Effects of Niobium Addition on Microstructures and Formability in Si‐Al‐Mn TRIP Cold‐rolled Steels

The effects of Nb addition on microstructures and formability in Si‐Al‐Mn TRIP cold‐rolled steels were investigated. These steels were intercritical annealed at 770 °C for 5 min, and isothermally treated at 400 °C for 3 min. Microstructural observation, tensile tests and forming limit diagram (FLD) tests were conducted, and the changes of retained austenite volume fraction as a function of tensile strain were measured by using an X‐ray diffractometer. The results showed that Nb addition makes grain size refined, the volume fraction of ferrite increase and that of bainite decrease, however, obviously it does not affect the volume fraction and carbon content of retained austenite. The Nb addition increased the stability of retained austenite owing to grain refinement. With Nb addition, increase in strength, ductility, strain hardening exponent and formability could be achieved simultaneously. These findings indicate that Nb addition can be a new direction of microalloying design for the low carbon TRIP steels with excellent formability and high stability of retained austenite.     

Effects of TiN and AlN Nanoparticles in Hot Deformation of Austenite in Steels

Recrystallisation kinetics of two low‐carbon steels, of which one with Ti and the other with Al as precipitate‐forming elements was studied by means of hot torsion tests. The mean size of TiN and AlN particles that precipitate during hot deformation was analysed by transmission electron microscopy (TEM). These results, along with the determination of the activation energy, the precipitated volume fraction and the diffusion coefficients of Ti, Al and N in austenite explain the ineffectiveness of these particles to inhibit the static recrystallisation.     

Fe-C-Cr-V合金的价电子结构对奥氏体等温转变的影响

本文用余瑞璜先生的“固体与分子经验电子理论”计算了工业牌号的50、50Cr、50CrV钢奥氏体的价电子结构,从原子杂化状态、共价键力大小的价电子深度,讨论了合金相的价电子结构对过冷奥氏体等温转变的影响,并结合60Si_2Mn钢奥氏体的价电子结构,讨论了碳化物形成元素Cr、V和非碳化物形成元素Si在相变中的行为与作用。键距差(BLD)分析的基础数据由余瑞璜先生提供。     

Microstructure and stress corrosion cracking in simulated heat-affected zones of duplex stainless steels

The effects of nitrogen content and the cooling rate on the reformation of austenite in the Gleeble simulated heat-affected zone (HAZ) of 2205 duplex stainless steels (DSSs) were investigated. The variation of stress corrosion cracking (SCC) behavior in the HAZ of 40 wt% CaCl₂ solution at 100 °C was also studied. Grain boundary austenite (GBA), Widmanstatten austenite (WA), intergranular austenite (IGA) and partially transformed austenite (PTA) were present in the HAZ. The types and amounts of these reformed austenites varied with the cooling rate and nitrogen content in the DSS. U-bend tests revealed that pitting corrosion and selective dissolution might assist the crack initiation, while the types and amounts of reformed austenite in the HAZ affected the mode of crack propagation. The presence of GBA was found to promote the occurrence of intergranular stress corrosion cracking. WA, IGA and PTA were found to exhibit a beneficial effect on SCC resistance by deviating the crack propagation path.     

测定钢中残余奥氏体量的磁学方法的研究

本文以GCr_(15)和W_(18)Cr_4V钢作材料,用磁学法(电流换向法)测定钢中残余奥氏体量,提出了一种碳化物修正的新公式,并为实现快速、恒等电流换向而采用了一种新方法。     

40CrMnSiMoVA钢马氏体区和贝氏体区等温淬火的组织与强韧性

本文研究了40CrMnSiMoVA 钢在马氏体区(190℃)和贝氏体区(300℃)等温淬火后的组织与强度、塑性、韧性、多次冲击疲劳性能及周期强度间的关系。探讨了其强韧化的机理,证明贝氏体区等温淬火后在综合力学性能上具有明显的优越性。     

钢的过冷奥氏体转变图（CCT）的计算机绘制

ＣＣＴ图是制定钢的热处理工艺的重要依据。本软件对所测数据进行分段抛物处理，实现了曲线的拟合，用ＢＡＳＩＣ语言设计出具有在半对数会标系下绘制ＣＣＴ图的软件，该软件再与ＡＵＴＯＣＡＤ联接，在ＣＡＤ软件支持下，自动绘出精确、实用、美观的ＣＣＴ图。     

室温予先形变对低碳钢氰化影响的探讨

研究了室温不同变形主不同的变形量对２０、２０Ｃｒ两种钢的氰化渗层浓度、显微组织及渗层Ｃ、Ｎ浓度、残余奥工体的影响。     

Martensite transformation induced by deformation and its phase electrochemical behavior for stainless steels AISI 304 and 316L

The martensite transformation induced by tensile elongation and its effect on the behavior or phase electrochemistry of AISI 304 and 316L in 3.5% NaCl solution were studied.The results show that the content of α′-martensite in stainless steel 304 increases with the true strain,As α′-martensite content increased.freee corrosion potential and pitting potential of stainless steel 304 in 3.5% NaCl solution appeared the change trend of a minimum.It was also found that pitting nucleated preferentially at the phase interfaces between martensite and austenits,There exsted apparent differnece between electrochemical properties of austenite and of martensite for stainless steel 304 and 316L in 3.5% NaCl solution.     

强韧性高铬铸铁磨球的研究与应用

本文通过研究高铬铸铁的结晶特性,在铸态铬屈氏体磨球的基础上,进一步优化设计材质,采用金属型群铸工艺,科学地控制铸态高温奥氏体的相转变温度,在铸态下使φ20～φ50磨球获得合金奥氏体,使φ60～φ100磨球获得合金贝氏体.在这两种强韧,性的基体上均匀分布着精细的 M_7C_3型共晶碳化物,经时效处理直接应用于工业生产.使用证明,这种奥、贝基体磨球强度高、韧性好、耐磨性能优良,球耗率为2.2～50g/t 水泥.