裂解连杆用高强度非调质钢的研制

设计了用于裂解连杆的高强度非调质钢及其生产工艺,通过金相显微镜、扫描电镜等方法,分析了钢的显微组织、析出相及其对力学性能的影响。结果表明:组织由铁素体和珠光体组成,向钢中添加高的V和N元素,有利于增加更多的弥散析出相,提高其强度。轧后加速冷却,有利于铁素体晶粒细化、珠光体球团尺寸和珠光体片层间距减少、析出相增多,使其抗拉强度和屈服强度分别达到1 000 MPa和750 MPa以上。     

钒氮非调质钢的组织变化特征

利用光学显微镜、扫描和透射电镜观察和分析了不同钒、氮含量非调质钢经奥氏体热变形后以不同速度冷却到室温的显微组织.结果表明,随氮含量增加或钒含量减少,珠光体增多;钢中有大量的不仅在先共析铁素体且在珠光体铁素体中析出的小于3 nm的纳米级析出相;冷速增加,铁素体变细且数量减少,继而出现贝氏体、马氏体,同时钒、钛的析出相尺寸变小,成分由以(Ti,V)N为主,转以(Ti,V)C为主.     

45V钢的显微组织与强化关系的研究

探讨了中碳非调质钢45V的强化机制与显微组织间的关系,测定了显微组织参数,观察并分析了沉淀物的形态及其结构。结果表明,加入微量钒的中碳非调质钢,热加工后的空冷组织是由先析铁素体和珠光体组成。在先析铁素体和珠光体的铁素体内部,有细小碳(氮)化物质点析出,这种析出物的颗粒多数在200(?)左右。这些小粒子引起铁素体强化。计算结果表明,随着冷却速度的提高,中碳非调质钢的沉淀强化和珠光体强化效果均趋于增加。     

直接切削用钒钛复合非调质钢的生产实践

探讨了直接切削用钒钛复合非调质钢的生产及质量情况,通过对冶炼、连铸和控轧控冷轧制过程中的工艺参数进行调控优化,获取的非调质钢显微组织为铁素体和珠光体,其抗拉强度817-845 MPa,屈服强度535-581 MPa,冲击功48-60 J,布氏硬度约250 HBW,综合性能优异,产品质量稳定.     

退火工艺对TRIP钢组织和性能的影响

通过实验室模拟热处理的方法对TRIP780钢组织与力学性能进行了研究。结果表明:随着钢带运行速度的增加,多边形铁素体体积分数降低,铁素体平均晶粒尺寸增加,贝氏体含量增加。组织中残余奥氏体含量大体呈增长的趋势,残余奥氏体中碳含量基本呈下降的趋势。钢板的抗拉强度逐渐增加,屈服强度和屈强比都是先减小后增大。随着两相区退火温度的提高,铁素体含量逐渐减少,贝氏体的含量逐渐增加,粗大的再结晶铁素体也逐渐被细小的次生铁素体所取代,残余奥氏体量和残奥中的碳含量先随着加热温度的升高而降低,达到一个低谷以后,再随加热温度的升高而增加,抗拉强度、屈服强度和屈强比规律性不是很强。     

汽车裂解连杆用高强度非调质钢组织和性能的研究

采用金相显微镜、扫描电镜和透射电镜等分析方法, 研究了Rm≥1 000 MPa、ReL≥750 MPa的高强度非调质钢的组织和性能.结果表明:材料为铁素体-珠光体组织,铁素体呈网状分布;珠光体片层间距对强度的影响较大,当片层间距从207 nm减少到171 nm时,屈服强度从 820 MPa上升到840 MPa;其析出第...     

中碳非调质钢的显微组织与强化关系的研究

探讨了中碳非调质钢的强化机构与显微组织间的关系。测定了显微组织参数,观察并分析了沉淀物的形态及其结构。结构表明,加入微量钒的中碳非调质钢热加工后的空冷组织,是由先共析铁素体和珠光体所组成。在先共析铁素体和珠光体的铁素体内部,有细小碳(氮)化物质点析出,这种析出物的粒度多数在200A左右。这些小粒子引起铁素体强化。计算结果证明,随着冷却速度的提高,中碳非调质钢的沉淀强化和珠光体强化效果趋于增加。     

电力铁塔金具材料碳含量与组织和性能关系探讨

通过对一系列不同成分板式金具工件和5炉不同碳含量实验钢力学性能检测和微观组织分析,研究了碳含量对电力铁塔金具用Q235B钢组织和力学性能的影响。Q235B材料强化作用取决于多种强化方式叠加产生复合作用,随着碳含量增加,铁素体基体中固溶强化作用逐渐增强;第二相即珠光体体积分数增加,其起到的强化作用增强。分析得出:随着碳含量增加,Q235B钢组织中珠光体含量增加,强度升高,韧塑性降低。碳含量(质量分数)小于0.068%时组织中珠光体含量少,材料强度降低。出于金具服役安全性考虑,电力铁塔金具用Q235B钢中碳含量在标准范围内应保证不低于0.068%,保证材料足够的强度。     

