稀土对14MnNb钢的微合金化作用

14MnNb钢在轧制态下,随着固溶稀土增加,碳化铌析出增加,颗粒变小且弥散分布,珠光体星球状、数量减少。当固溶稀土含量为174×10^-6时,板条状贝氏体变为粒状贝氏体组织。在奥氏体区,稀土使碳化铌析出的孕育期延长,有抑制碳化铌析出的作用。固溶稀土推迟了再结晶的动力学过程,并使马氏体组织变细。     

薄板坯连铸连轧工艺对铌微合金化高强度钢组织和性能的影响

首先建立薄板坯连铸连轧工艺的试验室模拟技术，并运用该模拟技术，研究薄板坯连铸连轧工艺(CSP)和传统板坯再加热工艺(TRP)两种工艺对铌微合金化高强度钢的显微组织和力学性能的影响。研究结果表明：CSP钢的晶粒细化效果不如TRP钢，两者的平均铁素体晶粒尺寸分别为8．17μm和6．30μm。在CSP试验钢板中铌的析出量较大，特别是在铁素体中细小颗粒的铌的析出物较多，沉淀强化效果较强。CSP试验钢的σ0.5和σb分别较TRP工艺低约40MPa和约25MPa，同时其低温冲击韧性较好，FATT温度较低。     

N对V-微合金化钢15MnVq的组织和性能的影响

通过100 kg真空感应炉,分别添加V-N合金和V-Fe合金熔炼成15MnVNq钢(%-0.15C、1.71Mn、0.11V、0.019 ON)和15MnVq钢(%:0.15C、1.72Mn、0.11V、0.003 3N),并轧制成14 mm钢板.试验结果表明,15MnVq钢中加入0.019%的N促进V(C,N)析出和明显细化钢的组织,钢的屈服和抗拉强度分别由393 MPa和578 MPa提高至510 MPa和660 MPa,-20℃冲击功AKV由21.9 J提高到101.8 J;同时加N后明显降低了15MnVq钢的时效敏感性.     

卷取温度对微合金化含磷钢薄钢板组织和性能的影响

以低碳微合金化含磷钢为研究对象,通过分析热轧态和冷轧退火态的显微组织和力学性能以及退火再结晶动力学行为,研究了卷取温度(600、650、700℃)对微合金化含磷钢组织和性能的影响.研究结果表明,热轧卷取温度对微合金化含磷钢的显微组织和力学性能有显著的影响,随着热轧卷取温度从700℃降低到600℃,试验钢退火再结晶受到明显延迟,再结晶激活能明显提高;卷取温度对热轧态和退火态铁素体晶粒尺寸影响较小,但热轧态强度随着卷取温度降低而提高;随着卷取温度的降低,冷轧退火态的强度提高,且力学性能对退火温度的敏感性增加.     

稀土对20MnVB钢组织性能的影响

本文试验研究了稀土对２０ＭｎＶＢ钢硫化物和氧化物的变质作用，以及对组织和性能的影响。结果得出ＲＥ／Ｓ为１．８～２．５时，２０ＭｎＶＢ钢具有最佳的组织和综合性能。     

Effects of Lanthanum on Mechanical Properties of 5CrNiMo Forging Die Steel

The alteration of the strength, hardness and impact ductility of 5CrNiMo steel using three different additions of RE La element is studied in this paper. The mechanical properties of 5CrNiMo steel with RE La additions are be compared with that of the 5CrNiMo steel on the same heat-treatment condition without RE La element addition. The results show that the strength. hardness and impact ductility of 5CrNiMo steel will be improved obviously when the content of RE La element is proper, and as the content of RE La element is 0.033% (mass fraction), the 5CrNiMo steel has the best mechanical properties.     

Effect of Microalloying Additions on the Microstructure and Mechanical Properties of Low Carbon Steel

Low carbon steels are characterized by good weldability,formability and fracture toughness properties.However,the low strength levels of these steel grades limit their wide applications.On the other hand,increasing the strength by increasing the carbon content and alloying elements deteriorates the other properties.In this study,the microalloying technique was used to examine the possibility of attaining low carbon steels with good combination of strength,ductility and impact properties.A low carbon steel microalloyed with single addition of vanadium and another one microalloyed with combined addition of vanadium and titanium were used in this investigation and their properties were compared with non-microalloyed low carbon steel having the same base composition.Furthermore,other two nonmicroalloyed and V-microalloyed steels with higher carbon,silicon and manganese contents were also investigated to reveal the effect of base composition.Tensile,hardness,room and zero temperature Charpy V-notch impact tests were conducted to evaluate the variations in the mechanical properties of low carbon hot forged steel containing vanadium and combinations of vanadium and titanium.In addition,the microstructures of the different investigated steels were observed using both optical microscope and scanning electron microscope.Furthermore,the hardness of the ferrite phase was also determined using micro-hardness technique.The results showed improvement of the mechanical properties of the investigated steels by both single V-and combined V + Ti-microadditions.Tensile,hardness and impact tests results indicated that good combinations of strength,ductility and impact properties can be achieved by V-microalloying addition.Steel with combination of V and Ti microaddition has much higher hardness,yield strength,ultimate tensile strength and impact energy at both room and zero temperatures compared with non-microalloyed and single Vmicroalloyed steels.Higher C,Si and Mn contents result in increasing the strength accompanied with decrea     

Effects and Mechanisms of RE on Impact Toughness and Fracture Toughness of Clean Heavy Rail Steel

