汽车排气系统用铁素体不锈钢的应用及腐蚀失效评价

最近几年,随着对全球环境问题的关注,汽车燃油的经济性和汽车尾气排放的等级化要求不断提高,铁素体不锈钢更多用于汽车排气系统零部件。铁素体不锈钢性能得到了明显改善,使铁素体不锈钢具有低的价格和良好性能,欧美及日本汽车几乎全部使用超纯铁素体不锈钢用于排气系统零部件制造。介绍了汽车排气系统的构成及对各部件常用不锈钢的性能要求、排气系统零部件的主要失效形式和所用不锈钢材料的腐蚀评价方法。     

宝钢汽车排气系统用铁素体不锈钢产品开发

最近几年,随着对全球环境问题的关注,各国都对汽车尾气排放要求给予高度重视以减低对环境的危害。随着汽车燃油的经济性和汽车尾气排放的等级化要求不断提高,排放标准变得更为严厉。因铁素体不锈钢具有良好的耐氧化性、低的热膨胀系数、高的抗腐蚀性能及更为经济的成本,铁素体不锈钢更多用于汽车排气系统零部件。欧美及日本汽车几乎全部使用超纯铁素体不锈钢用于排气系统零部件制造以满足汽车轻量化及严格的尾气排放要求。介绍了汽车排气系统的构成、各部件的性能要求及宝钢汽车用不锈钢的产品开发。     

汽车排气系统用409型铁素体不锈钢的开发研究

描述汽车排气系统的结构及其对材料的特殊要求,介绍不锈钢分公司409型铁素体不锈钢的开发过程.该钢具有良好的高温性能、成形性及耐腐蚀性,可以较好地满足汽车排气系统用钢的需求.     

汽车排气系统用不锈钢及焊管制造技术

铁素体不锈钢具有良好的耐氧化性、低的热膨胀系数、高的抗腐蚀性能以及更为经济的成本,使得铁素体不锈钢更多地用于汽车排气系统零部件。欧美及日本汽车全部使用不锈钢材料特别是铁素体不锈钢用于排气系统零部件制造以满足汽车轻量化及严格的尾气排放要求。其中,汽车排气系统中60%以上零件为管件。介绍了汽车排气系统的构成、常用不锈钢品种及各部件的性能要求,并阐述了汽车用不锈钢焊管的主要焊接加工方式。     

变形对汽车用铁素体不锈钢微观组织及抗氢性能的影响

铁素体不锈钢(FSS)具有良好的成形性能、低成本和耐腐蚀性能,被广泛应用于汽车制造等行业.本文通过对退火态、轧制20％、轧制40％的AISI430铁素体不锈钢进行4h的电化学充氢,研究了变形对汽车用AISI430铁素体不锈钢组织性能的影响和氢脆断裂机理.轧制态铁素体不锈钢具有较高的氢脆敏感性,氢对材料力学性能影响显著,...     

深拉延性优异的汽车燃油箱用铁素体不锈钢的开发

镀铅锡钢板广泛用于普通汽车燃油箱，但是环境法规越来越严，汽车生产厂家正在改变采用含铅材料和类似材料的做法。我们开发出兼备汽车燃油箱和燃料系统其它部件所要求的耐蚀性和成形性的一种新型铁素体不锈钢。与塑料燃油箱不同，铁素体不锈钢燃油箱没有燃油排放的危险，容易回收。新开发的深拉延性优异的18Cr-1．5Mo-Ti铁素体不锈钢还为燃油系统的其它应用方面提供了优越性。     

汽车排气系统高温端用B441铁素体不锈钢研制

为了开发满足排气系统高温端零件使用要求的不锈钢产品,在实验室研究了化学成分、热处理制度对B441不锈钢性能的影响.结果表明,稳定化元素Nb、Ti的添加对改善B441不锈钢的综合性能有利.生产试制结果表明,生产的B441铁素体不锈钢产品具有优良的常温力学性能和耐高温性能,能够满足汽车排气系统高温端使用要求.     

