high-speed steels(PM HSS)lead to higher cost and bad machinability.In this study,ultrahigh alloy PM HSS with CPM121(10W-5Mo-4Cr-10V-9Co,wt.%)as the basic composition,was directly compacted and activation sintered with near-full density(>99.0%)using pre-oxidized and ball-mixed element and carbide powders.Niobium-alloyed steels(w(V)+w(Nb)=10 wt.%)show higher hardness and wear resistance,superior secondary-hardening ability and temper resistance.But excess niobium addition(>5 wt.%)leads to coarsened carbides and deteriorated toughness.EPMA results proved that niobium tends to distribute in MC carbides and forces element W to form M6C and WC carbides.Further,the role of rotary forging on properties of niobium-alloyed steels(S3)was researched.After rotary forging with deformation of 40%,the bending strength and fracture toughness of niobium-alloyed steels could be further improved by 20.74%and 43.86%compared with those of sample S3 without rotary forging,respectively.展开更多
基金Project(20123021004) supported by the Key Program of the Aeronautical Science Foundation of ChinaProject(51312030501) supported by the Pre-Research Program of China
文摘The effect of friction pressure p and oxygen concentration xo on the fireproof performance of Ti40 titanium alloy was studied by frictional ignition test, the U--Xo relationship quantitatively describing the fireproof performance of Ti40 was established and the fireproof mechanism of Ti40 was analyzed by SEM, XRD and EDS. The results show that the p--xo relationship of Ti40 obeys parabolic rule. The varying range of xo is about 25% while p varies within 0.1-0.25 MPa. When Xo is 〉70%, Ti40 is ignited immediately at room temperature and develops into continual and steady burning, and the duration of burning is more than 10 s. The fireproof performance of Ti40 is better than TC4 while xo of Ti40 is at least 40% higher than TC4. When Xo is low, the fireproof performance of Ti40 is more sensitive to p; when Xo increases, it is more sensitive to Xo. The forming of fused oxides of V205, TiO2 and Cr203 with strong inner interaction during friction is the basic reason of high fireproof performance of Ti40.
基金Projects(51771237,51704257)supported by the National Natural Science Foundation of ChinaProject(2019JJ60019)supported by the Joint Fund of Hunan Province,ChinaProject(17QDZ25)supported by the School Level Fund of Xiangtan University,China。
文摘Massive vanadium additions as hard phases in powder metallurgy high-speed steels(PM HSS)lead to higher cost and bad machinability.In this study,ultrahigh alloy PM HSS with CPM121(10W-5Mo-4Cr-10V-9Co,wt.%)as the basic composition,was directly compacted and activation sintered with near-full density(>99.0%)using pre-oxidized and ball-mixed element and carbide powders.Niobium-alloyed steels(w(V)+w(Nb)=10 wt.%)show higher hardness and wear resistance,superior secondary-hardening ability and temper resistance.But excess niobium addition(>5 wt.%)leads to coarsened carbides and deteriorated toughness.EPMA results proved that niobium tends to distribute in MC carbides and forces element W to form M6C and WC carbides.Further,the role of rotary forging on properties of niobium-alloyed steels(S3)was researched.After rotary forging with deformation of 40%,the bending strength and fracture toughness of niobium-alloyed steels could be further improved by 20.74%and 43.86%compared with those of sample S3 without rotary forging,respectively.
