Research of DP600 high strength steel wheels

Steel has been used as a traditional wheel materials for a long time.Before 1980' s,over 90% wheels were made of steels.Then,the yield strength of wheel steels increased gradually from 240 -350 MPa to 600 MPa or higher.The advanced high strength steels become the main wheel materials.Since 1990's,DP600 has been broadly applied in steel wheels oversea.However,there was little research of application of high strength steel wheels(especially wheel disc) in domestic wheel industrial.In presence, DP600 steel wheel is only developed in FAWSH by using imported CKD.Other domestic steel wheel manufacturers did little work on high strength DP600 wheel discs.Baosteel wheels Co.Ltd.is the first domestic company producing DP600 steel discs and has become the leading company in production of high strength wheel.Because of the high strength of DP600,its formability,springback,and wrinkle have become the keys of the successful application of DP600 steel.In this paper,the metallurgical and mechanical properties are firstly introduced and formation problems of DP600 are described compared to traditional steels.Secondly,FLD analysis has been done.Wrinkle and more springback are recognized.To solve these problems,an optimized solution is designed and the good result is obtained.The test has shown that the fatigue property of steel wheel discs made by DP600 have been greatly improved.

Test study on the fatigue performance of HSS for steel wheels

High-strength steel is currently one of the main material choices for creating lightw eight automobiles. To realize lighter wheels that can comply with harsh fatigue requirements,sufficient know ledge of the relevant material fatigue properties is required. Fatigue tests were conducted on Baosteel＇s 600 M Pa level dual-phase steel DP600,which is a typical high-strength hot-rolled steel for steel wheel,and on 550 M Pa level HR60. Whler（ S-N） fatigue curves were obtained for both steels,and the measured stress fatigue limits were 414 and 329 M Pa for the HR60 and the DP600,respectively.

Microstructure and mechanical properties of railway wheels manufactured with low-medium carbon Si-Mn-Mo-V steel

The suitability of carbide-free bainite steel as railway wheel materials was investigated. The low-medium carbon Si-Mn- Mo-V steel was designed to make railway wheels by forging and rolling. The slack quenching with water was conducted on the tread of rim section by programmed control to simulate isothermal heat treatment after being austenitized. Microstructures and mechanical properties have been studied. The results indicate that the microstructure of the rim is mainly carbide-free bainite, and the mixed microstructure of bainitic ferrite and granular bainite is observed in web and hub. The mechanical properties are superior to both the standard requirements and the commercial production, such as CL60 plain carbon. The Charpy impact energy is relatively high at room and/or subzero temperatures. The force-displacement curves and fractographies reveal the excellent ability of resistance to crack initiation and propagation.

Investigation of the Relation between Rolling Contact Fatigue Property and Microstructure on the Surface Layer of D2 Wheel Steel

Through the rolling contact fatigue experiment under the condition of the lubricating oil, this article investigated the relation between contact fatigue property and microstructure on the surface layer of D2 wheel steel. The results showed that although the roughness of the original specimen induced by mechanical processing would diminish to some extent in the experiment, the 0.5 - 1.5 μm thick layer of ultrafine microstructure on the original mechanically-processed specimen surface would still become micro-cracks and small spalling pits due to spalling, and would further evolve into fatigue crack source. Additionally, even under the impact of the load that was not adequate to make the material reach fatigue limit, the ferrite in the microstructure underwent plastic deformation, which led the refinement of proeutectoid ferrite grains. During the experiment, the hardening and the refinement caused by plastic deformation consisted with the theory that dislocation gave rise to plastic deformation and grain refinement. The distribution laws of hardness and ferrite grain sizes measured could be explained by the distribution law of the shearing stress in the subsurface.

Effect of Sliding Wear on Surface Microstructure and Wear Property of D2 Wheel Steel

In this paper, the surface microstructure and wear property of D2 wheel steel under sliding wear condition were studied by MRH-30 sliding wear tester. After testing, a transmission electron microscope (TEM), scanning electron microscope (SEM) with electron backscatter diffraction (EBSD), and micro-hardness testers were used to characterize the surface microstructure of samples with different cycles. The results show that the wear losss samples are increased as the increase of cycles, and the wear loss of wheel samples is higher than that of rail samples. The surface hardness and thickness of deformation layer of wheel samples are increased as the cycles increase. After sliding wear, the samples surfaces form the white etching layer with the thickness of several microns. Through the analysis of surface microstructure of sample with 12,000 cycles, the lamellar cementite in pearlite is fragment into cementite particles with the decrease of depth from surface, and the cementite is dissolved at surface to lead to the form of white etching layer. The ferrite grains are refined gradually and the fraction of high angle grain boundary is increased with the decrease of depth from surface. The nanosgrains layer of ferrite grains with 5 μm thickness is formed. According to the result of finite element simulation of contact surface temperature, the formation of surface nanograins and the dissolution of cementite are caused by the severe plastic deformation. The fiber structure of samples is formed after sliding wear, with direction of .