超纯铁素体不锈钢425组织性能研究与评价

425不锈钢是一种针对汽车排气系统冷端开发的资源节约型超纯铁素体不锈钢,其中铬元素的质量分数为15%,采用铌钛双元素进行碳、氮的稳定化控制。通过光学显微镜、扫描电子显微镜、万能电子试验机以及电化学工作站等,研究880~1 000 ℃退火后425不锈钢显微组织和拉伸性能的演变规律,并与409和439不锈钢进行成形性及耐腐蚀性能的对比研究。结果表明,退火温度为960 ℃时,425不锈钢具有最佳的显微组织和拉伸性能组合,其成形性能与439、409相当,点腐蚀速率略大于439、明显低于409,点蚀电位介于409和439之间。总体来说,超纯铁素体不锈钢425具有良好的塑性、成形性和耐腐蚀性能,是汽车排气系统冷端应用的理想材料。     

日新制钢汽车排气系统用耐热铁素体不锈钢的开发

为了减轻空气污染和缓解全球变暖,各个国家均出台了尾气排放标准,且限制标准越来越严格。在此背景下,多种技术已被应用以满足相关要求,如提高燃油燃烧率、催化效率,降低排气管热容量等。而这一系列措施均会导致汽车尾气的最高温度上升。近些年,汽车排气系统零件主要用铁素体不锈钢制作,因为铁素体不锈钢的热膨胀系数小,耐循环氧化和耐高温疲劳性能均优于奥氏体不锈钢。介绍了日新制钢新研发的汽车排气系统用耐热不锈钢,以及该钢种的研发现状和发展趋势。Nb、Mo、Cu在700℃时的固溶强化和析出强化对提高铁素体不锈钢的高温强度非常有效,而添加Nb、Mo、W主要是在900℃时起到固溶强化作用。Cr,Si和Mn可降低铁素体不锈钢(含14%Cr)在大气中950℃保温200h的氧化程度。特别是添加0.8%及以上的Mn可有效提高氧化皮的附着力。事实证明,日新制钢开发的NSSHR-1(14Cr-1Mn-0.9Si-Nb)和NSSHR-2(10Cr-0.9Si-Nb-Ti)铁素体不锈钢与441和439不锈钢相比,具有更高的耐热性和成形性。     

汽车尾气排放系统用不锈钢的现状及发展趋势

不锈钢最早是作为装饰材料用于汽车上，然而，近年来，汽车尾气排放系统中大量使用了不锈钢。这是因为不锈钢具有较好的高温性能和优良的耐蚀性，能满足社会对汽车尾气清洁排放的需要，并能减轻车身重量，从而节省燃油消耗。本文详细阐述了汽车尾气排放系统用材料的变更及未来发展趋势，同时还介绍了近年来开始用于摩托车尾气排放系统的不锈钢。     

Nb对0Cr11铁素体不锈钢组织和性能的影响

 铁素体不锈钢与奥氏体不锈钢相比具有成本低、热膨胀系数低和耐应力腐蚀等优点,所以被广泛应用到汽车排气系统、家用电器和建筑等领域。研究了不同的Nb含量对铁素体不锈钢显微组织和力学性能的影响。研究结果表明：Nb有细化晶粒的作用,随着Nb含量的增加,晶粒的平均尺寸减小;由于合金元素Nb和Ti的加入,形成了TiN、NbC 和 Fe2Nb析出相,其透射电镜观察结果与Thermal calc计算结果一致;材料的抗拉强度和显微硬度随着Nb含量的增加而增加,这是由于Nb的固溶强化和析出强化共同作用的结果。     

新型汽车排气系统用铁素体不锈钢的冷凝液腐蚀研究

 铁素体不锈钢中Cr元素对其耐腐蚀性能起着非常重要的作用。本文采用实验室冷凝液腐蚀实验方法,对一系列汽车排气系统用铁素体不锈钢在实验室模拟冷凝液中的腐蚀性能进行了研究。所有钢种经过10周期的实验室冷凝液腐蚀实验后,研究结果表明：Cr当量高于17%的铁素体不锈钢与含17%Cr的铁素体不锈钢耐实验室冷凝液腐蚀性能相当,且平均腐蚀失重量均小于6g/m2,平均最大腐蚀深度均小于0.03mm。在此实验结果的基础上,对新开发的439M型铁素体不锈钢和409L型铁素体不锈钢进一步开展5周期、10周期、20周期的实验室冷凝液腐蚀实验,并使用极值分析方法对三种周期冷凝液腐蚀实验后样品的最大点蚀深度进行统计分析,研究结果表明,新开发的439M型铁素体不锈钢的预测寿命是409L的1.6倍。     

