镍铁型焊条焊接高强球铁接头云纹实验解析研究

镍铁型铸铁焊条已经相当广泛地用来焊接QT60—2球墨铸铁。然而,研究工作表明,这些焊接接头的强度较低。本文首次利用密栅云纹法研究了单向拉伸焊接接头的受力状况,获得了接头区域的全场位移、应变和应力分布。从焊接接头应变和应力分布的不均匀性,分析了裂纹产生及扩展的原因,用扫描电子显微镜观察了断口形貌,发现有大量的球状物分布在断口上,这可能是导致焊接接头低应力破断的原因。这一次现有助于改进镍铁型铸铁焊条的性能,提高接头的强度。     

MATHEMATIC MODEL FOR FORMABILITY CRITERIA OF SUPERPLASTIC AIR BULGING COMPONENTS

A proposal for two types of press close to die,including blank coming in die and Blank cov-ering die,and four criteria for formability is put forward in the study of the superplastic airbulge forming of the metallic thin wall components.A dimensionless weigh mathematic modelfor the criteria of superplastic air bulge forming is developed to be:Q_w=1.56(WS)/(HF)+2.37(0-π/(180)-r/(r_0)+0.19The superior formability of components is approaching,if Q_W≥1,and the worse,if Q_W<1.Itwas confirmed by practice that the above mentioned model is accurate sufficiently.     

42CrMo钢等离子渗氮动力学的数学模型

在42CrMo钢进行等离子渗氮工艺试验的基础上,参考有关数学关系,利用电子计算机处理实验数据,初步建立了扩散层、化合物层、温度控制的数学模型,实现了微处理机控制等离子渗氮参数.实验还得出CO_2对等离子体渗氮有加速作用.     

PHASE BOUNDARIES OF SINGLE-PHASE ε-AND γ′-FIELDS IN Fe-C-N PHASE DIAGRAM

由低温下的溶解度导出氮在α-Fe中的活度数据,求得了Fe-C-N三元系中各二元交互作用系数,并导出了该系中的分配方程组.依此在PDP-11/23计算机上计算了γ′及ε单相区界域.计算结果表明:原Naumann和Langenscheid相图中的γ′相区正确,但ε相区需修正.计算结果与Wells及Bell的大部分实验结果符合.采用石墨为标准态(见附录证明)的计算也得到相同结论.     

DYNAMIC MECHANICAL BEHAVIOURS OF HIGH Mo AUSTENITIC STAINLESS STEEL DURING HOT DEFORMATION

The dynamic mechanical behaviours of super low carbon high Mo austenitic stainless steel(00Cr20Nil8Mo6CuN)during hot deformation have been studied by using Formaster-Presshot working simulator. The hot deformation equation, as well as the relationship between peakstrain, peak stress and Zener-Hollman parameter, together with the deformation activationenergy have been resulted through the experiments.     

LOW CYCLE FATIGUE OF Cr-Mn-N STAINLESS STEEL

An investigation was conducted to examine the low cycle symmetric push-pull fatiguebehaviour of the Cr-Mn-N dual-phase stainless steel.Two groups of specimens,A and B,were used,they were solution treated at 1050 and 1250℃,respectively.The.fatigue life ofgroup A is almost twice as long as that of group B under the same total strain amplitude.Theenergy loss during the fatigue tests and the mophology of the fracture surfaces have been stu-died and discussed.     

4Cr14Ni14W2Mo钢氮化层剥落的研究

Unthank等人曾指出,含Cr高的奥氏体不锈钢在600～800℃氮化时,将沿晶界形成大量的CrN,并可能导致沿晶开裂,造成氮化层剥落.Kindlimann和Ansell认为,氮化表面上Fe或Ni-Fe的氮化物增到一定厚度时将产生“白亮层”,冷却时可能剥落。高濑孝夫在讨论氮化温度对18-8钢氮化层脆性影响时指出,低温氮化易出现氮化层剥落。本工作通过氮化前对试样作适当的预先热处理找到了解决氮化层剥落的方法,并探明了氮化层剥落的原因。     

粒状贝氏体组织的疲劳性能

本文研究了粒状贝氏体组织的低周疲劳性能、冲击疲劳性能及旋转弯曲疲劳性能.结果表明:在等抗拉强度下,粒状贝氏体的低周疲劳性能与冲击疲劳性能均优于回火马氏体组织.且随粒状贝氏体含量增加,冲击疲劳寿命相应提高.粒状贝氏体中的(M-A)岛对疲劳裂纹扩展有阻碍作用,对提高疲劳寿命有利.在等强度下,粒状贝氏体的旋转弯曲疲劳性能和回火马氏体组织相当,疲劳极限(Sf)与屈服强度(σy)和断裂强度(S_K)的关系为: S_f=4.651+0.1411(σ_y+S_K)     

INFLUENCE OF RARE-EARTH ELEMENTS ON THERMAL STABILITY OF PdSi_(16.5)GLASS

The influence of rare-earth elements,La,Ce,Pr,Nd,Sm,Eu,Gd,Dy,Ho,Er and Yb onthe thermal stability of PdSi_(16.5) glass was studied systematically by means of DSC.Allrare-earth elements,especially heavy ones,increase obviously the thermal stabilityparameters,including T_θ(T_g ,T_x ,T_g),T_(rg) and ΔE etc.The crystallization temperaturesT_(p1) and T_(p2) increase linearly with the lanthanide constriction increasing,but Eu shows ananomalous influence:Pd-Si-Eu metallic glass possesses the highest thermal stability and thelowest concentration limit of glass forming among Pd-Si-R glasses.     

超高强度钢疲劳塑性区内的应变诱发马氏体相变

对一种低碳马氏体型超高强度钢疲劳断口薄膜试样的电子衍射分析表明,疲劳塑性区内的残余奥氏体在交变应力的作用下转变为马氏体.本文就这种应变诱发相变对疲劳性能的作用机理进行了分析讨论.