冷镦钢质量控制技术

紧固件的加工通常以冷镦钢为原材料，冷镦钢的质量对紧固件加工过程和产品质量有着非常重要的影响。分析了影响冷镦钢质量的关键因素、冷镦开裂原因和压缩比对冷镦性能的影响，对国内外冷镦钢在显微组织性能等方面做了比较，最后探讨了冷镦钢未来发展方向。     

SWRCH35K冷镦钢开裂原因分析

冷镦钢主要用于常温下冷镦成型标准件,由于材料局部变形大,容易在产品表面造成开裂.为了改善冷镦钢的性能,提高冷镦产品的合格率,对SWRCH35K冷镦钢轧制的盘条在冷镦生产标准件时出现开裂的原因进行了研究.采用酸洗、金相检测、能谱分析等方法,分析SWRCH35K冷镦钢的表面质量、金相组织、晶粒度和非金属夹杂物.得出其冷镦开裂的原因主要是盘条存在表面折叠缺陷和铸坯中偏析裂纹,同时提出相应的改进措施.     

韶钢高一线轧制过程导致冷镦钢冷镦开裂的原因及控制措施

在韶钢高一线重点开发冷镦钢等高等级工业线材的背景下,针对冷镦钢冷镦过程中存在的冷镦开裂问题进行了研究,重点分析了由于轧制过程中造成的表面质量问题导致冷镦过程开裂的情况,指出了轧制过程中造成冷镦开裂的原因主要是由于料型出耳、折叠缺陷和轧制过程中的划伤缺陷,提出的工艺改进措施通过现场实践表明效果显著,大大改善了韶钢高一线存在的冷镦钢冷镦开裂质量问题,取得了显著的经济效益。     

SWRCH35K冷镦钢开裂原因分析与控制

分析了SWRCH35K冷镦钢在生产标准件过程中开裂的原因,认为盘条存在非金属夹杂物是造成冷镦钢开裂的主要原因。通过对转炉、精炼及连铸工序实施相应的改进措施,改善了SWRCH35K冷镦钢的性能,提高了冷镦产品的合格率。     

冷镦钢产品顶锻开裂的机理分析及应用

冷镦钢是用于制造螺栓、螺母、铆钉、插销等紧固件的一种重要功能材料，冷镦性能是材料性能的重要指标。冷镦钢在冷顶锻检验时，顶锻开裂的现象可以归纳为周面脆性开裂、塑性斜向开裂、断续纵向微裂、通长纵向开裂四类主要开裂现象。本文根据断裂力学理论，结合顶锻试样开裂的不同表现，对试样不同开裂情况进行了理论研究．分析了各种开裂现象的产生机理，并据此制定了生产过程中提高冷镦钢冷顶锻性能的相关措施。     

冷镦钢生产实践

通过对冷镦钢冶炼过程增碳，冷镦开裂原因的分析，经过对工艺的优化，产品性能达到了用户要求。     

低碳冷镦钢盘条冷镦开裂研究分析

针对低碳冷镦钢冷镦开裂问题,通过试样研究确定,元素含量、晶粒度大小、孔型及过钢通道状况等因素对冷镦性能至关重要。通过对元素含量、晶粒度控制及孔型轧制吨位、过钢通道优化,有效提高了冷镦性能稳定性。     

控轧过程中冷却速度对35 K钢盘条冷镦性能的影响

分析了影响冷镦开裂的主要因素 ,通过控制控轧控冷工艺中的冷却速度 ,获得了正常的显微组织 ,避免了冷镦开裂 ,提高了 35K盘条钢的冷镦性能。     

SWRCH35K冷镦钢生产工艺研究与实践

为满足市场需求,丰富产品结构,针对冷镦钢高强度、高塑性,冷镦性能好,易拉拔等性能要求,通过对盘条的化学成分、加热制度、控轧控冷等工艺进行研究,成功生产出SWRCH35K冷镦钢热轧盘条。生产实践表明,其实物力学性能、金相组织、表面质量、冷镦性能均可达到标准要求,能够满足用户的生产需求。     

10B21冷镦钢冷镦成型开裂原因分析

针对10B21冷镦钢在冷镦成型时头部发生开裂的现象,对冷镦开裂试样及未进行冷镦的拉拔钢丝分别进行化学成分、非金属夹杂物、金相组织、电子探针微区成分检测等理化性能检测.结果表明:材料近表面存在渣子是冷镦成型开裂的主要原因,根据渣子成分推测,渣子属于精炼渣卷入.     

