热处理对高硼低碳铸钢显微组织和性能的影响

在含碳量小于0.2%的低碳铸钢中加入1.0%B,获得了高强度高硼耐磨铸钢,并研究了淬火温度对高硼铸钢显微组织和性能的影响.结果显示,在900～1 050℃内淬火,均可获得单一的马氏体组织,淬火温度的变化对硬度影响不明显.随着淬火温度提高,硼化物由连续网状分布变成断网状分布,导致冲击韧性提高;淬火温度超过1 000 ℃后,冲击韧性变化不明显.另外,在900～1 050 ℃内淬火,高硼铸钢均具有优良的耐磨性.     

钒对贝氏体球墨铸铁组织与硬度的影响

研究了钒在连续冷却淬火贝氏体球墨铸铁中的存在形式和作用,以及对球墨铸铁贝氏体组织和性能的影响机制.结果表明:钒在贝氏体球墨铸铁中以固溶和弥散碳化物2种形式存在,它能有效地增加贝氏体形核率,促进贝氏体转变,细化贝氏体组织,强化基体,提高硬度.因此,钒可替代钼、镍、硼等元素生产贝氏体球铁.     

渗硼温度对高钒耐磨钢渗硼层组织与性能的影响

通过固体粉末渗硼法对高钒耐磨钢表面进行渗硼实验,采用X射线衍射、扫描电镜、显微硬度计等检测手段研究了渗硼温度对渗硼层组织和性能的影响.结果表明,高钒耐磨钢经固体渗硼后,可得到一定厚度、组织致密的渗硼层.渗硼层的物相为FeB单相,并呈针齿状楔入基体,与基体结合牢固.渗硼温度由850 ℃升至1000 ℃时,渗硼层厚度由36...     

合金元素对奥氏体-贝氏体型球墨铸铁组织和性能的影响

根据不同的合金元素对球墨铸铁基体组织的影响，将锰、钼、镍和铜的含量合理搭配，以岩棉为冷却介质，在连续冷却过程中获得了性能较好的奥氏体-贝氏体型球墨铸铁，HRC可达33～48，αk可达26～48J／cm^2。     

大气层流等离子体扫描速度对球墨铸铁组织和性能的影响

采用自行研制的表面淬火层流等离子体系统,对QT450球墨铸铁进行表面淬火.用光学显微镜(OM)、显微硬度仪、X射线衍射仪(XRD)、扫描电镜(SEM)等,研究了淬火区的尺寸、组织结构和硬度.研究表明,淬火试样的表面组织为渗碳体、细小珠光体、马氏体和部分残留奥氏体等.试样从表向里主要由熔融区、热影响区和基体三部分组成.在...     

硼对点焊热影响区组织和疲劳强度的影响研究

研究了硼对IF钢DC06点焊热影响区组织和疲劳寿命的影响。加硼后,显微组织分析可知IF钢DC06的晶粒得到细化。对点焊热影响区进行能谱分析和电子探针扫描分析,发现热影响区内晶界上的微合金元素硼总体含量略高于晶内,说明硼主要在晶界偏析。试验结果表明:硼元素的加入抑制了热影响区晶粒的长大,强化了晶界,提高了IF钢DC06的疲劳强度。     

热处理对低合金耐磨钢K400组织性能的影响

针对低合金耐磨钢的性能要求,以日本住友金属生产的＂Sumihard-K400＂低合金耐磨钢为研究对象,研究了不同淬火温度和回火温度与组织性能的关系,得到硬度、冲击韧性的良好配合,以满足高强度耐磨钢的使用要求。研究结果表明：经淬火加低温回火后的板条马氏体组织与K400原始组织相近。当淬火温度从900℃上升到1 000℃时...     