高强韧性非调质钢F28MnSiVTiRE研发

中碳钢中加入V、Nb、Ti、Al、RE等细化晶粒元素,利用N、C与细化晶粒元素形成稳定的化合物来细化奥氏体晶粒,增加非调质钢的强度及韧性,采用金相显微镜和透射电镜观察,N、C与V、Nb、Ti、Al形成稳定化合物,成功研发出铁素体-珠光体型非调质钢,其屈服强度大于550 MPa,抗拉强度大于780 MPa,硬度(HB)不小于210,延伸率大于18%,面缩率大于45%,常温V型缺口冲击值大于50 J。与普通非调质钢相比,非调质钢F28MnSiVTiRE具有高强度、高韧性、易切削等优点,可用于加工汽车曲轴、发动机连杆等部件。     

终锻温度和变形量对贝氏体型非调质钢强韧性的影响

 用JB 30冲击试验机、MTS材料试验机和OM等试验方法分析了两种终锻温度（820 ℃和950 ℃）和三种变形量(3、4、6,锻造变形前后工件截面积的比值)条件下,贝氏体型非调质钢强韧性的变化及其微观组织的区别。研究结果表明：终锻温度和变形量对贝氏体型非调质钢强韧性的主要影响可以从铁素体含量、原始奥氏体晶粒和贝氏体束尺寸等因素来考虑。终锻温度降低、变形量增大、原始奥氏体晶粒尺寸减小导致贝氏体束尺寸减小,硬度、强度和冲击韧性增加;而当终锻温度为820 ℃和变形量为6时,由于变形诱导铁素体相变,铁素体体积分数达到10%,强度和硬度明显降低。     

铌钒微合金中碳钢的微观组织与强度的关系

介绍了工业试制铌钒微合金中碳钢的微观组织与强度的关系。在Ｇｌａｄｍａｎ中碳钢方程和实验结果的基础上，提出了屈服强度和抗拉强度的新方程。该方程与钢的成分、晶粒尺寸、铁素体体积百分数、珠光体片间距和析出物颗粒有关，理论计算的屈服强度和抗拉强度值与实验结果吻合。该方程不仅适合微合金中碳钢的铁素体和珠光体组织，而且也适合高碳微合金钢的珠光体组织和低碳微合金钢的铁素体组织。     

Influence of Vanadium on Fracture Splitting Property of Medium Carbon Steel

The fracture splitting property of medium carbon steel 37MnSiS microalloyed with V up to 0. 45% was investigated by using simulated fracture splitting test,for the development of new crackable medium carbon steel to manufacture high performance connecting rod. Conventional high carbon steel C70S6 was used for comparison. The results show that the volume fraction of both ferrite and V-rich M( C,N) particles increases,and the pearlite interlamellar spacing decreases with increasing V content,which in turn results in gradual increase of strength and decrease of ductility and impact energy. The fracture splitting property of the tested steel could be improved significantly due to the increase of V content mainly through the precipitation hardening mechanism of fine M( C,N) precipitates. The fraction of brittle cleavage fracture in the crack initiation area increases noticeably with increasing V content and full brittle cleavage fracture surface could be obtained when V content was increased to 0. 45%. It is concluded that medium carbon steel with V content higher than about 0. 28% possesses not only comparable or even higher mechanical properties with those of conventional steel C70S6,but also excellent fracture splitting property,and therefore,is more suitable to fabricate high performance fracture splitting connecting rod.     

Effects of Widmanstätten ferrite on the mechanical properties of a 0.2 pct C-0.7 pct Mn steel

Laboratory melted and rolled C-Mn steel plates were austenitized at either 925 °C or 1150 °C to produce nominal austenite grain sizes of 60 and 200 μm, resspectively. The plates were then cooled at rates in the range of about 2 °C/min to 400 °C/min to produce mixed polygonal ferrite/Widmanst?tten ferrite/pearlite microstructures. The percentage of Widmanst?tten structure (a Widmanst?tten ferrite/pearlite aggregate) increases with increasing prior austenite grain size and cooling rate. Both yield strength and impact toughness increase with decreasing austenite grain size and increasing cooling rate. This simultaneous improvement in strength and toughness is attributed to overall refinement of both the polygonal ferrite and Widmanst?tten structure. Both yield and tensile strength increase with an increase in the volume fraction of Widmanst?tten ferrite and a reduction in ferrite grain size. In contrast, the toughness level achieved in these polygonal ferrite/Widmanst?tten ferrite/pearlite microstructures depends largely on the ferrite grain size; the finer the grain size, the better the toughness.     

