Studies on induction hardening of powder-metallurgy-processed Fe-Cr/Mo alloys

Induction hardening of dense Fe-Cr/Mo alloys processed via the powder-metallurgy route was studied. The Fe-3Cr-0.5Mo, Fe-1.5Cr-0.2Mo, and Fe-0.85Mo pre-alloyed powders were mixed with 0.4wt%, 0.6wt%, and 0.8wt% C and compacted at 500, 600, and 700 MPa, respectively. The compacts were sintered at 1473 K for 1 h and then cooled at 6 K/min. Ferrite with pearlite was mostly observed in the sintered alloys with 0.4wt% C, whereas a carbide network was also present in the alloys with 0.8wt% C. Graphite at prior particle boundaries led to deterioration of the mechanical properties of alloys with 0.8wt% C, whereas no significant induction hardening was achieved in alloys with 0.4wt% C. Among the investigated samples, alloys with 0.6wt% C exhibited the highest strength and ductility and were found to be suitable for induction hardening. The hardening was carried out at a frequency of 2.0 kHz for 2-3 s. A case depth of 2.5 mm was achieved while maintaining the bulk (interior) hardness of approximately HV 230. A martensitic structure was observed on the outer periphery of the samples. The hardness varied from HV 600 to HV 375 from the sample surface to the interior of the case hardened region. The best combination of properties and hardening depth was achieved in case of the Fe-1.5Cr-0.2Mo alloy with 0.6wt% C.     

基于路用性能的石灰-钢渣稳定土试验分析

基于路用性能设计正交试验,研究了影响石灰-钢渣稳定土抗压强度的4种因素.结果表明,对于石灰-钢渣稳定土初期抗压强度,石灰含量影响最大,钢渣影响较小;但对于其后期抗压强度,钢渣掺量的影响明显增强,且钢渣粒径大小对后期强度增长速率的影响较大.试验结果对比发现,石灰-钢渣稳定土具有较高的无侧限抗压强度和加州承载比,满足《公路路基设计规范》(JTG D30-2015)和《公路路面基层施工技术细则》(JTG/T F20-2015)的要求,表明可以使用钢渣代替部分石灰或水泥应用于高速公路路床填料.     

Reliability Analysis Based on a Nonlinear Fatigue Damage Accumulation Model

A modified nonlinear fatigue damage accumulation model based on the Manson-Halford theory was presented,and the new model was developed for fatigue life prediction under constant and variable amplitude loading, which took the effects of the load interactions and the phenomenon of material＇s strength degradation into account. The experimental data of the 30 Cr Mn Si A and the LY-12 cz from literature were used to verify the proposed model. And from the good agreement between the experimental data and predicted results,we can see it clear that the proposed method can be applied to predicting fatigue life under different loadings.     

基于SHPB试验的高速铁路CRTSⅡ型CA砂浆动态性能

采用分离式霍普金森压杆(Split Hopkinson Pressure Bar,SHPB)试验研究了高速铁路CRTS II型水泥乳化沥青砂浆(CA砂浆)的动态力学性能,并建立了CRTS II型CA砂浆的动态本构关系模型.结果表明:随着应变率的增大,CRTS II型CA砂浆峰值强度逐渐增加,但增加速率随应变率的增大而减小,当应变率从44.17增加至54.79 s-1和从54.79增加至108.47 s-1时,峰值强度分别增加了初始峰值强度的52.28%和7.5%,弹性模量随应变率的变化规律性较差;应变率越大,破坏时的贯通裂纹越多,碎裂程度越大;CRTS II型CA砂浆的比能量吸收随着应变率的增大而增大.所建立的动态本构模型拟合曲线与试验曲线具有较好的一致性.     

Z-164D溶液对铝土矿强度的影响及其作用机理

以Z-164D为助磨剂，对广西田阳铝土矿进行了邦德球磨功指数试验和单轴抗压强度试验.结果表明:铝土矿经水和Z-164D溶液浸泡后，邦德球磨功指数分别下降了105%和379%，单轴抗压强度分别下降了2684%和4279%.红外光谱分析及X射线能谱微区元素分析表明，Z-164D只能在铝土矿表面发生物理和化学吸附，并不能够渗入铝土矿内部.建立了Z-164D溶液对铝土矿强度影响的作用机理模型，水分子与Z-164D相互促进，共同导致铝土矿缺陷程度增加、强度降低.     

树脂复合减振钢板法向黏结强度与扩孔性能的试验研究

为数值模拟分析时有效地预测树脂复合减振钢板成形过程中的失效形式，设计了测量两表层钢板之间法向黏结强度的试验方法，获得了树脂复合减振钢板的法向黏结强度；并设计了测试树脂复合减振钢板扩孔成形性能的试验模具，获得了极限扩孔率.试验结果表明：树脂复合减振钢板和单层钢板的差异在于成形性能参数和工艺参数不同；要将复合减振钢板成功地应用于工业生产中，必须针对复合减振钢板的变形特点而设定新的失效评判标准，并开发新的检验手段.     

塑料门窗质量影响的因素分析

本文介绍了塑料门窗的加工制作安装过程中各种对门窗质量的影响因素,并进行了分析,结合实际工作经验指出了具体的要求和措施,从而保证了塑料门窗的质量.     

核心力量训练在排球运动员力量训练中的作用探析

近年来,核心力量训练在体育运动中的运用已成为很多人关注的焦点,特别是运动员核心力量训练的研究。本文通过对核心力量定义的界定,论述了排球运动员核心力量训练意义和作用,指出排球运动员核心力量训练的内容及方法,旨在为广大同仁提供参考。     

自然煤矸石轻骨料混凝土配合比设计

为改善混凝土的自重较大的问题并提高其韧性、抗裂性和耐久性,在理论研究的基础上,提出一套聚丙烯纤维自燃煤矸石轻骨料混凝土配合比设计方法,运用此方法得出混凝土的配合比,及聚丙烯纤维轻骨料混凝土的抗压、抗折、劈裂抗拉强度实验数据,为其在今后的应用提供了一定的理论依据。     

玄武岩纤维对不同胶凝材料混凝土的强韧化效应

为了研究玄武岩纤维对不同胶凝材料混凝土的强韧化效应,制备了玄武岩纤维增强普通硅酸盐水泥混凝土BFROPCC与玄武岩纤维增强地质聚合物混凝土BFRGC.采用φ100mm SHPB试验装置,分别研究了BFROPCC与BFRGC的冲击力学性能,并分析了玄武岩纤维对普通硅酸盐水泥混凝土OPCC与地质聚合物混凝土GC的强韧化效应...