高强韧性轮辋用490CL车轮钢焊接开裂失效分析

采用闪光对焊制成的490CL车轮钢轮辋在扩口成型工序,从焊缝处开裂失效。通过宏观、微观断口形貌观察,化学成分和力学性能检测,显微组织检验,显微硬度测试及能谱成分分析,对高强韧性轮辋用490CL车轮钢焊接开裂原因进行分析。结果表明,焊缝开裂处存在一定面积的以氧化锰为主的焊接“灰斑”,降低了焊缝塑性,导致焊接好的轮辋在扩口成型时从焊缝融合线处开裂。从降低闪光留量、增加顶锻压强等方面调整焊接工艺参数,改善轮辋用490CL车轮钢焊缝质量,轮辋成型时焊缝开裂比率从1.5%降低至0.3%。

添加不同固体润滑剂铁基合金激光熔覆涂层的干滑动摩擦磨损性能

采用激光熔覆技术在CL60车轮钢表面分别制备不同含量WS_(2)(质量分数0~8.0%)和CaF_(2)(质量分数5.0%)固体润滑剂以及不同含量h-BN(质量分数0~2.0%)和CaF_(2)(质量分数0~2.0%)固体润滑剂的铁基合金涂层,对比研究了添加不同固体润滑剂铁基合金涂层的显微组织以及干滑动摩擦磨损行为和磨损机制。结果表明:所有涂层均主要由树枝晶和共晶组织组成,表面硬度均达到约800 HV,约为CL60钢的2倍。随着WS_(2)含量的增加,WS_(2)+CaF_(2)/铁基合金涂层的摩擦因数降低,磨损质量损失先降低后基本稳定,当WS_(2)质量分数为6.0%时,磨损质量损失最低,与未添加固体润滑剂的铁基合金涂层相比降低了26.7%,此时孔隙最少,磨损表面损伤轻微,磨损机制为磨粒磨损。随着h-BN含量的增加以及CaF_(2)含量的降低,h-BN+CaF_(2)/铁基合金涂层的摩擦因数与磨损质量损失均先降后增,且当CaF_(2)和h-BN的质量分数均为1.0%时,稳定摩擦因数与磨损质量损失均最小,与未添加固体润滑剂的铁基合金涂层相比,分别降低了32.7%和33.3%,此时晶粒最细小,组织最为致密,磨损表面以细小磨痕为主,磨损机制为轻微的磨粒磨损。

CL65车轮钢滚动疲劳磨损研究

利用双盘滚动磨损实验机对CL65车轮钢与U75V钢轨钢进行滚动磨损实验,研究CL65车轮钢表面出现的疲劳磨损现象。实验表明:CL65车轮钢的磨损情况由黏着磨损不断向疲劳磨损过渡。机加工表面细晶层主要出现在磨损的初始阶段,疲劳磨损裂纹的形成和扩展出现在细晶层内或细晶层与基体的界面,导致了细晶层的早期疲劳剥离。随着磨损周次的不断增加,原始片状珠光体和先共析铁素体,基体区域表层的塑性变形不断加剧,当塑性应变过大时,疲劳裂纹开始萌生,并逐渐开始向先共析铁素体区域、渗碳体与共析铁素体界面扩展。

车轮钢ER8在中性NaCl溶液中的电化学腐蚀行为

为研究ER8车轮钢在沿海中性氯盐环境下的腐蚀行为,通过电化学测试、腐蚀失重试验,结合扫描电镜(SEM)、X射线衍射(XRD)技术对ER8车轮钢在3种不同浓度中性NaCl溶液中的电化学腐蚀行为进行分析。极化曲线结果表明浸泡初期5.0%NaCl浓度下自腐蚀电流密度(Jcorr)最大,576 h后Jcorr在2.0%、3.5%NaCl浓度下均持续增大,腐蚀速率在2160 h时均大于0.12 mm/a。SEM结果显示腐蚀产物形貌主要为片状与团簇状结构,初期腐蚀产物形貌具有较多孔隙,难以阻碍Cl-与基体发生反应,2160 h时腐蚀产物结构更为均匀致密。XRD结果表明腐蚀产物主要由γ-FeOOH、α-FeOOH与Fe3O4组成。

