中碳钢球化退火行为和力学性能的研究

采用常规双相区球化退火和亚温球化退火工艺研究了常规轧制（CR）和控轧控冷（CRC）的中碳钢SWRCH35K的球化退火行为和力学性能。结果表明,与传统的双相区球化退火相比,亚温球化退火时碳化物球化进程明显加快,球化率高,且碳化物比较细小,具有良好的塑性和冷成形性,采用亚温球化退火处理可明显地缩短球化退火时间。控轧控冷的中碳钢线材尽管具有比较粗大的珠光体组织,但因有相当部分的珠光体发生退化,其球化退火进程要明显快于细珠光体组织。     

高碳铬轴承钢棒材轧后控冷工艺

阐述了轧后控冷工艺的机理,介绍了在特殊钢分公司连轧棒材线上运用轧后控冷技术,细化高碳铬轴承钢球化前的预备组织,获得片层间距较细的片状珠光体,在球化退火后,组织均匀细小,可获得细小弥散的碳化物颗粒,使网状碳化物级别≤2.5级,保证了产品质量。运用轧后控冷技术代替正火工艺,降低了生产成本。     

GCr15球化退火行为和力学性能的研究

采用等温球化退火和周期球化退火工艺分别研究了常规轧制（CR）和控轧控冷（TMCP）的GCr15钢的球化退火行为和力学性能。结果表明,轧制工艺对GCr15钢组织影响显著;在等温球化退火处理制度下常规轧制（CR）和控轧控冷（TMCP）试样球化效果差别较小;在周期球化退火处理制度下,控轧控冷（TMCP）试样可获得细小均匀的球化组织,其球化效果明显优于常规轧制（CR）试样,且球化退火时间比宝钢特钢现行的等温球化退火工艺缩短了6 h,可显著提高生产效率。     

受热不均匀对低碳钢SAE1010板材组织及成形性能的影响

为了研究退火过程受热不均匀对板材组织及成形性能的影响规律,对热轧态SAE1010低碳钢板进行冷轧及连续退火,分析热轧态、冷硬态及退火态钢板边部和芯部的显微组织,分别对退火态钢板边部和芯部试样进行拉伸和折弯试验。结果表明,热轧态试样少量岛状珠光体分布在铁素体晶界处,边部组织晶粒尺寸小于芯部,珠光体中部分片层渗碳体退化为球状。冷硬态板材组织沿轧制方向呈现明显的晶粒破碎特征,退火态边部组织存在较多的大晶粒和粒状渗碳体团,芯部组织较为均匀细小。退火态板材芯部材料伸长率高于边部而强度低于边部,经180°折弯后芯部钢板无开裂而边部出现裂纹。退火温度均匀性对于SAE1010低碳钢板组织和性能具有重要的影响。     

共析碳工具钢球化珠光体新工艺的研究

大连钢厂对难以得到均匀细小粒状珠光体的共析碳工具,找到了一种新工艺。这种工艺包括两个步骤:(1)利用锻轧余热沸水淬火取得极细索氏体组织。(2)在不发生相变的温度下退火得到均匀细小的粒状珠光体。     

F40MnV钢冷却曲线的现场测定及珠光体相变点判定方法研究

介绍了F40MnV钢在现场条件下珠光体相变点的测定及分析方法,可对非调质钢冷却工艺的控制提供控冷参考,以便获得最佳的组织和性能.     

