超细晶粒钢及其焊接性

介绍了超细晶粒钢的特点,针对这些特点,讨论了超细晶粒钢的焊接性,其中包括HAZ性能、焊缝性能、HAZ和焊缝的裂纹倾向等。     

Laser beam machining—A review

Laser beam machining (LBM) is one of the most widely used thermal energy based non-contact type advance machining process which can be applied for almost whole range of materials. Laser beam is focussed for melting and vaporizing the unwanted material from the parent material. It is suitable for geometrically complex profile cutting and making miniature holes in sheetmetal. Among various type of lasers used for machining in industries, CO₂ and Nd:YAG lasers are most established. In recent years, researchers have explored a number of ways to improve the LBM process performance by analysing the different factors that affect the quality characteristics. The experimental and theoretical studies show that process performance can be improved considerably by proper selection of laser parameters, material parameters and operating parameters. This paper reviews the research work carried out so far in the area of LBM of different materials and shapes. It reports about the experimental and theoretical studies of LBM to improve the process performance. Several modelling and optimization techniques for the determination of optimum laser beam cutting condition have been critically examined. The last part of this paper discusses the LBM developments and outlines the trend for future research.     

Weldability Aspects of a Newly Developed Duplex Stainless Steel LDX 2101

Duplex grades have, due to balanced chemical compositions of both filler and base metals, a weldability that allows for successful welding using a majority of the technically relevant techniques of today. In order to fulfil the performance requirements several aspects must be considered. In the heat affected zone (HAZ) the austenite reformation must be reasonably high and in the weld metal the microstructure must be stable so that e.g. high productivity welding and multi‐pass welding are possible, without precipitation of detrimental phases in previous passes. This paper addresses the effect of alloying elements and thermal cycles on phase balance in the high temperature HAZ (HTHAZ) of the newly developed lean duplex grade LDX 2101 (EN 1.4162, UNS S32101). Bead‐on‐plate welds and simulated weld structures have been produced and investigated using metallography, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results are analysed using the thermodynamic database Thermo‐Calc and a model for phase transformation based on a paraequilibrium assumption for ferrite‐austenite transformation. In the temperature region outside the paraequilibrium domain, growth controlled by diffusion of substitutional elements was considered. The analysis follows a model by Cahn regarding grain boundary nucleated growth and the Hillert‐Engberg model on kinetics of spherical and planar growth.     

角拘束对提高15MnMoVNRe钢焊接近缝区韧性的有利作用

本文用角拘束方法来改善15MnMoVNRe 钢近缝区的韧性,研究结果证明,从低温至室温拘束态的 Charpy-V 冲击功比非拘束态的均提高了20%以上,该结果是由于拘束提高了贝氏体开始相变的温度,从而使近缝区(M-A)组织的形态和精细结构发生变化所致。     

Effects of weld thermal cycles and post-welding tempering on second phase particles in 2·25Cr–1Mo–0·25V steels

Abstract

The solution and precipitation behaviours of second phase particles in the heat affected zone of 2·25Cr–1Mo–0·25V steels were investigated using a Gleeble-3500 thermal simulator and A-TEM. The results show that the mean size and the dimensional range of the second phase particles undergoing one weld thermal cycle decrease to 37·3 and 100 nm respectively. With increasing the number of weld thermal cycle and decreasing peak temperature of the second weld thermal cycles, the number of the precipitates increases. For the typical carbonitride formed in one and two weld thermal cycle, the composition of its centre is rich in titanium and the edge is rich in niobium and vanadium. In addition, after going through two weld thermal cycle, many strip particles are found in the bainitic ferrite laths and the composition is rich in niobium. After going through post-welding tempering, the particle dimensional range is about 200–300 nm and its shape became regular. The number of precipitate increases with increasing tempering holding time. The precipitates distribute along the grain boundary are rich in chromium, vanadium, iron and manganese.     

微合金非调质40MnV（Ti）钢焊接性研究

用斜Ｙ型坡口焊接裂纹试验，热拉伸试验，模拟热循环试验，焊接接头试验等方面，研究了４０ＭｎＶ（Ｔｉ）微合金非调质钢的焊接性。试验结果表明，４０ＭｎＶ（Ｔｉ０钢具有抗冷裂性和抗液化裂纹的能力，ＨＡＺ没有明显的脆化倾向，焊接接头与母材相比具有较高的强度和韧性。     

X80管线钢焊接热影响区软化问题研究

为了提高管线钢焊接热影响区组织性能,控制热影响区软化问题,分析了当前超低碳微合金X80直缝埋弧焊管焊接热影响区的软化现象,以及热影响区软化导致的弯曲开裂等质量问题。采用焊接热模拟及批量生产检验数据统计分析等方法,研究了影响X80管线钢焊接热影响区软化的因素。研究结果表明,母材合金元素、焊接热输入、母材强度以及三者之间的匹配是影响焊接热影响区软化的关键因素。指出,母材合金设计应考虑焊后热影响区的强度,母材强度应与热影响区强度相匹配。     

快速加热过程中Fe-40Ni-Ti合金的晶粒长大行为

利用热模拟技术、金相观察及定量统计,通过分析Fe-40Ni-Ti合金快速升温过程中试样不同部位的晶粒长大规律,模拟研究了焊接过程中奥氏体晶粒的长大行为.结果表明:温度最高的中心线附近晶粒长大显著,5 s内温度达到1350℃时,其尺寸达到了180 μm;而距离中心线4 mm处的热影响区及母材(试样端部)晶粒变化不大,在80 μm左右.金相观察发现TiN颗粒对晶界迁移产生了明显的阻碍作用.     

石油储罐钢焊接热影响区模拟研究

采用焊接热模拟技术,研究不同焊接热输入条件下焊接热循环对石油储罐钢焊接热影响区粗晶区(CGHAZ)的组织和性能的影响.结果表明:实验钢在80～100kJ/cm的大热输入下,热影响区仍能够保持良好的低温韧性;随着焊接热输入的增加,实验钢CGHAZ组织变粗大,低温冲击功下降;钢中弥散分布着大量细小TiN粒子,在焊接热循环中...     

西气东输二线工程用X80螺旋埋弧焊管热影响区性能分析

对西气东输二线工程用X80级φ1219 mm×18.4 mm螺旋埋弧焊管热影响区夏比冲击韧性和维氏硬度进行了统计分析.结果表明:X80螺旋埋弧焊管热影响区具有优良的力学性能,不同钢厂产品之间性能差异较小;热影响区夏比冲击功低于管体母材130 J;硬度低于母材15～24 HV10,存在明显的热影响区"软化"现象.随着钢级...