汽车后桥齿用22CrMoH热轧圆钢带状组织控制

围绕汽车后桥齿用22CrMoH钢,通过开展连铸正交试验,优化连铸过程电磁搅拌工艺,改善连铸坯横截面成分偏析,在轧制过程中采用大压下量的开坯轧制工艺,在奥氏体未再结晶区进行多道次大压下量变形轧制,促进圆钢心部组织动态再结晶,从而改善齿轮钢热轧圆钢一次带状组织,改善汽车后桥齿轮热处理变形.采用上述工艺技术制备的重载汽车后桥...     

齿轮钢大圆坯的铸态组织及轧制遗传性

基于φ500 mm大圆坯连铸连轧生产22CrMoH汽车桥齿钢的工艺,通过对铸坯低倍组织及高倍金相组织、轧后带状组织系统分析,开展了齿轮钢大圆坯铸态组织及轧制遗传性研究。研究发现,22CrMoH齿轮钢连铸大圆坯近表面细晶区、柱状晶区、中心等轴晶区的枝晶尺寸存在明显差异;自表面至芯部二次枝晶间距逐渐增加,退火状态下枝晶主干位置以铁素体为主,枝晶间以珠光体为主;轧后带状组织形态主要受铸态组织二次枝晶间距和轧制变形的影响;轧后退火态铁素体带宽自表面至芯部呈现增加趋势。     

改善齿轮钢SAE8620H碳偏析的连铸工艺研究及应用

齿轮钢宏观碳偏析会加重带状级别,影响齿轮热处理变形。最根本解决方法是控制连铸坯碳偏析,在合适的连铸工艺拉速下采用优化结晶器电磁搅拌参数、动态末端电磁搅拌、控制钢水过热度及优化二冷配水的技术手段改善了连铸坯截面碳偏析指数及碳极差。实践结果表明,选择合适的连铸工艺参数及动态末搅技术能够大幅度提升铸坯内部质量,降低齿轮钢SAE8620H宏观碳偏析,达到9点碳极差不高于0.025%、碳偏析指数为0.95~1.05的水平,有效降低了齿轮钢带状级别。同时,轧制圆钢加工成齿轮后热处理变形量小、变形趋势好,产品质量得到了客户的认可。     

均匀化退火加等温正火工艺对20CrMoH齿轮钢组织和性能的影响

研究了均匀化退火加等温正火对20CrMoH齿轮钢组织、硬度及齿轮最终热处理畸变的影响。结果表明,均匀化退火加等温正火处理能够改善20CrMoH钢的带状组织,使硬度分布均匀,并使齿轮的最终热处理畸变量不超过30μm。     

带状组织对22CrMo钢棒材淬火特性的影响

运用DIL805A热膨胀相变仪对热轧态和退火态22CrMo齿轮钢试样的淬火膨胀性能进行测定,研究了带状组织对钢各向异性的影响,通过光学显微镜、扫描电子显微镜观察并分析显微组织。结果表明,含有带状组织的22CrMo齿轮钢不同方向试样的淬火变形量呈现明显各向异性,垂直于轧制带的膨胀量明显大于轧制带方向,不同带状组织的合金元素富集程度不同,导致相变产生的塑性应变制约相邻带的膨胀变形。热轧态22CrMo齿轮钢淬火膨胀无规律性;而退火钢的淬火膨胀特性有明显规律,奥氏体化保温时间越长,碳化物溶解充分,淬透性越高。     

连铸坯形对变速箱零部件热变形的影响

热处理变形是渗碳齿轮热处理过程中常见问题,影响齿轮啮合精度,严重时可导致齿轮报废。连铸坯形是影响齿轮钢热变形的重要因素之一。本文研究了连铸坯形对变速箱齿轮热处理变形的影响。结果表明,在淬透性相近和相同热处理工艺下,圆形的连铸坯形轧制钢材制造的齿轮热处理变形趋势较方坯稳定,热变形较均匀。方形连铸坯制造的齿轮化学成分偏析较明显且组织不均匀,是导致其热处理变形稳定性较差的主要原因。     

22CrMoH钢齿轮锻件等温退火工艺改进

我厂采用22CrMoH钢锻造加工的“EQ-153”汽车后桥从动圆锥齿轮锻件(见图1所示)。该钢主要化学成分(质量分数，％)为：0．19～0．25C，0．17～0．37Si．0．55～0．90Mn，0．85～1．25Cr，0．35～0．45Mo，要求J15为36-42HRC。等温退火技术要求金相组织为均匀铁素体 片状珠光体，带状组织≤3级，魏氏组织0级，晶粒度5～8级，硬度160-210HB。     

