Conventionally manufactured 35CrMo cold heading steel must undergo spheroidization annealing before the cold heading process In this paper, different types of deformation processes with various controlled cooling peri...Conventionally manufactured 35CrMo cold heading steel must undergo spheroidization annealing before the cold heading process In this paper, different types of deformation processes with various controlled cooling periods were operated to achieve on-line spheroidal cementite using the Gleeble-3500 simulation technique. According to the measured dynamic ferrite transformation temperature （Ad3）, the deformation could be divided into two types： low temperature deformation at 810 and 780℃; ＂deformation-induced ferrite transformation＂ （DIFT） deformation at 750 and 720℃. Compared with the low temperature deformation, the DIFT deformation followed by accelerated cooling to 680℃ is beneficial for the formation of spheroidal cementite. Samples subjected to both the low-temperature deformation and DIFT deformation can obtain granular bainite by accelerated cooling to 640℃; the latter may contribute to the formation of a fine dispersion of secondary constituents. Granular bainite can transform into globular pearlite rapidly during subcritical annealing, and the more the disperse phase, the more homogeneously distributed globular cementite can be obtained.展开更多
Cold heading carbon steels for 8.8 grade fasteners are mostly produced by pouring reel or spooler plant.Currently,with improvement of cold heading equipment,the 10.9 grade fasteners produced by cold heading have repla...Cold heading carbon steels for 8.8 grade fasteners are mostly produced by pouring reel or spooler plant.Currently,with improvement of cold heading equipment,the 10.9 grade fasteners produced by cold heading have replaced most of hot forged fasteners gradually.As well known,wire rod coil has been used to produce alloy steels.The properties and microstructures of medium carbon alloy steels,such as B7,ML40Cr and SCM435,produced by wire rod coils under hot rolled condition and after spheroidization,have been investigated.In this paper,the effect of microstructure of hot rolled steel wire rods on cold heading annealing process was studied.The results show that the hardness of wire rod coil products is generally lower than that of bar products by 5 ～ 10 HRB and the ferrite fraction in wire rod coil products is higher.After spheroidization treatment,the hardness value and spheroidization grade of wire rod coil products are relatively low.alloy steels of wire rod coils can be directly drawn slightly and the annealing time can be reduced at the same time.This practice is much helpful for energy conservation.展开更多
对150 mm×150 mm连铸坯轧制Φ12 mm SCM435合金冷镦钢(%:0.35C、0.98Cr、0.16Mo)盘条的工艺试验表明:采用1020℃加热,900℃轧制,吐丝温度控制在780～800℃,相变前冷却速度控制在1℃/s左右,该钢可以获得均匀的铁素体+珠光体组织和...对150 mm×150 mm连铸坯轧制Φ12 mm SCM435合金冷镦钢(%:0.35C、0.98Cr、0.16Mo)盘条的工艺试验表明:采用1020℃加热,900℃轧制,吐丝温度控制在780～800℃,相变前冷却速度控制在1℃/s左右,该钢可以获得均匀的铁素体+珠光体组织和良好的冷镦性能。展开更多
文摘Conventionally manufactured 35CrMo cold heading steel must undergo spheroidization annealing before the cold heading process In this paper, different types of deformation processes with various controlled cooling periods were operated to achieve on-line spheroidal cementite using the Gleeble-3500 simulation technique. According to the measured dynamic ferrite transformation temperature （Ad3）, the deformation could be divided into two types： low temperature deformation at 810 and 780℃; ＂deformation-induced ferrite transformation＂ （DIFT） deformation at 750 and 720℃. Compared with the low temperature deformation, the DIFT deformation followed by accelerated cooling to 680℃ is beneficial for the formation of spheroidal cementite. Samples subjected to both the low-temperature deformation and DIFT deformation can obtain granular bainite by accelerated cooling to 640℃; the latter may contribute to the formation of a fine dispersion of secondary constituents. Granular bainite can transform into globular pearlite rapidly during subcritical annealing, and the more the disperse phase, the more homogeneously distributed globular cementite can be obtained.
文摘Cold heading carbon steels for 8.8 grade fasteners are mostly produced by pouring reel or spooler plant.Currently,with improvement of cold heading equipment,the 10.9 grade fasteners produced by cold heading have replaced most of hot forged fasteners gradually.As well known,wire rod coil has been used to produce alloy steels.The properties and microstructures of medium carbon alloy steels,such as B7,ML40Cr and SCM435,produced by wire rod coils under hot rolled condition and after spheroidization,have been investigated.In this paper,the effect of microstructure of hot rolled steel wire rods on cold heading annealing process was studied.The results show that the hardness of wire rod coil products is generally lower than that of bar products by 5 ～ 10 HRB and the ferrite fraction in wire rod coil products is higher.After spheroidization treatment,the hardness value and spheroidization grade of wire rod coil products are relatively low.alloy steels of wire rod coils can be directly drawn slightly and the annealing time can be reduced at the same time.This practice is much helpful for energy conservation.
