Q235热轧钢板伸长率不合试样的金相分析

分析了Q235热轧钢板伸长率不合格的试样,发现伸长率不合试样的硫化物较多、带状组织较严重;应用统计学方法对比分析了伸长率合格与不合格试样的非金属夹杂物、带状组织、魏氏组织的级别。结果表明,伸长率不合试样的A类夹杂物、带状组织级别较高。硫化物较多、带状组织级别较高是造成伸长率不合格的主要原因。     

压力容器用钢板Q345R延伸率不合格原因分析

针对Q345R锅炉与压力容器用钢板断后伸长率不合格的问题,利用直读光谱仪、金相显微镜、扫描电镜等设备对Q345R断后伸长率不合格试样进行了化学成分、金相组织、断口形貌等方面的检测分析。分析结果表明,钢中的硫化锰夹杂物、贝氏体组织和带状组织是造成Q345R钢板断后伸长率不合格的主要原因。通过提高铸坯炼钢冶金质量、降低锰和硫元素含量、减轻成分偏析、采用合理的控轧控冷工艺、减少异常组织产生等措施,使得Q345R钢板的断后伸长率明显提高。     

低碳中板断后伸长率不合原因分析

对Q235B中板断后伸长率不合格试样进行了详细的物理化学分析，并与合格试样进行了对比，发现不合格试样中存在与板面呈约30℃夹角的裂纹，裂纹内有硫化物类夹杂，级别大于5级；带状组织为B系列3.5级；拉伸断口分层，断裂位呈脆性准解理形态，而周围呈韧窝型塑性断裂形态。此外，连铸坯中存在严重的中间裂纹，认为连铸坯中存在的中间裂纹易造成硫等杂质元素集中分布，而导致Q235B中板断后伸长率不合格。通过对生产工艺进行追溯，改进相应措施，断后伸长率合格率大幅提升。     

Q235B中厚钢板伸长率不合格原因分析

通过利用金相显微镜观察Q235B铜板伸长率不合格试样的组织、夹杂物级别,利用扫描电镜能谱议对试样断口形貌、夹杂物分布、夹杂物成分进行分析,确定造成Q235B钢板延伸率不合格主要是由于铜中夹杂物多,特别是MnS夹杂物较多且分布不均造成的。     

氢脆导致Q235B钢板断后伸长率不合格

某南方钢厂,于梅雨季节期间持续出现Q235B钢板断后伸长率不合格的现象。为查清断后伸长率不合格原因,将同批次断后伸长率不合格与合格的试样进行力学性能试验、化学成分分析、断口形貌分析、金相检验等对比分析。结果表明：钢板中残留的氢元素,最终导致该Q235B钢板断后伸长率不合格,而钢中非金属夹杂物也是断后伸长率不合格的影响因素之一。为了验证上述分析,将该批次钢板进行去氢处理,经处理后的钢板氢脆现象消失,断后伸长率不合格现象得以消除。     

Q390D钢板TMCP工艺优化

针对Q390D钢板抗拉强度高、伸长率低的问题,从终冷温度、取样位置和金相组织等方面分析了原因。认为钢板ACC终冷温度低、头部过冷以及取样过程中头部加工硬化区切除不净等,是导致Q390D钢板抗拉强度高、伸长率低的主要原因。通过优化水冷工艺,调整终冷温度,并规范取样方式,Q390D钢板性能合格率稳定在99%以上。     

Q235-B热轧中板伸长率和冲击不合格原因分析

昆钢Q235-B热轧中板伸长率和冲击合格率出现偏低的情况．选取较有代表性的试样进行化学成分、金相显微镜及电子显微镜的试验分析。结果表明，带状组织及夹杂物对材料的伸长率和冲击韧性有直接影响，带状组织及夹杂物的形成原因进行了讨论，提出了相应的改进措施。     

Q235B钢板冷弯性能和断后伸长率不合格原因分析

通过利用直读光谱仪检测化学成分,利用金相显微镜检测金相组织和夹杂物级别,利用扫描电镜和能谱仪对拉伸试样断口形貌进行分析,发现Q235B钢中P、S含量偏高,导致钢中带状组织加重,沿轧向分布的大量长条状硫化物夹杂成为裂纹源,降低了钢板的横向塑性,导致冷弯试样开裂,拉伸断口出现分层,呈木纹形貌断口,造成Q235B钢板冷弯性能和断后伸长率不合格。采取工艺措施,提高钢的纯净度,有效减少钢中的P、S含量,严格控制钢中的硫化物夹杂的数量和形态,有利于使Q235B钢板冷弯性能和断后伸长率指标合格。     