生产工艺对65Mn冷轧钢带组织性能的影响

对不同生产工艺下冷轧态及退火态65Mn钢带的组织和退火态钢带的力学性能进行了分析。未经退火的65Mn钢冷轧时,珠光体组织以弯曲变形为主,随着总变形率的增加,珠光体弯曲变形减少,片层细化变形成为主要变形方式;经预退火的65Mn钢冷轧时,珠光体组织变形均以细化变形为主。采用原料经预退火后再进行冷轧的工艺生产的65Mn退火钢带组织均匀,力学性能稳定,塑性较好。     

控冷工艺对82B盘条相变行为影响的研究

利用Gleeble-3800热模拟试验机分别测定了82B盘条在静态和控冷状态下的CCT曲线,研究了控冷工艺对82B盘条相变行为和组织转变的影响。结果表明,与静态CCT相比,控冷工艺能够推迟珠光体转变,降低临界冷却速率,并且能够优化组织;相变时的最佳冷却速率应控制在3℃／s以下。     

控冷工艺对钢材组织与性能的影响

对焊接结构钢HG70,HG785钢运用实验室模拟热处理工艺,制定合理的控冷+回火热处理制度,并进行力学性能检验和金相组织检验,探索焊接结构钢在控冷状态下性能合格率不高的原因.试验结果表明,快速冷却的控冷工艺使钢板组织中存在马氏体,是造成钢板塑性、韧性下降,冲击吸收功不稳定的主要原因,并且钢板厚度方向晶粒度不一致.必须通过对轧后控冷钢板的回火处理,消除马氏体,得到均匀化组织,提高钢材性能合格率.     

薄规格Q370qE钢板TMCP工艺开发及应用

考虑到薄规格Q370qE桥梁用钢板低温韧性及焊接性能要求,此钢种采用低碳成分设计,同时添加Nb等细化晶粒的微合金元素.为满足钢板强度需求,钢板采用控轧控冷工艺生产,通过合理的工艺控制,最终实现了钢板全厚度方向均匀的铁素体+珠光体组织,钢板性能优良,平直度良好.     

Effect of process parameters on microstructure and mechanical properties of non- annealed cold heading steel SWRCH35KM

In order to realize the on- line softening treatment of non- annealed cold heading steel SWRCH35KM, the influence of controlled rolling and controlled cooling process on the microstructure and mechanical properties of medium carbon cold heading steel was investigated. The results show that the microstructures of spherular pearlite dispersed in 60%-63% ferrite matrix are obtained after step slow cooling process. With the decrease of finish rolling temperature from 850?? to 750??, ferrite grain size refines from 15-16. 9??m to about 10??m, and spheroidization of pearlite tends to significantly. Tensile strength of test steel with step slow cooling process is about 490-510MPa, elongation is 36. 5%-40. 5%, and hardness is 73HRB-78HRB. Compared with the air cooling process, the tensile strength of test steel decreases by about 30-40MPa, elongation increases by 1%-3% and hardness decreases by about 2HRB-3HRB.     

Effect of Ultra-Fast Cooling on Microstructure of Large Section Bars of Bearing Steel

The ultra-fast cooling technology of large section bars and the microstructure for different cooling patterns were studied by optical microscope, transmission electron microscope and energy spectrometer. The results indicated that the large section bars were passed through the zone of secondary carbide precipitation quickly by ultra-fast cooling technology (UFC) at instantaneous cooling rate of about 200 ℃/s and the finishing cooling temperature was higher than M,. The lamellar spacing of pearlite decreased and the microhardness increased with decreasing the re-reddening temperature. The precipitation of network carbide was restrained when rereddening temperature was 690 ℃. And fine laminated pearlite was obtained through transformation of pseudopearlition that induced the reduction of the diameter of pearlite grain and refinement of the lamellar spacing of pearlite, so ideal microstructures of promoting spheroidizing annealing were obtained.     

Effects of Rolling and Cooling Conditions on Microstructure and Mechanical Properties of Low Carbon Cold Heading Steel

 Effects of rolling and cooling conditions on microstructure and mechanical properties of low carbon cold heading steel were investigated on a laboratory hot rolling mill. The results have shown that the mechanical properties of low carbon steels exceed the standard requirements of ML30, ML35, ML40, and ML45 steel, respectively due to thermomechanical controlled processing (TMCP). This is attributed to a significant amount of pearlite and the ferrite-grain refinement. Under the condition of relatively low temperature rolling, the mechanical properties exceed standard requirements of ML45 and ML30 steel after water cooling and air cooling, respectively. Fast cooling which leads to more pearlite and finer ferrite grains is more critical than finish rolling temperatures for low carbon cold heading steel. The specimen at high finish rolling temperature exhibits very good mechanical properties due to fast cooling. This result has great significance not only for energy saving and emission reduction, but also for low-carbon economy, because the goals of the replacement of medium-carbon by low-carbon are achieved with TMCP.     

