高氮奥氏体不锈钢研究进展

目前高氮钢研究的主要热点是高氮不锈钢,而高氮奥氏体不锈钢的应用前景最被看好.综述近年来国内外高氮奥氏体不锈钢的研究现状,包括氮在奥氏体不锈钢中的作用机理;高氮奥氏体不锈钢的试制;高含量氮对奥氏体不锈钢力学性能、耐蚀性能和组织稳定性的影响以及对高氮不锈钢应用前景的展望.     

氮对冷变形高氮奥氏体不锈钢微观结构的作用

利用透射电镜(TEM)对氮含量为0.66%和1.2%的高氮奥氏体不锈钢的冷变形微观结构进行了对比研究.结果表明,氮含量的增加提高了材料的层错能,强烈促进位错的平面滑移.冷变形过程中不断形成机械孪晶,机械孪晶随变形量的增加而减小,在60%变形量时只有几百纳米长.运用扩展位错和短程有序理论对氮的作用机理的分析表明,氮合金化引起的短程有序是促进位错平面滑移、提高材料加工硬化能力的主要因素,低层错能引起的位错扩展也有重要作用.     

高氮奥氏体不锈钢锻件的制造

本文介绍奥氏体Cr-Ni-Mn-N钢压力加工时热力规范的研究。按此规范加工,能使轴类、套筒、护环等锻件的锻造工艺过程合理化,还可用3.2～32.5t的多元合金钢锭制得合格的毛坯件。     

N含量对高氮CrMnMo奥氏体不锈钢组织和性能的影响

以18Cr14Mn3Mo钢为基本成分,设计并冶炼了氮含量为0.008%~0.77%的高氮CrMnMo奥氏体不锈钢。通过力学性能测试、组织观察、扫描电镜观察等方法,研究了N含量对其硬度、耐刻划性、塑性、强度等的影响。结果表明,N含量为0.42%及以下时,组织为双相,存在着一定量的铁素体,铁素体的存在使材料的塑性和韧性都较差。N含量0.77%试验钢的硬度最高,为273 HV0.5;耐刻划性能也最佳。0.59%N试验钢的塑性和韧性最好,断面收缩率和冲击吸收能量分别为79%和422 J。综合认为高氮CrMnMo奥氏体不锈钢的最佳N含量为0.77%。     

高氮奥氏体不锈钢1Cr22Mn15N热影响区组织特征

高氮奥氏体不锈钢(高氮钢)是利用氮代替镍进行合金化的一种合金结构钢,其焊接技术将关系着此种钢的研制开发.作者对高氮钢焊接热影响区(HAZ)的组织和硬度进行了研究.结果表明,高氮钢焊接热影响区组织为奥氏体和δ- 铁素体.随着焊接冷却速度的增大,HAZ中δ- 铁素体的总量越多;随着焊接峰值温度停留时间的增加,HAZ中δ-铁素体的总量越多.在合适的焊接条件下,HAZ硬度高于母材,HAZ不存在软化区.     

冷变形对高氮奥氏体不锈钢组织与力学行为的影响

通过对氮含量为1.2%的高氮奥氏体不锈钢施加不同变形量的压缩变形,研究了冷变形对高氮钢的组织和力学行为的影响.结果表明,高氮钢在最高变形量达到56%时的冷变形过程中未发现有α'马氏体形成.高氮钢在变形初期孪晶和滑移共同参与变形,孪晶对滑移有强烈的阻碍作用.随变形量的增加,孪晶受到滑移线的切割,孪晶界不再清晰.高氮钢的加工硬化指数随变形量增加而降低.当冷变形至56%时,高氮钢的屈服强度提高了约2倍,抗拉强度提高了约1倍,分别达到1645 MPa和1870 MPa.对比分析氮在几种奥氏体不锈钢中的作用表明,氮通过短程有序排列的方式阻止位错的滑移,提高了高氮钢的加工硬化能力.     

镍对铜/不锈钢GTAW接头导电性及腐蚀性能的影响

针对新型铜/不锈钢单缝直焊型电解铜永久阴极板焊接接头的特殊要求,采用S201,S231和CuNi-7三种不同Ni含量的焊丝对T2紫铜与316L不锈钢进行GTAW焊,并对接头微观组织、成分、电导率和耐腐蚀性进行了分析.结果表明,三种不同Ni含量的焊丝所得焊缝界面清晰、无明显的宏观焊缝缺陷,但Ni含量的增加会对焊缝表面成形有一定影响;Ni含量低时会使钢侧焊缝中产生少量微裂纹,而随着Ni含量的增加焊缝中条状和块状Ni-Cr-Fe相随之增加;随着焊缝中Ni含量的增加,铜/不锈钢接头的电导率有所下降,这与焊缝中存在的Ni-Cr-Fe相数量成反比;铜/钢接头中Ni含量的增加可较为明显地提高铜/钢接头在酸性条件下的耐腐蚀性能.     