Q460C中厚钢板伸长率不合格的原因分析

针对热轧Q460C中厚钢板在拉伸试验中出现伸长率不合格的问题,通过对拉伸试样断口形貌、断口区域的金相组织以及低倍硫印检验分析,认为钢板中夹杂物含量较高、中心偏析、中间裂纹和板材带状组织是导致伸长率不合格的主要原因,并提出相应解决措施。     

奥氏体-铁素体区循环形变对Q235钢力学性能的影响

研究开发出了一种钢材组织细化的新方法,即奥氏体-铁素体区循环形变,并采用自行设计的热模拟试样,研究了奥氏体-铁素体区循环形变对Q235钢力学性能的影响规律.结果表明:在大部分变形条件下,采用该方法所得到的Q235钢的杭拉强度大于500MPa,屈服强度大于400MPa,伸长率大于20%,     

Statistical genetics of normal variation in family data for oligogenic diseases

A quadrivariate quantitative genetic analysis detected significant heritabilities for four simulated quantitative traits (Q1-Q4) with additive genetic pleiotropy between traits Q1, Q2, and Q3. Using univariate segregation analysis, we tentatively detected five major loci: one each for Q2, Q3, and Q4 and two, at different maxima, for Q1. Bivariate one-locus segregation analysis identified significant major locus pleiotropy for Q1, Q2, and Q3 only; and suggested identity between one of Q1's major genes and that for Q2, and between the second Q1 major gene and that for Q3. Patterns of linkage, supportive of inferences from the bivariate segregation analyses, were detected between three candidate genes and the major genes for Q1, Q2 and Q4.     

A Lower Bound of the Genus of a Self-amalgamated 3-manifolds

Let M be a compact connected oriented 3-manifold with boundary,Q1,Q2 (∪) (δ) M be two disjoint homeomorphic subsurfaces of (a)M,and h:Q1→ Q2 be an orientation-reversing homeomorphism.Denote by Mh or Mq1=q2 the 3-manifold obtained from M by gluing Q1 and Q2 together via h. Mh is called a self-amalgamation of M along Q1 and Q2 Suppose Q1 and Q2 lie on the same component F'of (δ)M',and F'- Q1 U Q2 is connected.We give a lower bound to the Heegaard genus of M when M'has a Heegaard splitting with sufficiently high distance.     

Identification of the Ped gene at the molecular level: the Q9 MHC class I transgene converts the Ped slow to the Ped fast phenotype

The Ped (preimplantation embryo development) gene, which maps to the Q region of the mouse major histocompatibility complex (MHC), controls the rate of cleavage division of preimplantation mouse embryos and subsequent embryonic survival. Of the ten known MHC class I genes in the Q region of the mouse MHC, four--Q6, Q7, Q8, and Q9--are almost identical and encode similar proteins, all called the Qa-2 antigen. Previous studies have suggested that the Q9 gene encodes the Ped gene. To test this directly, one-cell embryos from the CBA/Ca strain (Ped slow) that is missing the Q9 gene and the Qa-2 antigen were injected with the Q9 gene from the C57BL/10 strain (Ped fast) that possesses the Q9 gene and expresses the Qa-2 antigen. The resulting Q9 transgenic mice were found to express the Qa-2 antigen. In addition, it was found that introduction of the Q9 gene converted the Ped gene phenotype of the recipient strain from slow to fast. Therefore, the Ped gene product is the Qa-2 antigen encoded by the Q9 gene.     

Genetic epidemiologic analysis of quantitative phenotypes using Gibbs sampling

We analyzed two quantitative traits (Q1 and Q2) provided in the 'Common Disease' data set with the aim of detecting both genetic and environmental determinants. We used linear regression for screening measured variables, maximum likelihood segregation and linkage analyses for detecting and localizing unmeasured genes, and Gibbs sampling for joint segregation and linkage analyses with estimation of gene-environment interaction and polygenic effects. For both Q1 and Q2, we successfully detected the unmeasured codominant major gene (MG) that was tightly linked to candidate gene C2. We also detected all of the measured variables used in generating Q1 (age, Q3, candidate gene C5) and Q2 (EF). Although our final models differed slightly from the true data generation models, our multifaceted analytic approach was successful in characterizing the determinants of Q1 and Q2.     