Effect of N content on microstructure and properties of Nb microalloyed HRB400E rebar

The purpose of this study is to better play the role of N in Nb microalloyed rebars, in order to reduce production costs and provide a theoretical basis for the design of rebars. Using metallographic microscope, scanning electron microscope, transmission electron microscope, and mechanical testing machine to carry out microstructure characterization and mechanical performance test of different N content of Nb microalloyed high strength seismic rebars, and explore the effect of N content on the structure and mechanics of Nb microalloyed high strength anti seismic rebars. The results show that the austenite structure during the rolling process decreases with the increase of N content; the final structure is ferrite and pearlite. As the N content increases, the average ferrite grain size and the interlamellar spacing decreases, but the continuity of lamellar pearlite increases. In Nb microalloyed high strength anti seismic rebars, the precipitated phase is Nb(C,N). With the increase of N content, the number of precipitated phase and the second particle volume fraction of precipitation increases, but the particle size decreases accordingly. In terms of mechanical properties, the yield strength gradually increases, and the tensile strength shows a phenomenon of increasing first and then decreasing.     

N含量对Nb微合金化HRB400E钢筋组织与性能的影响

摘要：为了更好地发挥N元素在Nb微合金化钢筋中的作用,降低生产成本以及为钢筋成分设计提供理论依据。利用金相显微镜、扫描电镜、透射电镜、力学试验机对不同N含量的Nb微合金化高强抗震钢筋进行显微组织表征及力学性能测试,探究N含量对Nb微合金化钢筋的组织与力学性能的影响。研究表明,轧制过程中的奥氏体组织,随着N含量的增加,平均奥氏体晶粒有所减小;最终组织为铁素体和珠光体,随着N含量的增加,铁素体平均晶粒尺寸而减小,片层状珠光体的连续性增加,片层间距减小;析出相Nb(C,N)随着N含量的增大,沉淀析出的第二项颗粒体积分数增大,颗粒尺寸随之减小;在力学性能方面,屈服强度逐渐增加,抗拉强度先增加后减少。     

高碳钢线材组织和屈服强度关系的数学模型

通过光学和扫描电子显微镜,运用定量金相技术,分析计算高碳钢(%:0.56～0.63C、0.60～0.71Mn、0.23～0.28Si)铁索体含量和珠光体片间距,建立高碳钢线材的组织和屈服强度(σ_s)之间关系的数学模型:σ_a(Pa)=104.52×10^-6+161.70(1-f_a^1/3)S^-1(m),其中fa~-铁素体的体积百分数,S-珠光体的片层间距。模型的计算值与实验值的相对误差为2.9%。     

Improvement in Mechanical Properties of Microalloyed Steel 30MSV6 by a Precipitation Hardening Process

 The microstructural evolutions and mechanical properties of vanadium microalloyed steel (30MSV6) during precipitation hardening were studied. The effects of aging temperature and cooling rate on mechanical strength (yield strength and ultimate tensile strength) were similar. Increasing aging temperature or cooling rate firstly increased the mechanical strength of specimens up to their maximum values, which then decreased with further increase in aging temperature or cooling rate. Microstructural evolutions revealed that cooling rate had significant effects on the pearlite interlamellar spacing and size of pre-eutectoid ferrite. Unlike the effect of austenitizing temperature, the pearlite interlamellar spacing and pre-eutectoid ferrite size were decreased by increasing the cooling rate from austenitizing temperature. According to the microstructural evolutions and mechanical properties, the optimal heat treatment process of microalloyed steel 30MSV6 was austenitizing at 950 ℃ for 1 h, air cooling (3. 8 ℃/s) and aging at 600 ℃ for 1. 5 h. This optimal heat treatment process resulted in a good combination of elongation and yield strength.     

核岛用P280GH碳锰钢热老化的组织和性能

 P280GH碳锰钢用于制造压水堆核电站核岛蒸汽系统和辅助系统管道,其在280～350 ℃的长时服役过程中易于出现老化现象。为了研究其热老化机理,在400 ℃温度下进行了P280GH碳锰钢的10 000 h的加速热老化试验。测定了不同老化时间下铁素体和珠光体的显微硬度、试样拉伸性能和冲击性能。结果表明,铁素体和珠光体的显微硬度随老化时间的增长而逐渐减小;老化时间少于300 h时,拉伸强度和屈服强度随老化时间增长而增加,老化时间大于300 h后,抗拉强度逐步降低,屈服强度缓慢降低;冲击吸收功随老化时间的增加而减小。上述力学性能变化与热老化过程中的珠光体形貌变化及铁素体中的位错移动有关。