共查询到10条相似文献，搜索用时 50 毫秒
1.
2.
3.
4.
对2005年同时颁布的两个射线检测标准GB/T3323—2005和JB/T4730.2—2005进行了对比分析。对两个标准的内容差异逐一进行了解析。阐述了各自标准的制定原则以及参考的国外标准,有利于更加深入地理解和使用GB/T3323—2005和JB/T4730.2—2005标准。 相似文献
5.
21射线源至工件表面的最小距离21.1对比内容GB/T3323与JB/T4730规定基本相同:所选用的射线源至工件表面的距离f应满足下式要求,即A级检测技术时f≥7.5d·b2/3,B级检测技术时f≥15d·b2/3(d为有效焦点尺寸,b为工件表面至胶片距离)。21.2内容解析(1)JB/T4730比GB/T3323多一项AB级规定,即AB级检测时f≥10d·b2/3。(2)GB/T3323比JB/T4730多一项对裂纹检出的规定,即①用A级技术时,若须检出平面型缺陷,则最小距离fmin应与B级同,以使Ug减半。②对裂纹敏感性大的材料有更为严格的技术要求时,应使用灵敏度比B级更优的技术进行透照。22γ射线照相曝光量22.1对比内容GB/T3323:用γ射线照相时,射线源到位的往返传送时间应不超过总曝光时间的10%。JB/T4730:采用γ射线源透照时,总曝光时间应不少于输送源往返所需时间的10倍。22.2内容解析GB/T3323与JB/T4730基本一致。23散射线控制23.1对比内容GB/T3323提出使用铅光阑和滤板。为减少散射线的影响,应利用铅光阑等将照射线尽量限制在被检区段;采用192Ir和60Co射... 相似文献
6.
9像质计(IQI)9.1对比内容GB/T3323采用线型像质计和阶梯孔型像质计,引用标准EN462-1《射线照相影像质量第一部分:概念,丝型像质计及像质数值的确定》和EN462-2《射线照相影像质量第二部分:概念,阶梯孔型像质计及像质数值的确定》。JB/T4730.2只采用线型像质计(普通和专用(等径丝)像质计两种)。引用标准JB/T7902—1999《线型像质计》和HB7684—2000《射线照相用线型像质计》以及附录F《专用像质计》。9.2内容解析(1)GB/T3323与JB/T4730.2关于像质计规定的差异在于①JB/T4730.2未采用孔型像质计,主要考虑孔型像质计应用不普遍,推广无必要。②GB/T3323容许使用“射线吸收系数小于被检材料”的像质计,ASME也容许使用比被透照材料射线吸收性能低的合金材料制作的像质计,但JB/T4730.2无类似规定。(2)实际使用时,铁(Fe)像质计可用于镍(Ni)、铜(Cu)材料的照相;不可用于钛(Ti)、铝(Al)材料的照相。(3)JB/T4730适用的厚度扩大到2~400mm,其引用标准JB/T7902—1999规定的金属丝直径范围不能满足要求,故当时引用H... 相似文献
7.
In the investigations presented here, the feasibility of producing magnetic–nonmagnetic bimetals made of 316L/17-4PH and 316L/Fe powders by micro-metal injection moulding process (μ-MIM) was studied. In order to achieve sound replication of small specimens with dimensions less than 1 mm, very fine powders with mean particle sizes in the range of 3–7 μm were used. A wax–polymer binder system specially designed for micro-moulding was used to make up the feedstock. The isothermal and non-isothermal sintering behaviour of the moulded components was evaluated under hydrogen atmosphere. The effect of powder-binder-ratio of the feedstock, master alloy addition, and sintering conditions on the co-sintering compatibility between the components was investigated. In this study, 316L and 17-4PH showed the best co-sintering compatibility and sound joining of the materials was achieved. When combining 316L and iron, using a 316L master alloy (MA) mixed from NiCrMo and iron powder reduced the mismatch incompatibility with plain iron from 12.7% to 1.6%. So the 316L/17-4PH and 316L MA/Fe were found to be suitable for micro-co-injection moulding. The systems can be used for fabrication of small magnetic–nonmagnetic bimetals with contact areas less than 1 mm2. 相似文献
8.
9.
The kinetic mechanisms of dehydriding reaction in La0.8M0.2Ni5 and LaNi4.5T0.5 were comparatively investigated by the Chou model and the first order model, and the former was superior to the latter from the comparison of theoretical calculated results and experimental data. According to the characteristic time (tc) in the Chou model, substituting La (tc = 71.36 s) with Ce (tc = 35.64 s), Nd (tc = 30.82 s) and Pr (tc = 28.86 s) increased the dehydriding reaction rate, but partial substitution of Ni (tc = 71.36 s) with Co (tc = 102.29 s), Fe (tc = 116.70 s) and Cu (tc = 120.62 s) decreased the hydrogen desorption reaction rate. The Chou model was also used to discuss the effect of different amount of Ni substituted with Fe and Co. The dehydriding reaction rates of La(Ni1−xFex)5 increased with x leveling from 0 to 0.20 but decreased with x increasing from 0.20 to 0.30, while that of LaNi5−yCoy decreased with increasing the amount of Co from 0 to 3.00. In addition, the Chou model was successfully applied to predicting the kinetic properties of LaNi4.8Sn0.2 at 40 °C and 60 °C, which exhibited an excellent agreement with the experimental data. 相似文献