轧制Q值对小口径TA2管材组织和性能的影响

通过改变钛管材冷轧过程中的工艺参数,研究了不同相对减壁量与相对减径量的比值(Q值)对小口径TA2管材组织和性能的影响。结果表明:轧制Q值对管材组织性能影响较大,通过合理控制成品管材的轧制Q值可获得组织性能良好的TA2管材;对于6 mm×1 mmTA2管材,Q值控制在1.65,变形率ε取53.3%时,可获得最佳的强塑性匹配。Q值影响冷加工过程中晶粒的破碎程度、均匀度及织构分布,因此可通过调整Q值的大小来控制管材的组织、织构,进而得到与之相匹配的良好的力学性能。     

Diminished heparin binding of a basic fibroblast growth factor mutant is associated with reduced receptor binding, mitogenesis, plasminogen activator induction, and in vitro angiogenesis

Using modeling of heparin-fibroblast growth factor interactions, we replaced four basic residues of basic fibroblast growth factor (FGF-2) with neutral glutamine residues by site-specific mutagenesis to give the mutants K128Q, K138Q, K128Q-K138Q, R129Q, K134Q, and R129Q-K134Q. The FGF mutants were characterized for their receptor and heparin binding affinities, mitogenic and cell proliferation activities, and their ability to induce plasminogen activator (PA) production and in vitro angiogenesis by cultured endothelial cells. Heparin binding properties and biological activities of the three mutants involving R129 and K134 remained essentially unchanged; however, significant changes for three mutants involving K128 and K138 were found. The KD values for heparin binding for K128Q and K138Q mutants were increased about 10-fold, and that for the K128Q-K138Q double mutant was increased by about 100-fold. The mutant K128Q-K138Q required a 10-fold higher concentration of heparin to promote binding to heparan sulfate proteoglycan (HSPG)-deficient CHO cells transfected with fibroblast growth factor receptor-1 (FGFR1) or to induce DNA synthesis in HSPG-deficient myeloid cells transfected with FGFR1. Binding affinities of the mutants to cell surface receptors on BHK-21 cells, however, were similar to that of wild-type FGF-2. In endothelial cell proliferation assays the activities of K128Q and K128Q-K138Q were about 10-fold lower than that of the wild-type protein, whereas the K138Q mutant exhibited wild-type activity. In addition, the K128Q-K138Q mutant displayed a markedly lowered capacity to induce PA activity in cultured endothelial cells and to form capillary-like structures in an in vitro angiogenesis model.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hand preference and components of I.Q

An account is given of the hand preferences (measured by questionnaire) of 687 individuals living in a Cambridge suburb. The proportions of right, mixed and left handers differed according to the classification used. Verbal and Performance I.Q. component scores were examined in relation to hand preference. For all classifications, left handers' overall Verbal I.Q. was significantly higher than their Performance I.Q. score, whereas right and mixed handers' Performance I.Q. scores were greater than their Verbal I.Q.s. Left handers scored higher than right and mixed handers on Verbal I.Q. but lower on Performance I.Q. The relationships between patterns of handedness, I.Q. component scores and cerebral dominance are discussed.     

热熔浸铝Q235钢在模拟海水环境下的腐蚀行为

以Q235钢材原件、热熔浸铝一次和两次的Q235钢为研究对象,通过模拟海水（质量分数为3.5% NaCl溶液）浸泡试验,对比研究了3种试样在NaCl溶液中的腐蚀行为。利用扫描电镜观测了不同样品在腐蚀前后的表面形貌,利用失重法、交流阻抗等方法研究了热熔浸铝Q235钢的腐蚀速率。结果表明,在NaCl溶液中Q235原件腐蚀速率最快,腐蚀严重,年均腐蚀速率为0.11 mm/a;热熔浸铝一次和两次的Q235钢腐蚀速率相差不大,年均腐蚀速率分别为0.04和0.03 mm/a,热熔浸铝后Q235钢的耐腐蚀性能明显得到提高,说明热熔浸铝是一种有效提高Q235钢耐海水腐蚀性能的手段。     

提高Q345系列钢板冲击韧性的轧制工艺探讨

分析轧制工艺的变化对Q345B级钢板冲击韧性的影响，通过试验确定的控制轧制工艺保证了Q345B、Q345C板的稳定生产，并为Q345D板的开发奠定基础．