辊压成型用高硬度高耐蚀性镀锌导轨钢的开发及应用

为满足导轨行业高强减薄和高耐蚀性能的需求,涟钢充分利用CSP短流程优势,采用低成本的碳锰钢并适当控制P元素的成分设计,辅以低退火温度和短退火时间的工艺设计,产品硬度达到了竞争钢厂的水平。同时对不同钝化属性的材料辊压成型后零件耐蚀性能的研究,采用三价铬钝化处理方式获得了优异耐蚀性能的镀锌导轨钢。

高耐蚀型耐候钢S450EW热轧工艺及腐蚀性能

制定了S450EW高耐蚀型耐候钢的热轧工艺,具体为:加热—粗轧—精轧—层流冷却—卷取,粗轧材料厚度控制值为40 mm,温度控制在(1050±20)℃范围内,精轧材料厚度控制值为7 mm,温度控制在(870±20)℃范围内,并对不同热轧工艺的样品进行金相试验及力学性能检测,以确定各工艺参数的设定范围。同时,完成S450EW钢的腐蚀性能验证,将试验钢的轧制成品径线切割为70 mm×50 mm×3.5 mm的板状,并在Fl-65型干湿周期浸润腐蚀试验机内进行试验。结果表明,S450EW钢的两种试验样品的平均腐蚀率分别为1.770和1.839 g·m-2·h,明显小于参比钢Q345试样的平均腐蚀率2.909 g·m-2·h。

Effect of high-speed laser cladding on microstructure and corrosion resistance of CoCrFeNiMo_(0.2) high-entropy alloy

In order to study the corrosion resistance of high-speed laser cladding(HLC) coating while improving production efficiency,a CoCrFeNiMo_(0.2)high-entropy alloy(HEA) coating was prepared by HLC.The optimized parameters of HLC are laser power of 880 W,scanning speed of 18 m/min,overlapping ratio of 60%,and powder feed speed of 3 r/min.Then,the surface roughness,microstructure,phase composition,element distribution,and electrochemical properties in 3.5 wt% NaCl solution of the coatings were analyzed,respectively.The local surface roughness of the CoCrFeNiMo_(0.2)HEA coating was found to be 15.53 μm.A distinct metallurgical bond could be observed between the coating and the substrate.Compared to the conventional laser cladding(CLC),the results of electrochemical tests showed that CoCrFeNiMo_(0.2)HEA coating exhibited a significant passivation.The corrosion current density of 5.4411 × 10^(-6)A·cm^(-2) and the corrosion potential of-0.7445 V for the HLC coating were calculated by the Tafel extrapolation method.The CLC coating’s corrosion current density and corrosion potential are 2.7083×10^(-5)A·cm^(-2) and-0.9685 V,respectively.The HLC coating shows a superior corrosion resistance,crucially due to the uniform and fine grains.Under various complex and harsh working conditions,this method can be widely used in the field of repairing and remanufacturing of corro sion-proof workpiece s.

Comparative study of microstructure and corrosion resistance of electroless Ni-W-P coatings treated by laser and furnace-annealing

A comparative study of amorphous electroless Ni-W-P coatings on mild steel substrate treated by a high power diode laser and furnace annealing was presented.Effects of different laser operating parameters and furnace-annealing conditions on microstructures,in terms of crystallisation,pores formation and grain growth,were investigated using SEM/EDX and XRD. Corrosion behaviours of these coatings before and after various treatments were evaluated with anodic polarisation in 0.5 mol/L H2SO4 solution.The results show that the furnace-annealing produces either a mixture of nanocrystallined Ni and amorphous phases or precipitated Ni3P phase distributed in nanocrystallined Ni-based matrix,depending on annealing temperatures,whilst the laser treatment under the operating conditions only produces nanocrystallined Ni-based matrix with Ni3P precipitates.Corrosion performance of the coatings treated by both the laser and the furnace-annealing is dependent on the annealing temperature and laser operating conditions.Corrosion mechanisms of various treated-coatings were discussed in the consideration of phase constitutes and proportion,grain sizes of both Ni and Ni3P phases,pores formation and residual stresses.

我国汽车用钢开发应用现状及发展趋势

我国汽车用钢的开发和应用经历了从无到有,再到逐渐追赶世界先进钢企的过程。进入21世纪,随着汽车用钢生产技术的进步和主机厂对整车轻量化要求的提高,我国开发出了强度更高、塑性更好的汽车用钢系列产品,为主机厂提供了满足不同设计需求的关键汽车用钢材料。结合我国及世界汽车用钢市场的主要需求,概述了我国主要汽车用钢生产厂家在产品开发和应用推广上的进展,介绍了生产高品质产品所需的关键装备,同时介绍了先进汽车用钢应用所需要解决的关键问题。此外,随着我国双碳战略的提出,我国汽车用钢的发展进入了一个新的阶段,低碳、近零碳材料的开发成为了热点,对未来我国汽车用钢开发和应用进行了展望。