Effect of Ultra-fast cooling on the microstructure of large-section bars of bearing steel

 The ultra-fast cooling technology of large-section bars GCr15 bearing steel was researched connected with industry practice, the microstructure in different cooling patters were researched by optical microscopy、transmission electron microscopy and energy spectrometer, it was concluded that: the large-section bars of GCr15 bearing steel passed the zone of secondary carbide precipitation quickly through the ultra-fast cooling technology(UFC) the instantaneous cooling rate of which was about 200℃/s, the finishing cooling temperature was higher than Ms, the lamellar spacing of pearlite was thinner and thinner and the micro-hardness was bigger and bigger along with the reduction of re-reddening temperature,the precipitation of network carbide was restrained when re-reddening temperature was 690℃, and fine laminated pearlite was obtained through transformation of pseudopearlition which induced the reduction of the diamond of pearlite grain and refinement of the lamellar spacing of pearlite, ideal microstructures promoting spheroidizing annealing were obtained.     

冷镦钢SWRCH35K的控轧控冷工艺

介绍了控轧控冷参数是影响冷镦钢SERCH35K金相组织和机械性能的重要因素．提出了确定该钢种控轧控冷工艺的具体参数。     

免热处理高强度低屈强比铆螺钢的研究

铆螺钢经棒材轧机控轧控冷轧成棒材,获得具有铁素体、珠光体和粒状贝氏体的混合组织,冷镦成螺栓后进行产品检验.结果表明:控轧控冷后的棒材不经过退火直接冷镦成螺栓,冷镦性能非常好.螺栓不经过最终热处理,同样可获得很高的力学性能.力学性能的提高主要是由于螺栓在拉伸变形时残余奥氏体的应变诱导马氏体相变.     

SCM435冷镦钢奥氏体连续冷却转变曲线研究

利用Gleeble-3800热模拟试验机,采用热膨胀法结合硬度测量,研究了SCM435冷镦钢的连续冷却转变过程,通过光学显微镜、电子探针分析了不同冷速下SCM435冷镦钢的组织转变行为。结果表明,SCM435冷镦钢冷速低于1℃/s时,组织主要为铁素体+珠光体+贝氏体,在1~10℃/s冷速范围内,组织主要为贝氏体和少量珠光体+铁素体或马氏体,冷速大于10℃/s时,组织为马氏体。     

冷却模式对铸坯表面组织的影响

 制作直径10mm的试样以模拟铸坯表面组织,将试样分别在传统冷却模式下和控制冷却模式下进行冷却,通过对试样截面的微观组织形貌进行金相分析,从而研究冷却模式对铸坯表层组织结构的影响。试验得到如下结果：传统冷却条件下,试样边部为块状铁素体和珠光体,晶粒尺寸在10~200μm之间,中心位置为条状、针状铁素体和珠光体,晶粒粗大,组织不均。控制冷却条件下,试样均由块状铁素体和珠光体组成,晶粒尺寸在9.36~12.25μm之间,晶粒细小,组织均匀。控制冷却可以通过细化晶粒来提高铸坯表面的高温塑性从而对避免表面横裂纹的发生产生有利影响。     

60Si2Mn弹簧钢的柔性轧制技术

通过调整终轧温度,研究了冷却速度对60Si2Mn钢相变组织及力学性能的影响。结果表明：终轧温度和冷却速度的变化对60Si2Mn钢显微组织和性能有显著的影响,在相同的终轧温度下,随冷却速度增大铁素体组织和珠光体片层间距得到细化,索氏体含量提高,硬度逐渐增加。