 Clean high carbon heavy rail steel was prepared by the process of vacuum induction furnace smelting, forging and rolling. Mechanisms of RE on the impact toughness and fracture toughness for clean high carbon steel were investigated. In addition, the appropriate range of RE content for clean high carbon steel was determined. Both the austenite grain size and pearlite lamellar spacing decreased due to small amount of RE, consequently the impact toughness and fracture toughness were improved evidently. When the RE content exceeded a critical value, the pearlite lamellar spacing was increased, because RE was segregated on the austenite grain boundaries, damaged the orientation relationship of pearlite transformation, caused the disorder growth and morphology degenerating of pearlite. With the increasing of RE content, both the impact toughness and fracture toughness of clean high carbon steel were gradually increased at first and then decreased. It was found that when the RE content was between 00081% and 00088%, both the impact toughness and fracture toughness of clean high carbon heavy rail steel were the best. The maximum ballistic work was 212 J (20 ℃) and 122 J (-20 ℃), respectively. The maximum plane-strain fracture toughness was 4567 MPa·m1/2 (20 ℃) and 3704 MPa·m1/2 (-20 ℃), respectively.     

钒对18Cr-2Mo铁素体不锈钢性能的影响

 利用Thermo-Calc热力学软件、扫描电子显微镜、X射线衍射仪及透射电镜等分析方法,研究了不同钒含量对单铌稳定18Cr-2Mo铁素体不锈钢微观组织、力学性能和点腐蚀性能的影响规律。结果表明：添加钒后的析出相主要是NbC和VN,弥散分布于晶内和晶界,其中NbC的尺寸为100~250nm;随着钒含量的增加,试验钢的晶粒尺寸及屈服强度变化不明显,而冲击韧性及点腐蚀性能逐步得到改善和提高,当wV=0.36%时,钢的韧脆?湮露扔稍嫉?10℃下降至-30℃,点腐蚀电位由0.38V提高至0.42V。     

稀土La对5CrNiMo模具钢力学性能的影响

研究了加入稀土La后5CrNiMo钢的强度、硬度、冲击韧性变化;并在相同热处理工艺条件下,与不添加稀土La的5CrNiMo钢进行对比.结果表明:稀土La加入量在适当的范围内可显著提高钢的强度、硬度和冲击韧性;当稀土La质量分数为0.033%时,5CrNiMo钢可获得最好的综合力学性能.     

铌对00Crl2Ni不锈钢组织和性能的影响

分别冶炼了3种不同铌含量的00Crl2Ni不锈钢,用光学显微镜和透射电镜观察了热轧退火态的显微组织,测量了试验钢的拉伸性能和不同温度的冲击功。试验结果表明：铌的添加显著抑制了退火时铁素体再结晶的发生。未添加稳定化元素铌的钢中析出相为cr23Cr23C6,ω（Nb）为0．28％的试验钢中析出相为Nb（C,N）和Fe3Nb3C,ω（Nb）为0．49％的试验钢中析出相为Nb（C,N）和FezNb,而且其析出相总体积分数明显高于其他2种试验钢。铌的添加提高了试验钢的强度,降低了试验钢的塑性和韧性,ω（Nb）为0．49％的试验钢冲击功最低,但其韧脆转变温度也最低。     

Microstructure,Tensile and Impact Toughness Properties of Friction Stir Welded Mild Steel

 Microstructure, tensile and impact toughness properties and fracture location of friction stir welded AISI 1018 mild steel are revealed in this paper. The 5 mm thick AISI 1018 mild steel plates were friction stir welded with tool rotational speed of 1000 rpm and welding speed of 50 mm/min with tungsten base alloy tool. Tensile strength of stir zone is higher (8%) when compared to the base metal. This may be due to the formation of finer grains in the weld nugget region under the stirring action of the rotating tool. The ductility and impact toughness of the joints are decreased compared to the base metal and this is due to the inclusion of tungsten particles in the weld region.     

微钛处理对含磷钢薄钢板组织和性能的影响

以低碳含磷钢为研究对象,通过分析不同卷取温度时(分别为600、650和700 ℃)热轧态和冷轧退火态的显微组织和力学性能以及退火再结晶动力学行为,研究了微钛(0.015%)处理对钢的组织和性能的影响.研究结果表明,热轧卷取温度对低碳含磷钢的显微组织和力学性能影响很小,但微钛处理后,低碳含磷钢的再结晶动力学受到延迟,特别当卷取温度为600 ℃时,不但热轧态和冷轧退火态的强度提高,而且力学性能对卷取温度和退火温度的敏感性增加;随着卷取温度的降低,热轧态和冷轧退火态的强度提高,且冷轧退火态强度随着退火温度升高而降低的幅度增加.微钛处理对含磷钢组织和性能的影响与钛析出相的粗化行为有关.     

铌对00Cr12Ni不锈钢组织和性能的影响

 分别冶炼了3种不同铌含量的00Cr12Ni不锈钢,用光学显微镜和透射电镜观察了热轧退火态的显微组织,测量了试验钢的拉伸性能和不同温度的冲击功。试验结果表明：铌的添加显著抑制了退火时铁素体再结晶的发生。未添加稳定化元素铌的钢中析出相为Cr23C6,w(Nb)为0.28%的试验钢中析出相为Nb(C,N)和Fe3Nb3C,w(Nb)为0.49%的试验钢中析出相为Nb(C,N)和Fe2Nb,而且其析出相总体积分数明显高于其他2种试验钢。铌的添加提高了试验钢的强度,降低了试验钢的塑性和韧性,w(Nb)为0.49%的试验钢冲击功最低,但其韧脆转变温度也最低。