Effect of solution cooling rate on the γ'' precipitation behaviors of a Ni-base P/M superalloy

The effect of cooling rate on the cooling "/' precipitation behaviors was investigated in a Ni-base powder/metallurgy (P/M)superalioy (FGH4096).The empirical equations were established between the cooling rate and the average sizes of secondary and tertiary γ' precipitates within grains and tertiary γ' precipitates at grain boundaries,as well as the apparent width of grain boundaries.The results show that the average sizes of secondary or tertiary γ' precipitates are inversely correlated with the cooling rate.The shape of secondary γ' precipitates within grains changes from butterfly-like to spherical with the increase of cooling rate,but all the tertiary γ' precipitates formed are spherical in shape.It is also found that tertiary γ' may be precipitated in the latter part of the cooling cycle only if the cooling rate is not faster than 4.3℃/s,and the apparent width of grain boundaries decreases linearly with the increase of cooling rate.     

Effect of solution cooling rate on the γ′ precipitation behaviors of a Ni-base P/M superalloy

The effect of cooling rate on the cooling γ′ precipitation behaviors was investigated in a Ni-base powder/metallurgy (P/M) superalloy (FGH4096). The empirical equations were established between the cooling rate and the average sizes of secondary and tertiary γ′ precipitates within grains and tertiary γ′ precipitates at grain boundaries, as well as the apparent width of grain boundaries. The results show that the average sizes of secondary or tertiary γ′ precipitates are inversely correlated with the cooling rate. The shape of secondary γ′ precipitates within grains changes from butterfly-like to spherical with the increase of cooling rate, but all the tertiary γ′ precipitates formed are spherical in shape. It is also found that tertiary γ′ may be precipitated in the latter part of the cooling cycle only if the cooling rate is not faster than 4.3°C/s, and the apparent width of grain boundaries decreases linearly with the increase of cooling rate.     

熔体过热度对Fe_(78)Si_9B_(13)非晶条带磁性能的影响

为了研究合金熔体过热度和退火温度对Fe_(78)Si_9B_(13)非晶条带磁性能的影响,在180、200和230℃3个不同合金熔体过热度下利用单辊法制备了宽142 mm、厚23μm的非晶条带.在350~370℃范围内选取5个退火温度对非晶条带进行纵向磁场退火,并利用硅钢测试仪对退火后的非晶条带进行磁性能测试.结果表明,随着合金熔体过热度的增大,非晶条带的激磁功率和损耗均呈下降趋势.随着过热度和退火温度的降低,非晶条带的磁性能分布区间变窄,但其稳定性增强.适当提高过热度和热处理温度有助于获得具有最佳磁性能的非晶条带.     

Effect of vanadium and chromium on the microstructural features of V–Cr–Mn–Ni spheroidal carbide cast irons

The objective of this investigation is to study the influence of vanadium（5.0wt%–10.0wt%） and chromium（0–9.0wt%） on the microstructure and hardness of Cr-V-Mn-Ni white cast irons with spheroidal vanadium carbides. The alloys＇ microstructural features are presented and discussed with regard to the distribution of phase elements. The structural constituents of the alloys are spheroidal VC, proeutectoid cementite, ledeburite eutectic, rosette-shaped carbide eutectic（based on M7C3）, pearlite, martensite, and austenite. Their combinations and area fraction（AF） ratios are reported to be influenced by the alloys＇ chemical composition. Spheroidized VC particles are found to be sites for the nucleation of carbide eutectics. Cr and V are shown to substitute each other in the VC and M7C3 carbides, respectively. Chromium alloying leads to the formation of a eutectic（γ-Fe ＋ М7С3）, preventing the appearance of proeutectoid cementite in the structure. Vanadium and chromium are revealed to increase the total carbide fraction and the amount of austenite in the matrix. Cr is observed to play a key role in controlling the metallic matrix microstructure.     

钢中残余Mg量对SiMn型复相耐磨铸钢硫化物夹杂形态的影响

探讨了镁变性处理对SiMn复相耐磨钢中硫化物夹杂形态的影响，研究结果表明：镁残余含量Mg残＝0．03 9％与Mg残／S＝1，21是管制友化物的形态和临界值，而SiMn复相耐磨钢硫化物的形态对钢的冲击韧性αK会产生很大影响。     

氮在灰铸铁凝固过程中的作用

在研究氮系孕育剂的基础上,采用微分热分析法和岛津DT30B型差热分析仪探讨了N在灰铸铁共晶和共析凝固过程中的作用行为。     

不同产地粘土热性能研究

通过对上刘庄(土门掌)、外围料、龙洞等不同产地粘土的化学成分分析、物相分析、差热分析和热膨胀特性分析,对不同产地粘土的热性能与物相组成的关系进行了探讨,发现粘土中水铝石含量对陶瓷结合剂强度有重要影响,与含量的关系十分密切.对于陶瓷磨具来说,进入烧成带后,粘土的热膨胀系数越大,强度越小.     

面120区稠油热采增产试验效果分析

八面河油田面120区储层渗透率较低,油层原油粘度较大,出现了热采效果差,地层能量下降快的现象。针对这种情况可采用氮气+蒸汽吞吐技术。实践表明,该项技术的应用提高了井筒隔热效果,降低了热损失,同时又补充了能量,调整了吸汽剖面。需要强调的是在热采过程中,对油层的保护可采用伴蒸汽注入,但这种方法容易造成地层伤害。因此,在采用伴蒸汽方式时,注入防膨效果最佳。