中碳控铝钢角横裂控制

研究了板坯角部横裂纹产生机理,根据其横裂纹形成机理分别从钢水成分、全程N控制、结晶器参数、保护渣性能、二冷强度、铸机对弧精度等方面入手,对双流板坯生产工艺进行改进,达到提高铸坯表面强度、韧性的目的,从而使控铝钢连铸板坯的角横裂显著减少。     

Hot cracking susceptibility research in BTW1 austenitic high-manganese wear-resistant steel

Baosteel's first BTW1 austenitic high-manganese wear-resistant steel exhibits strong deformation-induced hardening characteristics.Compared with common low-alloy martensitic wear-resistant steels in the market,it has improved impact wear resistance,hard abrasive wear,erosion wear performance,and impact toughness.The metallurgical properties of such austenitic wear-resistant steel lead to the risk of failure because of hot cracking defects in the welded structure.In wear-resistant applications,evaluating hot cracking susceptibility is necessary to avoid the effect of welding defects.In this study,the Varestraint test is used to quantitatively analyze and evaluate the hot cracking susceptibility of BTW1 austenitic high-manganese wear-resistant steel.The test results show that by controlling the content of impurity elements and grain refinement,BTW1 austenitic high-manganese wear-resistant steel effectively reduces hot cracking tendency and has a low incidence of hot cracking under small strain conditions.The developed matching welding process can effectively avoid the influence of hot cracking susceptibility.     

焊接钢管压扁试验开裂原因的分析与对策

压扁试验是检验钢管质量的方法之一,通过分析压扁试验开裂原因来采取相应手段可解决焊接钢管压扁试验开裂问题。实验采用扫描电子显微镜(SEM)、能谱仪(EDS)和金相显微镜(OM)等设备对焊接钢管压扁试验开裂的原因主要进行两方面分析:金相分析和断口分析。金相分析可得出主要结论,断口分析验证金相分析得出最终结论。结果表明:焊接钢管压扁试验开裂的主要原因为焊接钢管内存在大量的硅酸盐类夹杂物,此类夹杂物属于高温塑性夹杂物,容易破坏基体的横向连续性,在压扁试验中可引起应力集中,促使裂纹的形成,导致钢管开裂。焊接钢管开裂的次要原因为试样存在带状组织且铁素体晶界处还分布着网状三次渗碳体,三次渗碳体塑性差,压扁时会进一步加剧裂纹的扩展。通过分析开裂的原因进而对焊接钢管生产工艺进行优化,经过钢包精炼炉(LF)精炼与控轧控冷技术可减少钢中夹杂物,进而改善焊接钢管压扁开裂问题,使钢管失效率下降,提高焊接钢管的质量。     

耐候钢05CuPCrNi焊接性研究

针对耐候钢05CuPCrNi,采用CO2气体保护焊,通过化学成分、焊接裂纹试验、对接接头力学性能试验,对其焊接性能进行检验,碳当量分析表明,该钢淬硬和冷裂倾向不大,可以不预热焊接。冷裂纹敏感系数表明,冷裂倾向不明显,接头金相及力学性能结果表明,按常规焊接工艺,所得焊接接头组织正常和机械性能优良,满足工程使用要求.经综合分析耐候钢05CuPCrNi具有良好的焊接性能.     