喷射成形球墨铸铁的显微组织

采用喷射成形工艺研究了球墨铸铁的显微组织。结果表明,球化不良的铸铁和球墨铸铁经重熔喷射成形成了组织致密、石墨细小均匀分布的球墨铸铁,且晶粒均匀细小,无化学成分偏析。与砂铸和水平连铸的球墨铸铁组织相比,喷射成形的球墨铸铁组织得到大大改善。     

硼对780 MPa低碳贝氏体钢组织和力学性能的影响

试验低碳贝氏体钢（/%:0.08C,0.11~0.13Si,1.10~1.20Mn,0.008~0.009P,0.002S,0.21~0.23Ni,0.020~0.021Ti,0.003~0.004Nb,0~0.0010B,0.000 7~0.0008O,0.0031~0.0033N）由50kg真空感应炉熔炼,轧成45mm钢板,并经930℃淬火,610℃回火。研究了0.0010%硼对780 MPa低碳贝氏体钢45mm板组织和力学性能的影响。结果表明,硼可显著提高试验钢的淬透性,不含硼试验钢淬火后得到粒状贝氏体,0.0010%硼试验钢淬火后得到板条贝氏体。硼明显改善试验低碳贝氏体钢的力学性能,含0.0010%硼试验钢淬、回火后的抗拉强度834MPa和屈服强度771MPa远高于不含硼试验钢的抗拉强度702MPa和屈服强度591MPa,实际生产中应加入适量硼可使低碳贝氏体钢得到板条贝氏体。     

酸溶硼含量对低碳钢组织性能的影响

在特定条件下定量研究了酸溶硼含量对钢材力学性能的影响。通过对比研究发现,每提高1 ppm的酸溶硼含量可以提高22.05 MPa的抗拉强度,29.55 MPa的屈服强度。酸溶硼含量的提高有效提高了钢的各项性能,钢中固溶硼对提高钢的淬透性起到至关重要的作用,改善了钢的显微组织状态,提高了钢的强度和冲击韧性,并且减少了由于BN含量的增加造成的韧性下降。     

Microstructure, Impact Fatigue Resistance and Impact Wear Resistance of Wear Resistant Low Cr-Si Cast Iron

Wear parts are greatly consumed in metallurgi-cal industry,fire power stations and cement works.The consumption of grinding balls and lining platesmay be the greatestunder such impactabrasive wearconditions.In China,annual consumption of ballsand plates is close to 1× 10 6 t.Therefore,develop-ing a new material for impact wear conditions is veryimportant.　　 The martensitic high chromium cast iron(WCr= 15 % ) is widely studied and used as wear resis-tance material[1— 8] ,especially for ma…     

Microstructure and Mechanical Properties of Ductile Cast Iron in Lost Foam Casting with Vibration

The microstructures and mechanical properties of the ductile cast iron （DI） specimens obtained by lost foam casting （LFC） with and without vibration were investigated. The results indicate that the number of the graphite nodule increases from 175 mm 2 of the specimens produced by LFC without vibration to 334 mm^-2 of the specimens produced by LFC with vibration, and the thickness of the ferrite shell increases. Meanwhile, the amount of the carbides decreases in the specimens produced by LFC with vibration and the granule structure then forms. These are mainly attributed to the ＂crystal shower＂ caused by the vibration. In addition, the tensile strength and elongation of DI specimens produced by LFC with vibration are improved due to the dispersion-strengthening of refined carbide and Dearlite colonv, uniform distribution of the graphite nodule, and increase of the amount of dimples and tearing edges.     

Effect of Microstructure on Impact Fatigue Resistance and Impact Wear Resistance of Medium Cr-Si Cast Iron

 A great amount of iron grinding balls in tube mills have been consumed. Under this impact abrasive wear working condition, the failure of wear resistant alloying white irons grinding balls is mainly caused by fatigue spalling. The impact wear resistance of martensitic high chromium cast iron (Cr of 15%) is not high sometimes, but its cost is not low. Thus, medium Cr Si wear resistant cast iron is recommended. The influence of the iron on impact fatigue resistance and impact wear resistance is pronounced. Ball on ball impact fatigue test and high stress impact wear test of the grinding balls have been carried out. The results show that the impact fatigue resistance (IFR) and impact wear resistance (IWR) of medium Cr Si cast iron are superior to those of martensitic high chromium cast iron (Cr of 15%). The main reasons are that (1) the stress in medium Cr Si cast iron is released in the as cast state; (2) the matrix is fine pearlite with better toughness and plasticity; (3) the pearlite is more stable compared with a retained austenite under repeated impact load and less phase transformation can take place; (4) high silicon content improves the morphology of eutectic carbide; (5) there is no secondary carbide which results in less crack sources. All these factors are beneficial to improvement of impact fatigue spalling resistance. The eutectic carbide M7C3 is the main constituent to resist wear.     

