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通过金相、X射线衍射、透射电子显微镜和硬度测定,对TiC钢结硬质合金进行显微组织、物相和硬度分析。结果表明:钢结硬质合金由颗粒状的硬质相TiC和奥氏体组成,硬质相TiC表层包覆Mo2C,硬质相TiC的存在给周围基体带来一定的应变,并造成大量位错缠结,基体本身的位错密度较高,增加塑性变形时对位错滑移的阻力,提高了合金的强度。 相似文献
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海洋环境对于金属的腐蚀具有明显的加速作用,尤其在高铁海底隧道环境中,金属比正常的服役时间变短,这种腐蚀情况下会影响高铁的安全和准点运行。基于以上背景,通过夹杂物自动扫描、钢的加速腐蚀及电化学测试对钢中的夹杂物诱发腐蚀行为进行系统分析,重点分析了高铁轨旁信号设备连接金属件(Q235)中夹杂物在盐雾环境下的腐蚀行为。结果表明:钢中主要夹杂物为氧化物、硫化物或者其复合夹杂,而这两类夹杂物对于诱发钢基体点蚀的原因不同。其中数量最多、尺寸小于5 μm类型的夹杂物为硫化物夹杂和氧硫复合类型夹杂物;数量少、尺寸大于5 μm的夹杂物为氧化物夹杂。在服役过程中,钢中硫化物夹杂易溶解脱落形成点蚀坑,而氧化物夹杂周围基体会先溶解引起夹杂物脱落形成点蚀坑,复合类夹杂物也是诱发钢发生腐蚀的因素,不同复合类型的夹杂物腐蚀方式不同,硫化物夹杂和氧硫复合夹杂对碳钢影响较大。电化学测试表明自腐蚀电位约为为−0.1 V,Q235钢本身抗腐蚀能力不强。夹杂物在腐蚀过程中参与了腐蚀,引起阳极极化曲线的波动,加快了Q235钢的腐蚀情况。研究结果对于认识和改善钢的耐腐蚀性能有指导意义。 相似文献
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在用户使用Q235B棒材过程中,出现了不同的加工质量问题。采用金相显微镜对金相组织和夹杂物进行分析,并检测了试样的化学成分。结果表明,产生加工质量问题的原因主要是目前生产的钢中B类夹杂物超标、P元素含量波动范围大并超出要求上限、连铸过程中脱方等现象。对此提出了相应的控制措施,为提高产品质量提供了指导。 相似文献
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在304不锈钢表面采用半导体激光熔覆制备Ni包B_4C涂层,研究激光加工参数对涂层的组织形貌、物相组成、硬度和耐磨性能的影响。结果表明,当激光功率为3 k W和扫描速度为6 mm/s时,熔覆层无气孔、无裂纹,与基体呈冶金结合;熔覆层的显微组织为枝晶共熔体和再生的二次枝晶,熔覆层的主要物相由γ-Ni,Ni_4B_3,Fe_3C,B_4C,B_(13)C_2,Cr_3Ni_2,(Fe,Ni)23C6和Fe_(23)(C,B)_6等组成;熔覆层具有较高的硬度(平均值为900 HV_(0.2)),耐磨性是基体的7.6倍,硬度和耐磨性的提高归因于熔覆层中未完全熔解的B_4C颗粒以及新形成的强化相和硬质相。 相似文献
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本文采用真空反应烧结合成出Mo2FeB2硬质颗粒,并采用感应熔覆技术在钢基体表面成功制备出以Mo2FeB2为强化相的硬质涂层,并对其组织结构、界面相容性和耐磨性进行了研究。结果表明,在1 350℃真空烧结30min所制得Mo2FeB2硬质相颗粒分布均匀致密且硬度高;感应熔覆Mo2FeB2/Fe涂层的硬质相最佳含量为50%质量分数,涂层组织分布均匀孔洞较少,硬度高达65.5HRC,涂层与基体结合良好。磨损试验表明,Mo2FeB2强化层具有比YG8硬质合金更好的耐磨性。 相似文献
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为提高钢基硬质涂层的表面质量和显微硬度,采用真空消失模铸造法引发自蔓延高温合成(SHS)反应,在铸件表面制备原位合成TiC颗粒增强钢基硬质涂层。通过X-ray、OM、SEM、EDS及显微硬度测试等方法,研究了稀释剂TiC的加入量对钢基硬质涂层微观组织和力学性能的影响。结果表明:硬质涂层与基材之间呈冶金结合,涂层组织由TiC颗粒和α-Fe基体相构成;随外加TiC含量的增加,可降低燃烧反应温度,提高涂层组织致密度,原位合成的TiC颗粒细小呈圆球或近圆球形状,均匀分布在基体组织中,显著提高了TiC颗粒总体积分数和硬质涂层显微硬度,其中TiC加入量为10%(质量分数)时,涂层的综合性能最佳。 相似文献
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《稀有金属》2015,(5)
采用激光熔覆技术,在20Cr基体上熔覆了硬度较高的Ni60+35WC-Ni耐磨涂层,并与Ni60涂层进行比较。采用扫描电子显微镜(SEM)、能谱分析仪(EDS)和X射线衍射分析仪(XRD)对涂层的微观组织、元素成分和物相进行了表征分析,测试了涂层沿深度方向上的显微硬度,在20和300℃条件下进行了点接触干滑动摩擦磨损试验,并利用SEM和EDS对磨损表面进行微观组织和元素成分分析。结果表明:Ni60+35WC-Ni涂层所含物相主要包括Fe-Ni,Cr7C3和WC,硬质相WC和Cr7C3有利于提高涂层的硬度和耐磨性。Ni60+35WC-Ni涂层的平均显微硬度约为基体平均硬度的3倍。与Ni60涂层相比,Ni60+35WC-Ni涂层的平均硬度较高,且其中含有硬质相WC,磨损量较小。在相同温度条件下,Ni60+35WC-Ni和Ni60两种涂层的摩擦系数相差不大。对于同一涂层而言,300℃时涂层的摩擦系数明显低于20℃下的摩擦系数,但磨损量随温度增加而增加。 相似文献
