Microstructural developments and precipitate transformation during transient liquid-phase bonding of a duplex stainless steel

Effect of holding time on microstructural developments and transformation of precipitates formed at the interface during transient liquid-phase bonding of a duplex stainless steel using a Ni-based amorphous insert alloy was studied. The experimental results reveal that the microstructure of the adjacent base metal varies clearly as a function of holding time. The migration of Cr and Ni elements and the → transformation seem to play relevant roles in this microstructure evolution. The scanning electron microscopy (SEM) and electron prob X-ray microanalysis (EPMA) results indicate the transformation of BN→BN and (N, Mo) boride→BN at the interface with the holding time of 60-1 800 s. N content changes with holding time increasing at locations at the interface might be a controlling factor contributing to this transformation.

Development of ferritic stainless steel products at Baosteel

Ferritic stainless steel （FSS） for various applications was developed on the basis of Thermo-calc simulation. Alloy design, precipitate analysis and processing parameters optimization were carried out on the basis of the simulation results according to the technical requirements of the applications. These developed products have outstanding properties, such as mechanical strength, ductility, formability, weldability and corrosion resistance. Baosteel has formed a series of FSS products which will increase the profit of the company and enhance the product variety of stainless steel.

Recent developments in stainless steels:austenitic,ferritic,duplex

A review is given concerning some of the recent industrial developments of stainless steels. In austenitic stainless steels,two different directions of alloy development are noticeable:low nickel austenitic stainless steels and high nitrogen stainless steels.In these two cases the aims are different,particularly in terms of strength,but the philosophy of alloy development and the scientific approaches are very similar and they all revolve about the role of nitrogen as an alloying element and how this affects strength,ductility and corrosion resistance. There is now a broad and useful basis of information as to how nitrogen affects solid solution hardening,grain boundary hardening and work hardening and how to make use of these effects in developing materials required by the world market. In the field of corrosion resistance,ferritic,duplex and austenitic stainless steels compete with each other and now there is a growing body of information concerning the relative corrosion resistance based on laboratory data. However,for practical applications and for alloy selection,more than just laboratory data are needed,and thus,the first results are presented here of a many years comparison of the corrosion resistance of 24 commercial stainless steels exposed to corrosion in outdoors marine atmosphere.Hope is expressed to involve in the near future even more steels from a wider range of manufacturers in such corrosion studies.This might help consumers in appropriate alloy selection.It might also help steel makers in developing appropriate stainless steel grades.

The sustainability of valuable metals—recycling of residues from stainless steel production

The European stainless steel producers generate 20 -30 kg dust per ton of produced stainless steel.The dust formed during various stages of the production process contains valuable metals such as Cr,Ni and Mo.In general this dust is considered as a hazardous waste.If not taken care of the dust will be an environmental risk causing potential problems such as leaching of heavy metals into groundwater and pollution of land and air.By applying techniques for recycling the dust the problem is minimized and valuable metals are recovered and re-used as raw material in the steel making process,leading to a significant reduction of the consumption of natural resources to decelerate the climate change and ensure a sustainable development.One of the business segments of Befesa Zinc S.L.U.,a subsidiary company of Abengoa,is the recycling of dusts and other residues containing nickel,chromium and molybdenum from the stainless steel industry.The technologies applied are submerged arc reduction smelting(Befesa Valera S.A.S.,Gravelines,France) and plasma reduction smelting(Befesa ScanDust AB,Landskrona,Sweden).Stainless steel plant dusts,mill scale and other residues are delivered in closed containers and big bags by ship,rail or truck and stored.After a preparation of the residues and charging into the pyrometallurgical furnace,the metal compounds contained in the charge are reduced to metals in the presence of the carbon added.At Befesa ScanDust,the regularly tapped liquid metal is cast in the form of granules via the Granshot^(?) granulation process.The granulated product has many advantages such as excellent preheating properties and fast melting when added to a metallurgical process.The granules size and shape also makes it very suitable to handle with most raw material handling systems.By granulating the so-called alloyed pig iron(API) a high metallic yield is achieved ensuring maximum recovery of metal and less new dust generation compared to a crushed material.The granules are redelivered to the stainless steel producers or sold on the open market.

