20MnCr5圆棒锯切困难原因分析

某厂在锯切20MnCr5圆棒过程中锯条容易断裂，采用光学显微镜(OM)和扫描电子显微镜(SEM)等观察分析手段，对锯条容易断裂的原因进行分析。分析结果表明：锯条断裂的原因为加工20MnCr5过程中粘刀崩齿。针对此类加工缺陷，提出了相应的改进措施。     

Total Site Hydrogen Integration with fresh hydrogen of multiple quality and waste hydrogen recovery in refineries

This paper proposes a novel method combining Pinch Methodology and waste hydrogen recovery, aiming to minimise fresh hydrogen consumption and waste hydrogen discharge. The method of multiple-level resource Pinch Analysis is extended to the level of Total Site Hydrogen Integration by considering fresh hydrogen sources with various quality. Waste hydrogen after Total Site Integration is further regenerated. The technical feasibility and economy of the various purification approaches are considered, demonstrated with a case study of a refinery hydrogen network in a petrochemical industrial park. The results showed that fresh hydrogen usage and waste hydrogen discharge could be reduced by 21.3% and 67.6%. The hydrogen recovery ratio is 95.2%. It has significant economic benefits and a short payback period for Total Site Hydrogen Integration with waste hydrogen purification. The proposed method facilitates the reuse of waste hydrogen before the purification process that incurs an additional environmental footprint. In line with the Circular Economy principles, hydrogen resource is retained in the system as long as possible before discharge.     

0CrMnTiH齿轮钢的淬透性计算及窄淬透性带控制

采用非线性方程计算法计算20CrMnTiH钢末端淬透性,只需利用生产实际数据加以修正,就能进行精确的淬透性计算和预报,与实测值偏差不超过2HRC。采用化学成分设计和控制,保证20CrMnTiH钢△[C]不超过0.007%,△[Si]波动不超过0.04%,△[Mn]、△[Cr]不超过0.02%,△[Ti]不超过0.01%,△[Alt]不超过0.010%,[Ni]、[Cu]不超过0.05%,[Mo]、[W]、[V]不超过0.03%,[P]、[S]不超过0.020%,[N]和[B]分别不超过0.006 0%和0.0005%,并控制碳偏析指数不超过1.035%,可实现国际先进水平的末端淬透性HRC4带宽控制。     

Scheduling distributed flowshops with flexible assembly and set-up time to minimise makespan

The scheduling problems under distributed production or flexible assembly settings have achieved increasing attention in recent years. This paper considers scheduling the integration of these two environments and proposes an original distributed flowshop scheduling problem with flexible assembly and set-up time. Distributed production stage is deployed several homogeneous flowshop factories that process the jobs to be assembled into final products in the flexible assembly stage. The objective is to find a schedule, including a production subschedule for jobs and an assembly subschedule for products, to minimise the makespan. Such a scheduling problem involves four successive decisions: assigning jobs to production factories, sequencing jobs at every factory, designating an assembly machine for each product and sequencing products on each assembly machine. The computational model is first established, and then a constructive heuristic (TPHS) and two hybrid metaheuristics (HVNS and HPSO) are proposed. Numerical experiments have been carried out and results validate the algorithmic feasibility and effectiveness. TPHS can obtain reasonable solutions in a shorter time, while metaheuristics can report better solutions using more yet acceptable time. HPSO is statistically comparable yet less robust compared with HVNS for small-scale instances. For the large-scale case, HPSO outperforms HVNS on both effectiveness and robustness.     

LLM-105/CL-20基高能钝感PBX的制备与性能表征

为满足含能材料高能钝感的要求,以CL-20为主体炸药,LLM-105为钝感剂,采用溶液水悬浮法制备了LLM-105质量分数分别为10%、20%、30%的3种LLM-105/CL-20基PBX。通过扫描电子显微镜(SEM)、粉末X射线衍射仪(PXRD)和差示扫描量热仪(DSC)对样品的形貌、晶体结构和热性能进行表征,并测试其机械感度;采用EXPLO5软件计算了其爆轰参数。结果表明,LLM-105/CL-20基PBX样品呈类球形,颗粒密实,粒径约为500μm;PBX中各组分的晶体结构未发生改变;3种配方的热安定性都较好,且随着钝感剂LLM-105含量的增加,LLM-105/CL-20基PBX的热爆炸临界温度呈递增趋势;与原料CL-20相比,3种LLM-105/CL-20基PBX的特性落高分别提高了25.88、33.68、37.18 cm,摩擦爆炸概率分别下降29%、38%、45%;LLM-105质量分数为10%的LLM-105/CL-20基PBX的特性落高与PBX-9501相当,而LLM-105质量分数为20%和30%的LLM-105/CL-20基PBX分别比PBX-9501高16.6%和25.12%;理论爆速分别高381.76、279.2、82.03 m/s。3种配方LLM-105/CL-20基PBX炸药的爆轰性能明显优于PBX-9501。     

Formation mechanism and microstructure evolution of Ba2Ti9O20 ceramics by reaction sintering method

Ba₂Ti₉O₂₀ single-phase ceramics were prepared by reaction sintering method using TiO₂ and BaCO₃ as raw materials after heat treating at 1150°C for 10 hours. Furthermore, the formation mechanism and microstructure evolution of Ba₂Ti₉O₂₀ ceramics prepared by reaction sintering method were investigated. The formation behavior of Ba₂Ti₉O₂₀ phase was analyzed from the perspective of diffusion, where the reaction activation energy required for the process was calculated to be about 386.17 kJ/mol. Combined with the scanning electron microscopy and the energy dispersive spectrometer, it was revealed that the pores on Ba₂Ti₉O₂₀ grains in the process of reaction sintering might be caused by the absence of oxygen element. Meanwhile, the reason for the roughness of ceramic surface was that the local inhomogeneous distribution of barium on the surface of Ba₂Ti₉O₂₀ grain leaded to the enrichment of titanium.     

增进核电焊材用钢508 Ⅲ洁净度的工艺实践

核电焊材用钢508 Ⅲ（/%:0.09~0.12C,0.30~0.40Si,1.45~1.65Mn,≤0.008P,≤0.008S,0.45~0.60Mo,0.60~0.75Ni）的生产工艺流程为20t EAF-LF-VD-4t铸锭-锻造150 mm×150 mm坯-轧制Φ5.5mm盘条。采用精选炉料,以及高碱度渣、高FeO含量,钢水温度1550~1570℃等措施控制,电弧炉终点[P]≤0.002%,并选用低磷合金,使钢中磷含量≤0.006%;LF采用硅钙合金沉淀脱氧,SiC粉扩散脱氧、CaO-Al₂O₃-SiO₂渣系,碱度5.0~5.5,VD真空度≤67Pa,Ar流量30~50 L/min,保护浇铸等措施后,3炉钢的分析结果表明,钢中气体含量为1.3×10^-6~1.5×10^-6[H],10×10^-6~14×10^-6[O]和44×10^-6~58×10^-6[N],满足核电焊材用钢508Ⅲ洁净度的要求。