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The general purpose of this work is a thermodynamic study of non‐metallic inclusions in the CC tundish for SAE 8620 steel. Specific purposes are: (1) Obtaining the phases formed and their composition in inclusions by applying computational thermodynamics for SAE 8620 steel; (2) Establishing conditions of steel composition for the improvement of SAE 8620 castability, including the plant validation in terms of the castability index. Thermodynamic studies were performed with the commercial software FactSage and databases. Simulations were carried out by the global chemical composition of SAE 8620 steel in the CC tundish, resulting in both steel composition and non‐metallic inclusions (oxides and sulphides) at the desired temperature. Furthermore, results showed both different solid oxides and liquid phase formation in inclusions by varying calcium content in the steel. Thus, it was possible to determine the inclusion composition as a function of aluminium and calcium content of SAE 8620 steel, and moreover, to establish a range of calcium content in which the inclusions are predominantly formed by liquid phase. In addition, the percentages of liquid and solid phase in inclusions, as well as, oxide compositions could be calculated. 相似文献
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高碳含铜孪生诱发塑性(TWIP)钢的纯净化制备对充分发挥其优异性能具有重要性。为了提高高碳含铜TWIP钢的洁净度, 实验利用金相显微镜、扫描电镜及能谱仪等对该TWIP钢经真空感应熔炼、固溶处理后的铸锭和热轧板材中非金属夹杂物进行分析, 找出了钢中夹杂物类型、来源以及不同工序的变化规律。结果表明, TWIP钢中主要存在铁锰氧化物、硅酸盐类夹杂、硫化物和氮化物。在该TWIP钢使用和热加工的温度范围内, 硫化物表现出良好的塑性, 氮化物属硬质脆性夹杂物。硅酸盐类夹杂物和铁锰氧化物变形特性受其成分和温度变化的影响较为明显。 相似文献
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���£�֣��ѧ�ã����ǿ������ 《钢铁研究学报》2017,29(12):973-981
The characteristics of inclusions in high strength structural steel were characterized by scanning electron microscopy and energy dispersive spectroscopy. The influence of Ti- alloying and Ca treatment on the composition of inclusions in the steel was investigated, and the effect of oxides on the precipitation behavior of TiN and its refining effect on the microstructure were studied. The results show that the inclusions in the steels are Al- Ti- Mg- O system with spherical or polygonal shape after adding Ti, which furtherly can be effectively modified into spherical inclusions after adding Ca. The TiOx in inclusions can be reduced by Ca treatment and Ti gradually diffuses into the surface of the inclusions, which promotes the local precipitation of TiN on the surface of the composite oxides. The amounts of fine oxides and nitrides in steel increase with the increase of Ti mass percentage. Therefore, Ca treatment and higher Ti content can promote the formation of the inclusions of composite oxide and TiN, and also delay the homogeneous nucleation time of TiN inclusions, reducing its size during solidification process of the steel. TiN with the size about 2-3??m not only can induce polygonal ferrite, but also induce acicular ferrite. Specially, the inclusions with TiN and MnS locally precipitating on the surface of composite oxides are conducive to the nucleation of interlocking acicular ferrites. 相似文献