The process development and product application of Tisco DSS

DSS have high strength,high corrosion resistance and good welding properties.Comparing with the same corrosion resistance level austenitic stainless steel,DSS decrease largely Ni content and realize the thinning of thickness design to perfectly optimize properties and decrease costs.Now DSS have been widely used in many fields such as petroleum,chemical industry,paper production,shipbuilding,nuclear power, seawater desalting,vacuum salt production and architecture.Tisco have began the process development and product application research of DSS products from last century and gradually solved a lot of technical problems such as AOD nitrogen alloying control of various content DSS,high temperature deformation mechanism of thermal process,large deformation hot rolling process of coils,the effect of bad phase precipitated during hot treatment process on properties and high efficiency pickling of high Cr/Mo content DSS plates.The various alloy content DSS plates and wide cold rolling coils(3Re60,S32101,S32304, S31803,S32205,S32750 and SUS329J4L) were successfully developed and used in national important constructions,key industries and abroad projects.

Investigation of the Microstructure of Rolled Semi-Solid Steel

In this paper, spring steel-60Si2Mn and stainless steel-1Cr18Ni9Ti were rolled one pass in the semi-solid state. The microstructural evolution during rolling of the steels with different solid fraction was investigated. The experimental results showed that the manner of liquid and solid phases flowing and deforming was different. During rolling, most of solid phases remained in the center of the rolled specimens, while liquid phase flowed to the edge, which resulted in the macrosegregation of liquid and solid phases. Only the amount of solid fraction reached a certain value, were the solid phases deformed and flattened.

中碳27SiMn弹簧用板材开发

文章介绍了弹簧钢板27SiMn新产品生产工艺流程及相关的工艺参数。通过合理的轧后冷却参数设定,得到了产品需要的组织,该组织保证了产品的力学性能。用户使用情况表明,充分利用包钢现有的装备,采用合理的工艺参数,在原料及铁水都满足要求的情况下,生产出的27SiMn弹簧钢板性能良好,其抗拉强度不小于800 MPa,延伸率不小于19%。此外,加热炉的气氛对含硅中碳钢的表面脱碳层有重要影响,还原性气氛和加热炉内微正压操作使27SiMn弹簧钢板表面脱碳层只有国标GB/T 1222—2016要求的24%。

沉淀硬化不锈钢弹簧脆性断裂原因

某沉淀硬化不锈钢弹簧发生脆性断裂。采用宏观观察、氢元素含量测试、金相检验、硬度测试、扫描电镜及能谱分析等方法分析了该弹簧断裂的原因。结果表明:在进行表面钝化处理过程中,弹簧发生了渗氢现象,经除氢处理后弹簧仍含有少量的氢元素,在应力作用下,弹簧萌生了氢致脆性微裂纹,裂纹不断扩展,最终导致弹簧发生过载断裂。

某航空密封件波形弹簧模态分析

该项目以0Cr17Ni7Al不锈钢波形弹簧为研究对象,利用CATIA软件进行建模并导入ABAQUS软件中进行有限元分析,获得其0~12阶模态特性。基于实际压缩高度分析受力情况的波形弹簧自振频率,并对2种自由态以及工作状态的弹簧仿真结果进行对比,得到固有频率的数据以及振形图。为不同情况下弹簧种类的选择提供一定参考。

不锈钢管专用抛丸机的开发及应用

介绍了一种不锈钢管专用抛丸机,对设备的主要参数、工作原理、主要部件的功能以及适用范围进行了详细的介绍。本设备用于不锈钢外表面的清理,整机采用PLC控制解决了现在市面上设备存在的自动化程度低、人工劳动强度大、清理效果差且不能满足环保要求的问题,提高了设备的清理效率,从而有助于促进行业的发展。

铜与不锈钢焊接技术与工艺研究现状

铜与不锈钢的合金结构件广泛应用于石油化学、空调冷凝、航空航天和汽车零部件等中高端工业领域,存在着广阔地展现出极高的实用价值和应用潜力。由于铜与不锈钢物理化学性质差异较大,使得两者之间的焊接相当困难,文章通过分析铜与不锈钢的焊接性,综述了各种焊接方法及其原理,分析了各种焊接缺陷以及解决办法,并指出当前领域内的研究热点与难点。同时,文章还将展望铜与不锈钢异种金属焊接技术的未来发展趋势,以期推动该领域的持续进步。

