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
Φ6.5 mm SWRCH45K盘条经球化退火,在冷镦过程中开裂。对盘条进行金相检验,钢中夹杂物总级别为2级,未发现大型夹杂物,盘条显微组织出现局部偏析和魏氏组织。采用热模拟试验,将6.5 mm SWRCH45K盘条分别加热到860,900℃,并分别进行炉冷...Φ6.5 mm SWRCH45K盘条经球化退火,在冷镦过程中开裂。对盘条进行金相检验,钢中夹杂物总级别为2级,未发现大型夹杂物,盘条显微组织出现局部偏析和魏氏组织。采用热模拟试验,将6.5 mm SWRCH45K盘条分别加热到860,900℃,并分别进行炉冷、空冷、吹风冷却,对SWRCH45K盘条的显微组织和晶粒度进行分析。结果表明:采用860℃加热并炉冷后,其显微组织为铁素体与珠光体,基本上未形成魏氏组织,晶粒度较均匀。提出适当调整精轧、终轧与吐丝温度,降低斯太尔摩线的辊道速度,可消除魏氏组织,改善偏析与晶粒不均匀现象。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.
文摘Φ6.5 mm SWRCH45K盘条经球化退火,在冷镦过程中开裂。对盘条进行金相检验,钢中夹杂物总级别为2级,未发现大型夹杂物,盘条显微组织出现局部偏析和魏氏组织。采用热模拟试验,将6.5 mm SWRCH45K盘条分别加热到860,900℃,并分别进行炉冷、空冷、吹风冷却,对SWRCH45K盘条的显微组织和晶粒度进行分析。结果表明:采用860℃加热并炉冷后,其显微组织为铁素体与珠光体,基本上未形成魏氏组织,晶粒度较均匀。提出适当调整精轧、终轧与吐丝温度,降低斯太尔摩线的辊道速度,可消除魏氏组织,改善偏析与晶粒不均匀现象。