Stainless Steels for Exhaust Lines

Exhaust lines of cars have been strongly evolving during the last decade to meet the various requirements of the automotive industry and the new environment regulations. This development tends to favour stainless steel grades to replace cast iron for the exhaust manifold and aluminized low carbon steel for pipes and mufflers. Among the various stainless steel grades, the proportion of ferritic grade increases for the hot part of the exhaust system as its price is lower and more stable than austenitic or refractory grades, and as it exhibits a better resistance to cyclic oxidation. A large and rapid development of stainless ferritic grades has been based on Ti and Nb stabilization. Adding niobium presents many advantages for corrosion resistance, deep‐drawability, and mainly creep resistance at high temperature. The paper is focused on stainless steel with 14 wt% chromium, stabilized with Nb. Intermetallic precipitation is studied after a 100 h holding time at different temperatures (sag tests). It is shown that, depending on the test temperature and on the chemical composition of the steel, Fe₂Nb or Fe₂Nb₃ intermetallic particles can precipitate, which affects the creep resistance: Fe₂Nb₃ being more stable at higher temperature. Some impacts on the alloy design dedicated to exhaust line application are presented as a conclusion of the study.     

Behaviour Model of Austenitic Stainless Steels for Automotive Structural Parts

One of the most important preoccupation of car manufacturers is to reduce emissions and hence to reduce weight of cars. One of the outstanding materials able to reduce weight while at the same time keeping the same crash absorption and hence safety, is austenitic steel. Austenitic stainless steels are used in crash relevant parts of cars. Moreover, designers can use their very good corrosion resistance and their well known surface aspect for structural visible parts like wheels, cross members, roof panels or tailgates. In this paper, stainless steels for automotive use are presented in detail. First, their chemical composition and tensile properties are explained. Then, a model for forming and crash behaviour is described. Using this model, stainless steels can be engineered into automotive parts and thus stainless steel can be considered as a workable and predictable material for the automotive industry.     

Development of heat-resistant ferritic stainless steels for exhaust lines at Nisshin Steel

Exhaust emission regulations of the automotive are enforced in each country to prevent air pollution and global warming,and the restriction standard tends to become severer.Various techniques such as the combustion improvement of gasoline,upgrades of the catalyst,and the thermal capacity decreases in the exhaust lines are adopted to suit the regulations,and these lead to an increase of the maximum temperature of the exhaust gas. Recently,ferritic stainless steels are mainly used to parts of exhaust lines,as their thermal expansion coefficient is small,and the cyclic oxidation resistance and the thermal fatigue property are better than austenitic stainless steels. This paper presents newly developed heat-resistant stainless steels from Nisshin Steel for exhaust lines usage,and describes the currents of the steel development that could be envisaged in the future.With regard to improving the high-temperature strength of ferritic stainless steels,the addition of Nb,Mo and Cu is effective in solution hardening and precipitation hardening at 700℃,while the addition of Nb,Mo and W is effective in mainly solution hardening at 900℃.The addition of Cr,Si and Mn suppress the breakaway oxidation in air at 950℃up to 200 h of ferritic stainless steels containing 14%Cr.Especially,the addition of 0.8%or higher Mn would effectively improve the adherence of oxide scale.It is confirmed that ferritic stainless steels,NSSHR-1(14Cr-lMn-0.9Si-Nb) and NSSHR-2(10Cr-0.9Si-Nb-Ti ),is having a superior heat resistance,formability and cost performance compared to conventional Type441 and Type439 respectively.     

高耐蚀深冲用不锈钢00Cr17MoTiCu的开发

本文采用电化学、盐雾试验、酸溶液中的耐蚀性试验等腐蚀试验方法,评价了Cr、Mo、Ti、Cu等元素的作用,同时采用力学试验和各种成型试验方法探讨了上述元素的影响。根据试验结果成功地开发了既具有可以和1Cr18Ni9Tj相媲美的不锈耐蚀性能;又具有Cr17型不锈钢美观、价廉等特征的新型深冲用不锈钢00Cr17MoTiCu。该新型不锈钢可广泛应用于食品加工、厨房设备、轻工纺织、建筑五金等行业。