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对管线钢铸坯中的硫化物特征进行了分析,并对其形成机理进行了讨论。发现从中间包钢液到铸坯,管线钢中夹杂物由低熔点的CaO Al2O3向CaS Al2O3类型转变,且夹杂物尺寸越小,在冷却过程中的转变越充分。根据形貌特征,含硫化物夹杂可分为以下几类,即硫化物在氧化物表面部分析出、硫化物半包裹氧化物、硫化物完全包裹氧化物、纯硫化物和在TiN上析出的硫化物。采用FactSage软件对冷却过程管线钢中的夹杂物转变进行了计算,发现随着温度的降低,液态钙铝酸盐夹杂物逐渐经历CaO·Al2O3→CaO·2Al2O3→CaO·6Al2O3→Al2O3的转变过程,同时CaS和MnS相也在冷却过程中析出,且MnS的析出温度低于CaS,这解释了铸坯中硫化物的特征和形成。 相似文献
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针对淮钢弹簧钢60Si2CrVAT,采用金相、SEM-EDS等分析方法,研究了精炼过程中夹杂物尺寸、成分、形貌等变化的情况,结果表明,在LF炉精炼后,微观夹杂物由30.57个/mm2下降到8.93个/mm2,减少了70.79%,RH循环脱气处理后,夹杂物略有减少,经轧制后,夹杂物数量有所增加。随着冶炼过程的进行,大颗粒夹杂得到有效去除,细微夹杂物所占比例逐步升高。钢中存在的夹杂物主要有氧化物、硫化物,以及CaO(CaS)-Al2O3-SiO2类复合夹杂物,成材中以复合氧化物为主。 相似文献
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通过取样检测结合热力学计算,分析了钙处理对成品无取向硅钢中夹杂物特征及硫化物夹杂的析出机制的影响。结果表明,钢中尺寸大于3μm的有害夹杂物主要是AlN、MgO-SiO2、CaO-Al2O3-SiO2类复合夹杂物及其与MgS、MnS、CaS的复合析出物。钙处理钢中没有检测到单独的Al2O3、SiO2及铝酸钙类夹杂物。钙处理钢中形成的液态3CaO·Al2O3、MgO·SiO2和Al2O3夹杂物被精炼渣吸收,改性去除了钢中大尺寸Al2O3夹杂物。钙处理钢中尺寸大于3μm的氧化物夹杂主要是含CaO和(或)CaS的Al2O3-SiO2类夹杂。硫化物在MgO-SiO2类氧化物表面的析出有利于其形貌趋于规则。钢... 相似文献
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PC钢棒在生产过程中出现镦头开裂。对开裂的镦头进行了化学成分、夹杂物及金相组织等检验。结果表明,镦头内部存在表面脱碳、块状碳化物和纵向夹杂物等缺陷是导致PC钢棒镦头开裂的主要原因。 相似文献
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The effect of total oxygen content on the machinability of low carbon resulfurized free cutting steel was studied by means of machinability tests, metallographic, and scanning electron microscopy observation. The results showed that the total oxygen content had a notable effect on the machinability of SAE 1215 steel. The best machinability of the steel in terms of tool life and surface roughness could be obtained by controlling the total oxygen content at 0.0105 and 0.0125 wt%. When total oxygen content in the steel was less than 0.0105 wt%, the machinability of the steel was increased with the increase of total oxygen content because of the significant reduction of the aspect ratio of MnS inclusions. However, when total oxygen content in the steel was more than 0.0125 wt%, the machinability of the steel was deteriorated dramatically with the increase of total oxygen content, which was attributed to that the amount and the size of oxide inclusions (MnO–Al2O3, MnO–SiO2, and 2MnO–SiO2) with high hardness and high melting point both had a significant increase, and some MnS inclusions were also wrapped by the MnO–SiO2 and 2MnO–SiO2 hard oxides. Furthermore, the tool wear would reach the maximum when total oxygen in the steel rose to 0.0150 wt%. 相似文献