不锈钢弹簧蠕变与应力松弛行为研究

为了研究电力高压开关柜触头抱紧不锈钢弹簧的蠕变与应力松弛行为,建立不锈钢材料的蠕变本构方程,并建立不锈钢弹簧的有限元模型,对蠕变与应力松弛行为进行模拟,分析温度和丝径对不锈钢弹簧蠕变行为的影响。结果表明,环境温度越高,不锈钢弹簧的蠕变应变越大;不锈钢弹簧服役温度从25℃提高至320℃,24 h蠕变应变增大5倍;丝径增大,不锈钢弹簧的应力减小,蠕变应变也随之减小;丝径从0.8 mm增大至1.1 mm,24 h蠕变应变从0.8%减小至0.09%。

60Si2MnA弹簧钢板开发

文章介绍了弹簧钢板60Si2MnA的生产工艺流程以及相应的工艺参数,并且通过相应的冷却工艺(4~9℃/s)控制,可以得到产品需要的组织,该组织保证了产品的力学性能。结果表明,以包钢现有的装备及工艺,在合适的铁水条件及其他原料条件下,选择恰当的工艺参数,可以生产出抗拉强度不低于1050 MPa、延伸率不小于13%的60Si2MnA弹簧钢板。另外,通过控制加热炉的气氛,使高碳钢60Si2MnA钢表面脱碳层厚度控制较好,仅为国标GB/T 1222—2016要求的18%。

不锈钢中厚板成材率提升的综合策略制定及应用探索

为提高中厚板成材率,基于不锈钢中厚板多规格、小批量的特点,根据自身生产实际,开发自动化组板功能对生产订单进行集约生产,同时配合轧制过程的平面形状控制等技术,对生产端生产过程进行控制优化,并重点强化同财务端及订货端的需求交互,最终完成了以财务指标为目标导向的成材率降本综合策略的制定。

高氮低镍奥氏体不锈钢的研究进展

高氮低镍奥氏体不锈钢是一种以氮代镍来获得稳定奥氏体组织的新钢种,它不但可以提高不锈钢的综合性能、节约镍资源,而且可以解决含镍较高的不锈钢用于人体时造成的镍过敏问题,在生物医学领域应用潜力巨大。综述了高氮低镍奥氏体不锈钢的发展历史和现状、不锈钢中氮的作用及高氮钢的主要制备工艺。

医用不锈钢的发展及展望

在各类医用金属材料中,医用不锈钢因其优良的综合性能在临床及医疗领域得到了广泛应用。概述了医用不锈钢的发展历程,指出了目前存在的问题,并总结了近年新型医用不锈钢的研究开发状况。最后,展望了医用不锈钢今后的发展。

高氮奥氏体不锈钢的研究进展

高氮奥氏体不锈钢由于具有强度高、韧性好、无磁、耐腐蚀性能佳及晶间腐蚀敏感性低等诸多独特优点而得到越来越广泛的应用,但基础理论和制造技术方面的研究仍相对落后。文中分析了高氮奥氏体不锈钢的研发历程和冶金理论现状,综述了高氮奥氏体不锈钢的钢种、成分、制造工艺和力学性能,以及该钢的发展与展望。

抗菌不锈钢材料及其发展现状

综述了各种抗菌不锈钢材料(包括加铜和加银的抗菌不锈钢、表面涂层抗菌不锈钢、抗菌复合不锈钢板)的抗菌机理、特点,应用和开发现状。在普通不锈钢内添加一定量的抗菌金属元素Cu,Ag,Zn等,控制铸造、锻压、轧制以及热处理过程,使抗菌金属元素在不锈钢基体内以一定的大小、形态,均匀弥散地析出,并保证析出相的体积百分比,在不降低普通不锈钢的力学性能和抗腐蚀性能的情况下,赋予其优异的抗菌性能。

双相不锈钢的研究进展及其应用

简要地介绍了国内外铁素体+奥氏体双相不锈钢的发展史及近年来研究的进展情况,综述了国内外双相不锈钢的主要种类、力学性能、腐蚀性能等特点,介绍了国外研制开发的几种新型双相不锈钢及其在工业上的一些主要应用,并初步探讨了双相不锈钢在武器装备上应用的必要性和应用前景。

不锈钢着色法研究的新进展

概述了国内外不锈钢着色的新处理方法和原理 ,分析了各种方法的特点及利弊 ,探讨了不锈钢着色的发展前景。