热轧工艺对钢/铝复合板抗弯变形性能的影响

采用热轧法制备了钢/铝复合板,研究了轧制温度、保温时间和压下量对钢/铝板力学性能的影响规律。结果表明,2道次轧制时,低温长时间或高温短时间热处理能提高板材抗弯变形性能;钢/铝复合板的抗弯循环次数随压下量的增大先增大后减小。当压下量为85%时,90°弯折循环45次界面不开裂,最大伸长率达21%;1道次轧制时,90°弯折循环不到20次,伸长率不到14%。最佳轧制工艺为:第2道次550℃保温15 min,85%压下量。     

汽车减速器用齿轮钢的组织分析及致裂因素研究

以汽车减速器齿轮用22Cr Mo H钢为研究对象,对其不同热处理工艺条件下硬度、组织及致裂机理进行研究。结果表明,齿轮中裂纹经常出现在大模数齿轮上,这是由于在生产过程中热处理工艺的不合理造成材料淬火应力的产生,导致带状组织的形成,降低了钢的力学性能。     

连铸冷却强度对钢材带状组织级别影响的试验研究

江苏沙钢集团淮钢特钢股份有限公司以40Cr钢为试验钢种,通过调整断面200 mm×200 mm的连铸二冷强度,并将不同冷却强度条件下生产的钢坯以同样的轧制工艺轧制,对比检验轧材带状组织级别,来研究连铸二冷强度对带状组织的影响。试验表明：通过提高连铸二冷强度,可以有效改善铸坯成分偏析,降低轧材带状组织级别,基本可以将轧材带状组织级别控制在1.5级以内。     

Chemical Aspects of Machining Processes

Machining processes used to create surfaces are influenced by the mechanical, thermal, and chemical loading in the contact zone. In addition, the tribo-physical and tribo-chemical interactions between the cutting tool, workpiece, metalworking fluid and surrounding medium have an influence on the properties of the resulting surface. In order to design efficient machining processes and control the chemical state of the surface produced, a basic understanding of the chemical mechanisms in the contact zone is needed. The chemical effects of metalworking fluids on the processes of machining and grinding are discussed, including the chemical interactions which occur between the various participating surfaces. The impact of the resulting chemical state of the surface produced is addressed.     

Review and analysis of microbiologically influenced corrosion: the chemical environment in oil and gas facilities

Microbiologically influenced corrosion (MIC) is a complex phenomenon requiring integrated knowledge of multiple disciplines to better manage and mitigate impacts. The chemical environment (e.g. produced water, soured oil) plays an important role in MIC. Chemical reactions and phase changes due to temperature, pressure, pH and to a lesser extent salinity, impact microbial activities which in turn influences the surrounding chemical environment leading to corrosion. The chemical–microbial interactions complicate the understanding of chemical species transformation and partitioning behaviour in gas, water and oil and subsequent impact on corrosion. In this paper, a review of the complex chemical transformations of chemical species resulting from biotic and abiotic processes are presented. These chemical species can have growth, inhibitory or synergistic effects on microbial activities causing MIC. Microbial activities are found to overlap with chemical/electrochemical processes leading to corrosion. The interaction between chemical environment, environmental factors, electrochemical and microbial processes has been explained with examples from the literature, to understand the contributory effects on MIC. This study will inform further investigation on the chemical environment impacting MIC and model development.     

铝及其合金化学氧化与阴极电泳工艺的配套性

研究了铝合金化学氧化处理与电泳涂装工艺的配套性,探讨了铝合金阴极电泳涂装前表面处理对漆膜性能影响的各种因素,得到了化学氧化与阴极电泳涂装相配套的最佳配方和工艺,所得涂层的附着力及耐蚀性等性能均符合实际生产要求.     

化学造型工艺减排的新认识与新措施

比较分析了化学造型和物理造型的典型工艺及其在铸造过程中的污染物种类及排放量。提出了化学造型(主要是树脂砂型)工艺在混砂、造型、浇注及砂处理工序中减少污染物排放量的新措施。研究表明:化学造型工艺的污染物排放量并不一定比物理造型工艺高,只要用好减排措施,也可以实现清洁生产。     

Die Bedeutung der Schadensanalyse für die Werkstoffentwicklung,Konstruktion und Fertigung im Chemieapparatebau

The importance of case histories with respect to materials, development, design and construction of chemical plant The analysis of case histories can be considered to be an important special steel of materials testing, since the mechanical and chemical stresses and actions characteristic of the chemical industry may give rise to materials behaviour scarcely to be forecasted. The results obtained by such an analysis are the basis for decisions concerning the development of materials with increased resistance to chemical, mechanical and thermal actions; these improvements are achieved by addition of specific alloying elements variations of the materials productions processes as well as mechanical and thermal treatment. The analysis may as well yield important results concerning equipment design, the aim being a design combining a minimum of mechanical stresses and a maximum of chemical resistance; important aspects in this respect are plant excessibility and materials behaviour under welding conditions.     