38CrMoAl渗氮钢微晶刚玉砂轮摆线磨削工艺试验研究

在实际磨削38CrMoAl渗氮钢过程中,存在磨削烧伤情况。本文分别采用白刚玉砂轮和微晶刚玉砂轮磨削38CrMoAl渗氮钢,对比研究了不同磨料类型刚玉砂轮对磨削力和表面粗糙度的影响规律。试验结果表明:相较于白刚玉砂轮,微晶刚玉砂轮磨削时磨削力降低了14.2%。基于正交试验方法,通过微晶刚玉砂轮平面磨削试验,探究了磨削工艺参数对磨削力和工件表面粗糙度的影响。结果分析表明:磨削深度对磨削力影响最大,其次是工件进给速度和砂轮转速;对于工件表面粗糙度而言,工件进给速度的影响最大,其次是砂轮速度和磨削深度。最终采用微晶刚玉砂轮对38CrMoAl渗氮钢齿轮样件进行批次加工,结果显示无磨削烧伤发生,且磨削表面质量得到了显著提高。

微晶陶瓷磨料砂轮磨削轴承钢实验探讨

特定的生产或试验条件下不同的磨料制作的砂轮具有不同的性能表现,为了考察市售微晶陶瓷磨料(CA)的适用性,选取四种不同品牌相近规格的CA磨料制作新型CA磨料砂轮进行磨削试验,以等效组分等量替代法采用相同的砂结比、成型、干燥等工艺技术条件,制成砂轮样品并分别编号为1^(#)~4^(#),对轴承钢工件进行磨削试验,比对磨削比、磨削功率的变化以及磨削后工件表面质量、砂轮表面形貌特征,了解该工艺技术条件下不同CA磨料制得的低温陶瓷结合剂砂轮的性能.结果表明,1^(#)和2^(#)磨料制作的砂轮综合磨削性能较好,4^(#)无明显优势,但磨削后工件表面光洁度较好,3^(#)砂轮表现不佳.

环氧砂浆的三种非过流面耐磨性测试方法适用性分析

阐述了现有的非过流面耐磨性测试方法对环氧砂浆不适用的原因。通过调整三种测试方法的参数,绘制相应的磨损量-磨损时间(转数)曲线图,结合机械磨损理论的磨损过程图,分析三种非过流面耐磨性测试方法对环氧砂浆的适用性。最后,对三种非过流面耐磨性测试方法做出调整并进行适用性评价。

一种低碳排放钢铝复合轮毂连接方法研究

主要介绍钢制轮辋和铝合金铸造轮辐进行创造性连接的方法,达到既降低轮辋制造环节碳排放量,又不失铸造铝合金轮辐造型多样、美观属性的目的。对样轮进行可靠性试验,结果表明,该复合轮毂可靠性合格;相比传统同尺寸的铝合金轮毂,碳排放量降低超过52%,金属利用率增加14%;全序加工整体时间效率提升39%,并且具有进一步轻量化的潜力和铝轮毂外观多样性的优点。

UHPC提升钢桥面板纵肋-横隔板连接疲劳性能研究

文章采用有限元方法分析了钢桥面板纵肋-横隔板连接四个典型构造细节在有无UHPC铺装情况下的轮载应力响应,并对比UHPC铺装层对其疲劳性能的提升效果。研究结果表明,在无刚性铺装情况下,构造细节H、HD、LS和LZ的最不利应力分别为-82.1 MPa、28.3 MPa、43.3 MPa和-42.9 MPa;在采用50 mm厚UHPC铺装后,构造细节H、HD、LS和LZ的最不利应力分别下降为-45.6 MPa、13.0 MPa、14.7 MPa和-12.0 MPa;UHPC铺装层对钢桥面板纵肋-横隔板连接各构造细节的疲劳性能提升明显,其中构造细节LZ的疲劳寿命提升高达45.4倍。

引起电梯曳引钢丝绳与曳引轮失效的原因解析

随着我国经济社会的不断发展,城市化进程的不断加快,城市中高层、超高层建筑项目日益增多,规模越来越大,电梯作为高层建筑中缺一不可的交通运输设备,在人们的日常生活和工作中发挥了重要作用,因此,在电梯使用过程中应保证电梯的安全运行性能,规避电梯安全事故风险。