Effect of Microstructure on Impact Wear Resistance Impact Fatigue Resistance and of Medium Cr-Si Cast Iron

A great amount of iron grinding balls in tube mills have been consumed. Under this impact abrasive wear working condition, the failure of wear resistant alloying white irons grinding balls is mainly caused by fatigue spalling. The impact wear resistance of martensitic high chromium cast iron （Cr of 15%） is not high sometimes, but its cost is not low. Thus, medium Cr-Si wear resistant cast iron is recommended. The influence of the iron on impact fatigue resistance and impact wear resistance is pronounced. Ball-on-ball impact fatigue test and high stress impact wear test of the grinding balls have been carried out. The results show that the impact fatigue resistance （IFR） and impact wear resistance （IWR） of medium Cr-Si cast iron are superior to those of martensitic high chromium cast iron （Cr of 15%）. The main reasons are that （1） the stress in medium Cr-Si cast iron is released in the as-cast state; （2） the matrix is fine pearlite with better toughness and plasticity; （3） the pearlite is more stable compared with a retained austenite under repeated impact load and less phase transformation can take place; （4） high silicon content im- proves the morphology of eutectic carbide; （5） there is no seeondary carbide which results in less crack sources. All these factors are beneficial to improvement of impact fatigue spalling resistance. The eutectic carbide M7C3 is the main constituent to resist wear.     

铸态高韧性球墨铸铁的研制和应用

对铸态直接获得高韧性球铁进行了研究。试验表明,在保证石墨球化良好的情况下,硅、锰含量是影响铁素体量和延伸率δ%的主要因素,δ%值随着硅的增加和锰的降低而相应地提高,在Si(2.90~3.20)%、Mn(0.15~0.40)%范围内,δ%值可达(19~21)%。这种铸态高韧性球铁成功地用于生产厚大断面和薄壁铸件。     

稀土硅铁合金对硼铸铁性能的影响

本文研究了稀土硅铁合金不同加入量对硼铸铁机械性能和耐蚀性的影响。结果表明，当加入量为０．４％时，σｂ＝２８４ＭＰａ，ＨＢ＝２２０，耐（酸）腐蚀性能最好。而且随温度升高，稀土硼铸铁耐（酸）腐蚀速度增大，随介质中ｐＨ值减小，耐（酸）腐蚀速度也增大。     

Effect of Boron and Heat Treatment on Mechanical Properties of White Cast Iron for Mining Application

 Heat treatment methods were applied to white cast iron for improving the impact and wear resistance. Additionally, chemical composition optimization was made. Furthermore, the effect of boron addition on such applications was investigated. Samples were investigated by using optical and electron microscope methods. Hardness, wear and impact tests were conducted. The results showed that the secondary carbides in the standard alloy were iron-enriched, needle-like carbides M3C when the boron-added alloy contained Fe23(C,B)6 type, globular secondary carbides. It was concluded that heat treatment B provided higher wear and hardness properties, compared to the standard heat treatment. Optimum mechanical properties were obtained by lower destabilisation temperatures and increasing temperature reduced the wear resistance and hardness.     

Nucleation of Bainite in Bainite Ductile Cast Iron

The bainite ductile cast iron with given comppasition was quenched to get bainite strueture. The nucleating position of bainite and the distrihution of alloying elements in the matrix were measured. The results show thai the bainite nucleates at the interface between graphite and austenite during quenching. Based on the experimental results and thermodynamics, the nucleating tnechanism of bainite in ductile iron was analyzed.     

QT400-18L球墨铸铁的低温冲击断裂行为

在室温和低温下对QT400-18L球墨铸铁件进行Charpy冲击试验,采用金相显微镜、扫描电镜对冲击断口形貌进行分析,利用透射电镜对断口附近位错密度进行观察分析,探讨了球墨铸铁低温冲击断裂的机制。结果表明:温度对冲击韧性影响较大,随试验温度的降低,冲击吸收的能量显著减小。观察发现,低温冲击断口表现出两种不同的解理断裂刻面:"连续型"和"不连续型"河流形貌。球墨铸铁中裂纹优先在石墨与铁素体基体界面形成,其次在碳化物与基体界面形成。在低温冲击载荷作用下,活动位错源数量少,发生解理断裂。