超细片状银粉的制备技术研究进展

超细片状银粉比传统大尺寸银粉可更好地满足电子产品发展需求。对机械球磨法和化学还原法2种制备超细片状银粉方法进行了对比分析。球磨法产率高、成本低,但易引入杂质且技术指标难保持一致;化学法制备的银粉形貌粒径均一性高,但产率低。介绍了化学还原法的技术特点,对其生长机理进行了分析。提出对球磨工艺的深入研究,以及化学法中保持高品质银粉情况下提高反应体系浓度,是超细片状银粉制备技术的研究重点。     

非晶态Ni-Mo-P合金耐蚀性研究

从理论上分析了金属腐蚀的原因及实质,论述了不同合金层具有不同的化学性质,指出非晶合金具有特殊的化学性质,这与它的结构有关。并且试验研究了具有这种特殊非晶结构的Ni-Mo-P合金层的耐蚀性。在大量实验的基础上,确定了获取三元合金镀层的工艺配方,即15～25g/L硫酸镍,15～20g/L次亚磷酸钠,3～5g/L钼酸钠,另外含少量的络合剂和稳定剂。经结构分析所得合金层为非晶态结构。腐蚀实验证明该镀层具有很好的耐有机溶剂及有机酸和盐的性质;有耐强碱和耐浓硫酸的特性。     

Capability of thermodynamic calculation in the development of alloys for deposition of corrosion‐protection coatings via thermal spraying

The capability of thermodynamic calculations for the development of materials for corrosion protection of steels via thermal spraying is illustrated in several practical examples. Although the thermodynamic calculations are usually performed for the equilibrium state, they can yield important information even about fast chemical reactions that are far from the equilibrium conditions. The relevance and reliability of thermodynamic calculations can be improved significantly if their results are complemented by chemical and microstructural analyses. In this contribution, details on the melting and alloying processes in technically relevant nickel‐based alloys were obtained from the combination of the thermodynamic calculations, differential thermal analysis, local chemical analysis using scanning electron microscopy with energy dispersive spectroscopy of characteristic X‐rays and X‐ray diffraction analysis. Furthermore, the results of the thermodynamic calculations performed on nickel‐based alloys clarified the role of individual chemical elements dissolved in the alloys for the corrosion resistance of the alloys and thus they contributed to the improvement of the chemical stability of these alloys during the chemical reaction with gaseous substances containing chlorine.     

Factors of chemical activity of metal surface

In this work, the factors of the chemical activity of the metal surface are studied in terms of their physical nature. The concepts of chemical bonding, e.g., the equalizaton of electronegativities and maximum chemical hardness, are related to the theories of a metal surface response to external electromagnetic excitations. The metal surface is considered in terms of the electronic gas edge model (Kohn and Mattsson). The equations of the Landau-Migdal theory of the electronic Fermi liquid are used to describe the effect of a field’s interactions with electrons. An analysis of the solution of a system of equations showed that the parameters of the metal system’s response to the external electric field (chemical potential of the electron and local and integral density of one-particle electronic levels near the Fermi level) are identical to the main characteristics of its chemical activity according to Yang and Parr (Yang, W., Parr, R.G., “Proc. Natl. Acad. Sci. United States,” 1985, vol. 82, p. 6723): electronegativity, local and global chemical softness. The model under consideration contains no artifacts. The authors believe that the method is promising for further studies of fundamentals of the nature of physicochemical phenomena at interfaces.     

等离子喷涂羟基磷灰石涂层的化学不均匀性和浸泡行为

利用X射线衍射仪（XRD）、电子探针（EPMA）等检测手段,对纯钛表面等离子喷涂羟基磷灰石（HA）涂层的化学不均匀性和浸泡行为以及热处理对涂层化学不均匀性的影响进行了研究.结果表明,喷涂后的涂层中存在化学不均匀性,原始颗粒越小不均匀性越严重;去离子水浸泡后,涂层表面析出Ca2P2O7等化合物,浸泡时间越长、原始颗粒越小的涂层析出物越多;热处理能使非晶相和分解相重新生成HA,提高涂层结晶度而消除非均匀现象.