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101.
102.
裂纹张开位移的预测方法 总被引:2,自引:0,他引:2
把不同温度下的裂纹张开位移(CTOD)试验数据,用灰色理论中的累加方法,进行二次累加。可以使一组没有规律的数据,成为一条光滑的曲线。然后利用回归理论中的多项式模拟曲线,对其试验数据进行了预测,提出根据试验数据确定出预测数据的可能的区间范围。计算实例表明,其预测精度较高。 相似文献
103.
Deng CaiyanZhang YufengHuo LixingSchool of Material Scienceand Engineering Tianjin University Tianjin China 《机械工程学报(英文版)》2005,18(3):389-392
0 INTRODUCTIONFlaw assessment concepts based on fracture mechanics arebeing increasingly used in industrial regulations and standards. Aconsiderable number of guidelines and procedures are availablewhich are partly based on each other but also exhibit sig… 相似文献
104.
V. V. Chaudhari D. M. Kulkarni 《Fatigue & Fracture of Engineering Materials & Structures》2015,38(7):851-859
Fracture tests of extra deep drawn steel sheet were carried out at ambient temperature to investigate the effect of loading rate on fracture toughness. To determine fracture limits, fracture tests and finite‐element cohesive zone model simulation tool are used. Fracture tests are conducted at various loading rates (0.1–2.5 mm min?1). An alternative constant traction separation law is used to account for maximum load and large load line displacements. Experimental findings, as well as cohesive zone model, show that the loading rate has no significant effect on fracture toughness till 0.4 mm min?1; however, there is a sharp decrease in fracture toughness beyond 0.4 mm min?1. 相似文献
105.
按照EN10225标准要求,对75 mm厚度规格海洋平台用S355G10+M钢板进行了堆焊硬度试验(BOP)、可控热拘束试验(CTS)以及热输入50 k J/cm埋弧焊对接接头系列力学性能试验,研究了钢板焊接热影响区(HAZ)的淬硬倾向、HAZ冷裂纹敏感性、焊接接头各部位抗拉强度、冲击韧性和裂纹尖端张开位移(CTOD)值的变化情况。结果显示S355G10+M厚钢板的HAZ最高硬度、焊接钢板冷裂纹、埋弧焊对接接头抗拉强度、低温冲击功均值、CTOD值等各项性能指标良好,满足海洋平台的焊接生产要求。 相似文献
106.
根据BS74 4 8断裂韧度试验标准 ,对X6 5管线钢焊接接头的低温 (0℃ )裂纹尖端张开位移 (CTOD)进行了测试。取尺寸为B× 2B(B为试样厚度 )、缺口方向为NP的试样进行三点弯曲试验 ,然后由所得到的 0℃下母材、焊缝和热影响区 (HAZ)的P -V曲线来计算CTOD值 ,并对试验结果进行了讨论和总结。对显微组织的分析表明 ,共有3个HAZ试件不满足裂纹尖端不超过熔合线 0 .5mm且落在粗晶区内的要求。该结果恰好与P -V曲线和所得的CTOD值相一致 ,从而解决了试验值分散性大的问题 ,同时为ECA评估提供了重要依据 ,验证了BS74 4 8标准的合理性并体现了它的优越性。 相似文献
107.
For the corrosion protection of natural gas transmission pipelines, two methods are used, cathodic protection and a coating
technique. In the case of cathodic protection, defects are embrittled by hydrogen occurring at crack tips or surfaces of materials.
It is, however, very important to evaluate whether cracks in the embrittled area can grow or not, especially in weld metal.
In this work, on the basis of elastic plastic fracture mechanics, we performed CTOD testing under various test conditions,
such as potential and current density. The CTOD of the base steel and weld metal showed a strong dependence on the test conditions.
The CTOD decreased with increasing cathodic potential and current density. The morphology of the fracture surface showed quasi-cleavage.
Cathodic overprotection results in hydrogen embrittlement at the crack tip. 相似文献
108.
连铸10CrNi3MoV钢裂纹尖端张开位移(CTOD)试验研究 总被引:1,自引:0,他引:1
对电炉模铸及不同批转炉连铸 10CrNi3MoV钢进行了CTOD试验研究 ,并探讨了CTOD特征值与钢板中心偏析关系。结果表明 ,模铸钢板抵抗裂纹早期扩展的能力高于连铸板 ,但连铸板抵抗裂纹失稳扩展能力并不低于模铸板 ;钢板中心偏析使CTOD特征值降低 ;控制碳含量在较低水平 ,或碳含量达上限 (0 .11%C)时采取减轻偏析的有效措施 ,可使连铸 10CrNi3MoV钢具有较高的断裂韧性 相似文献
109.
Microstructural and mechanical properties of laser welded sheets of magnesium AZ31‐HP with and without filler wires This paper describes Nd:YAG laser beam welding experiments carried out on rolled 2.5 mm thick magnesium sheet AZ31‐HP. For the butt welds in flat position, filler wires AZ31X and AZ61A‐F were used, diameter 1.2 mm. The microstructure and mechanical properties of the different laser beam welded joints were examined and compared with one another. The obtained results show that the laser beam welding of AZ31‐HP sheet is possible without hot crack formation, both without and with filler wires. The determined tensile strength, ductility, fracture toughness and microhardness of laser beam welded joints without filler wire were not effected by AZ31X nor AZ61A‐F. By use of these filler wires loss of zinc was minimized and the shape of weldments was optimized. The values of fracture strength, yield strength and microhardness of the joints and base material are quite similar. It is found that the ductility of the joints is lower than the base materials due to the heterogeneous microstructure of the fusion zones and geometrical notches of the weld seams. Both, weld and base material of AZ31‐HP, showed stable crack propagation. Furthermore, for base material slightly lower fracture toughness values CTOD than for the joints were determined. 相似文献
110.