城市轨道交通公轨合建钢箱梁桥辐射噪声的影响规律研究

列车经过钢箱梁桥时引起噪声辐射问题相比混凝土桥更为突出,对沿线居民造成的影响更大,严重影响沿线居民的日常生活。基于车辆-轨道-桥梁耦合振动理论,并结合统计能量法(SEA)建立钢箱梁结构噪声与轮轨噪声预测模型,分析钢箱梁桥的结构噪声与轮轨噪声衰减规律,明确典型及敏感场点处的噪声分布情况;定量预测分析不同轨道减振措施对钢箱梁桥周边敏感场点的噪声辐射大小。分析结果表明:钢箱梁轮轨噪声与结构噪声随水平距离的衰减规律基本一致,衰减率均为随着距离变远而变小,150 m内总衰减率轮轨噪声大于结构噪声;普通轨道结构及普通轨道结构+全封闭声屏障工况下,敏感位置处综合噪声不满足噪声增量在1 dB(A)以内的环评要求,减振垫浮置板与全封闭声屏障组合及钢弹簧浮置板与全封闭声屏障组合工况下,敏感位置综合噪声均能满足噪声增量在1 dB(A)以内的环评要求。

轮迹线位置对钢桥面板横隔板交叉细节疲劳应力影响分析

正交异性钢桥面板疲劳性能较差,构造细节易发生疲劳开裂,其中横隔板交叉细节的疲劳损伤最为突出。为研究车辆轮迹线位置对横隔板交叉细节疲劳性能的影响,分别以围焊和开孔部位为研究对象,计算得到典型横向轮迹线位置下的疲劳应力历程曲线。结果表明:围焊和开孔部位的疲劳应力幅均在轮迹线处于纵肋腹板正上方典型工况时达到最大值,分别为67.4MPa和109.7MPa,其中开孔部位疲劳应力峰值较大,应加强该部位的优化设计和加工质量控制。

非同心双轴轮辐状空间钢结构施工技术——以佛山市某新建实验项目钢结构茶室为例

钢结构施工技术作为一种现代化的建筑技术,以强度高、自重轻、施工速度快等优点,在建筑施工中得到了广泛应用。钢结构由上下两个轮辐状圆环组成,每个轮辐状圆环由三个圆形钢梁与辐条构成,其圆心不在同一轴线,轮辐状圆环由多角度双肢支柱支承。工程外形复杂,平面曲线化,各单件构件形状尺寸不统一,构件之间拼装接口的不一致性等问题加大了施工的难度。本文将依托该工程提出研究“非同心双轴轮辐状空间钢结构施工技术”的课题,对于该建筑类型钢结构具有重要意义。

斗轮堆取料机回转钢结构强度及疲劳计算

通过计算某型斗轮堆取料机回转钢结构的静强度和疲劳强度,评定结构强度的富裕度。根据载荷对结构的影响将结构受载分为4种工况,分别为水平重载工况、上仰空载、下俯空载和下俯重载,并采用有限元法对结构展开静强度计算。根据斗轮堆取料机工作循环的载荷历程,结合钢结构的设计工作寿命,建立回转钢结构的循环载荷谱,按Miner线性累计损伤准则进行疲劳强度计算。计算结果表明:4种工况下结构整体应力偏低,但是局部应力较高;回转钢结构的疲劳计算结果为0.97,疲劳强度富裕度也较低,可以优化结构局部高应力区,以降低结构局部高应力。

钢桥面板顶板-U肋焊缝裂纹萌生特征及扩展规律

【目的】研究轮载作用下钢桥面板顶板-U肋焊缝裂纹的萌生特征及扩展规律。【方法】通过有限元方法建立钢桥面板节段模型,分析了不同轮载位置下构造的变形特征,明确了轮载位置与典型变形特征的对应关系,相应建立了3种局部简化模型。在局部模型的基础上根据应力分布确定了裂纹萌生特征,并基于断裂力学进行裂纹扩展三维数值模拟。【结果】模拟结果表明,在以顶板为主的变形条件下,顶板焊趾和顶板焊根的最大主应力明显大于U肋焊趾处,裂纹产生后Ⅰ型应力强度因子远高于Ⅱ型和Ⅲ型;在以U肋为主的变形条件下,顶板焊根和U肋焊趾处的最大主应力垂直于U肋厚度方向,裂纹产生后Ⅱ型和Ⅲ型应力强度因子占Ⅰ型应力强度因子K的20%~30%。【结论】实桥中轮载偏离焊缝正上方时,疲劳裂纹易从顶板焊根和顶板焊趾处萌生且沿顶板厚度方向扩展,以Ⅰ型裂纹为主;当轮载位于焊缝正上方时,疲劳裂纹易从顶板焊根和U裂焊趾处萌生并大致垂直U肋腹板扩展,属于Ⅰ-Ⅱ-Ⅲ复合型裂纹,且扩展速率较快。