Evolution of MnS inclusions in Ti-bearing X80 pipeline steel

Studies show that manganese sulfide(MnS)inclusions in pipeline steel affect the lateral performance of steel in its rolling deformation,as well as the hydrogen-induced cracking and sulfide stress corrosion cracking resistance performance.To inhibit the precipitation of MnS and its effect on pipeline steel,a quenching experiment and a diffusion couple experiment,which investigated the evolution of MnS inclusions in Ti-bearing X80 pipeline steel,were conducted.The experimental results show that the transformation of the MnS inclusions during solidification is as follows:MnS→titanium sulfide(TiS)→Ti_4C_2S_2.The transition temperatures of MnS to TiS and TiS to Ti_4C_2S_2 are 1 673 and 1 273 K,respectively,and the overall size of the sulfide decreased as well.Thermodynamic calculation results confirm that the transition temperatures of MnS to TiS and TiS to Ti_4C_2S_2 are 1 623 and 1 203 K,respectively.When the sulfur content in the X80 pipeline steel is 0.001 5%,all the sulfur in the steel can be converted into Ti_4C_2S_2 with a titanium content of more than 0.02%.     

Analysis of an Orthotropic Deck Stiffened with a Cement-Based Overlay

Over the past years, with increasing traffic volumes and higher wheel loads, fatigue damage in steel parts of typical orthotropic steel bridge decks has been experienced on heavily trafficked routes. A demand exists to find a durable system to increase the fatigue safety of orthotropic steel bridge decks. A solution might be to enhance the stiffness of the traditional orthotropic bridge deck by using a cement-based overlay. In this paper, an orthotropic steel bridge deck stiffened with a cement-based overlay is analyzed. The analysis is based on nonlinear fracture mechanics, and utilizes the finite-element method. The stiffness of the steel deck reinforced with an overlay depends highly on the composite action. The composite action is closely related to cracking of the overlay and interfacial cracking between the overlay and underlying steel plate (debonding). As an example, a real size structure, the Far? bridges located in Denmark, are analyzed. The steel box girders of the Far? bridges spans 80?m, and have a depth of 3.5?m, and a width of 19.5?m. The focus of the present study is the top part of the steel box girders, which is constructed as an orthotropic deck plate. Numerous factors can influence the cracking behavior of the cement-based overlay system. Both mechanical and environmental loading have to be considered, and effects such as shrinkage, temperature gradients, and traffic loading are taken into account. The performance of four overlay materials are investigated in terms of crack widths. Furthermore, the analysis shows that debonding is initiated for a certain crack width in the overlay. The load level where cracking and debonding is initiated depends on the stress-crack opening relationship of the material.     

冷镦钢开裂原因分析及质量改进措施

介绍了冷镦钢开裂的原因及质量改进措施,旨在降低冷镦钢改判率,提高冷墩钢使用性能,减少质量异议的产生。     

TP347H管坯轧制开裂的工艺研究

对我公司TP347H管坯出现轧制开裂问题进行了研究，重点分析和讨论了TP347H钢中[O]、[S]含量和添加微量元素B对轧制开裂的影响。调整VOD的脱氧制度使钢中残Al量增加、还原炉渣的碱度提高和Si-Ca的使用改变了钢中夹杂物的性质、形态，以及吹Ar保护浇注等措施的采取，降低了钢中[O]、[S]含量及夹杂物含量，提高了钢的纯净度，加微量元素B，进一步改善钢了的热塑性，解决TP347H管坯轧制开裂问题。     

纺织钢领用GCr15冷轧钢带加工异常的原因分析

探讨了钢领用GCr15冷轧钢带的质量特性,通过对钢领冲裂部位与车削表面粗糙部位的宏观分析;裂口与粗糙表面的观察;延伸,强度和表面硬度检测,金相实验检测等,找出了钢带冲裂与车削部位表面粗糙的原因是热处理工艺不合理,组织球化不理想。通过多次改进热处理工艺,从而有效改善了带材的冷冲压性能和车削性能。     

100 t BOF-LF-VD-CC流程抗硫管线钢KS30的生产实践

抗硫管线钢主要用于加工石油、天然气的输送管道,对钢的强度、韧性、抗氢致裂纹(HIC)、抗硫应力腐蚀裂纹(SSC)和焊接性能等要求很高。结合石钢京诚生产抗硫管线钢的生产实践,对各成分的作用及影响进行了分析,并对抗硫管线钢KS30生产实践进行了介绍。在铁水P含量≤0.120%、铁水S含量≤0.050%的情况下,优选原辅料,可保证抗硫管线钢KS30成品P含量≤0.010%、S含量≤0.0015%、O含量≤0.0012%,轧材抗HIC、抗SSC性能全部合格