固溶时效对节镍型高氮奥氏体不锈钢组织的影响

对热轧态节镍型高氮奥氏体不锈钢进行固溶及时效处理,利用光学显微镜、电子背散射衍射,结合相图系统分析该材料固溶处理及时效后组织变化规律。结果表明,1050 ℃固溶处理后,试验钢基体为奥氏体,存在少量的铁素体,奥氏体晶粒形状偏等轴,晶粒内部存在大量孪晶。时效后,析出相主要为Cr₂N、CrN、Cr₂₃C₆。在时效时间为5 h不变的条件下,温度由650 ℃升高至800 ℃,碳化物及氮化物数量呈现先增长后降低的趋势,在750 ℃时数量最多。而在750 ℃时效5~10 h范围内,随着时效时间的增加,析出相数量变化不大。析出相的析出过程为:先在晶界交叉处析出胞状析出物,随时间的延长,在晶界逐渐析出条状析出物,在晶内开始出现并逐渐长大,最终形成类珠光体的片层状析出。     

Electrochemical corrosion behavior and microstructural characteristics of electron beam welded UNS S32205 duplex stainless steel

Different electrochemical techniques were used to study the corrosion behavior of UNS S32205 duplex stainless steel (DSS) welded autogenously using a single-pass by electron beam welding process, supplemented by microstructural characterization. Furthermore, a comparative study was also performed between multipass gas tungsten arc (GTA)-welded and EB-welded DSS for their microstructure and corrosion behavior. The differences in weld thermal cycle and chemical composition influenced the fusion zone microstructure of both the welds and eventually their corrosion properties. The general corrosion resistance of the EB weld was lower than the base metal and higher than the GTA weld despite its weld zone being characterized by a relatively unbalanced phase ratio (α/γ) in comparison to the GTA weld. However, the EB weld showed relatively higher susceptibility to pitting corrosion than the base metal and GTA weld due to its poor repassivation characteristics and poor resistance to pit growth.     

Thermodynamic study on welding wire design of high nitrogen austenitic stainless steel

Based on thermodynamic calculations, the effect of pressure and alloying elements on the nitrogen content, solidification mode, and welding characteristics were investigated in this study. By increasing the partial pressure of N_2, the nitrogen content in the weld pool increased dramatically, and the γ zone was enlarged. The nitrogen content increased as alloying elements such as Cr and Mn were added to the molten steel. The δ zone with high temperature treatment was compressed by adding Ni. These alloying elements play important roles in the formation of the single γ region at the temperature of 298 K. With proper Mn addition, the phase area of γ was extended and became more stable, and the "ferrite trap" was also avoided. Two kinds of welding wires with different nitrogen contents were developed and corresponding MIG welding experiments were performed. As the nitrogen content in wire was higher than that in the base metal, severe blowhole defects and mixture microstructure of δ and γ developed.     

低镍含氮奥氏体不锈钢激光-电弧焊电弧特性及组织性能

采用100％Ar2,98％Ar+2％N2,92％Ar+8％N2,85％Ar+15％N2四种混合比例的保护气体对08Cr19MnNi3Cu2N低镍含氮奥氏体不锈钢进行激光-脉冲MAG电弧复合焊接,研究保护气体中氮气比例对焊缝中气孔数量、焊缝熔深和熔宽、电弧形态、微观组织及铁素体含量等影响机制.结果表明,随着保护气体中氮气...     

高氮无镍奥氏体不锈钢耐蚀性的研究

以常压下冶炼的高氮无镍奥氏体不锈钢为材料,经1150℃强烈塑性变形,轧制成2 mm厚的板材,将热轧后的板材进行1100℃、保温10 h、水淬的固溶处理。通过酸浸试验、极化曲线测试和盐雾腐蚀试验,并与1Cr18N i9Ti钢的耐蚀性进行比较。结果表明,冶炼高氮无镍奥氏体不锈钢具有优异的耐腐蚀性能。     

Mechanical and corrosion properties of 445J2 ultra pure ferritic stainless steel joint

The microstructure, mechanical and corrosion resistance properties of 445J2 ultra pure ferritic stainless steel thin plate joints conducted by the pulsed current gas tungsten arc welding (PCGTAW) were discussed in this paper. In order to avoid weld defects, the appropriate welding process was adjusted. The joints were subjected to optical microscopy, transverse static tensile, plastic deformation, intergranular corrosion and electrochemistry corrosion tests. The results indicated that the weld zone (WZ) is characterized with columnar grains and equiaxed grains and the heat-affected zone (HAZ) shows coarse ferrite grains due to the rapid solidification of thin plate welding. The PCGTAW joint exhibited acceptable mechanical properties and equivalent corrosion resistance properties as the base metal.     

氮含量对无镍含钼奥氏体不锈钢相变的影响

以Cr18 Mn14 Mo3无镍含钼不锈钢为基本成分,设计并冶炼了电渣重熔锭实测氮含量为0.008％～0.770％的4炉高氮CrMnMo奥氏体不锈钢(氮含量设计范围为0.004％～0.850％),对各试验钢的平衡相转变进行了热力学计算,对试验钢的显微组织形貌进行了观察.结果表明:试验钢的氮含量在0.40％到0.85％区...