生产锚链钢SBC690的工艺实践

北满特钢通过90t电弧炉-LF（VD）精炼-250mm×280mm方连铸一连轧工艺生产锚链钢SBC690（0．31％C、0．25％Si、1．70％Mn、0．030％Al）。通过VD处理和全过程无氧化保护浇铸,使N的质量分数≤89×10^-6,钢中夹杂物为0-2级,晶粒度、性能均满足标准要求。     

一种新型980MPa高强钢在不同温度下的拉伸断裂试验

本文通过在不同温度下,对一种轧制而成的贝氏体高强钢在三个相互垂直的方向进行了拉伸实验,结合宏观力学性能参数及微观断口形貌的观察,分析了这种高强钢在不同温度下的拉伸断裂行为。结果表明:此种钢在三个方向上的宏观力学性能参数基本相同(在室温下屈服强度为950MPa,抗拉强度为1000MPa;-196℃下,屈服强度达到1260MPa,抗拉强度高达1400MPa)。但沿不同方向的拉伸断口差异却很大。沿轧制方向和宽度方向的试样,不同温度下断口形貌相似,在温度较低的试样中都出现了纵向裂纹,在-196℃均出现"Z"型断裂路径;但沿板厚方向的试样,在不同温度下其断口形态都为典型的拉伸断口。     

超超临界火电机组用锅炉钢技术国产化问题

综述了国内外超超临界火电机组技术的发展及其对中国实现节能减排战略目标和保障国家能源安全的重大意义,阐明了先进锅炉钢技术是支撑超超临界火电机组技术发展的关键所在和物质基础。总结了近20年来中国锅炉钢技术研究的进展、国家研究计划以及与国外先进水平的差距。重点介绍和分析了超超临界火电机组建设用关键锅炉钢(T/P92、S30432、和S31042)国产化过程中面临的主要技术问题及解决措施,同时探讨和展望了中国先进锅炉钢未来的发展方向。     

Local approach to fracture-based prediction of reactor pressure vessel lifetime

New version of the local approach to fracture is presented. Within the framework of this approach a new methodology is developed, which provides prediction of radiation life time of a reactor pressure vessel not by ultimate shift of the Charpy critical temperature, ΔT_K, or by reference temperature, ΔT₀, but by the condition of brittle fracture initiation of irradiated metal ahead of a crack tip in reactor pressure vessels. __________ Translated from Problemy Prochnosti, No. 1, pp. 53–60, January–February, 2009.     

超细晶粒高碳钢的研究现状及展望

晶粒超细化能同时提高材料的强度和韧性,是新一代钢铁材料研究与开发所追求的重要目标,而超细晶粒高碳钢则是新一代钢铁材料中具有重要发展前景的高性能结构材料.综述了超细晶粒高碳钢细化技术的主要研究成果,简述了高碳钢组织超细化的具体工艺、适用条件及应用情况等,并从工业应用角度分析了现有超细晶粒高碳钢制备技术的主要问题和研究方向.     

热轧TRIP钢的加工工艺与残余奥氏体形成的关系

低合金TRIP钢的显微组织中残余奥氏体使其具有优良的强度和延性组合。分别介绍了热轧TRIP钢在奥氏体再结晶区、未再结晶区以及临界区变形对残余奥氏体形成的影响。分析了输送台上的冷却和卷取温度对残余奥氏体形成的影响。对低合金TRIP钢残余奥氏体的形成等物理冶金学的研究可以促进该类合金的开发和推广应用。     

汽车变速操纵杆焊接接头冷裂纹产生原因分析

汽车变速操纵杆ZG310-570钢与45钢焊接接头焊后发现产生冷裂纹。采用化学成分分析和金相检验的方法对冷裂纹的产生原因进行了分析。结果表明：焊接接头出现淬硬组织以及粗大的魏氏组织是导致冷裂纹产生的主要原因;另外焊条含有的水分、焊件表面的油污和铁锈以及接头的拘束应力也会影响到冷裂纹的产生。并提出相应的预防措施。     

Yb:YAG laser welding of TRIP780 steel with dual phase and mild steels for use in tailor welded blanks

Advanced high strength steels (AHSS) are essential to meet the demands of safety and fuel efficiency in vehicles. In this paper, we present the results of laser welding of two AHSS steels, TRIP780 and DP980. A 2 kW Trumpf TRUDISK 6002^® Yb:YAG laser beam was utilized to join 1 mm thick TRIP780 with 1.5 mm thick DP980 and 1 mm thick mild steel. Optical metallography was used to characterize the weld profile and microstructures. Microhardness, tensile and fatigue tests were performed to evaluate the mechanical properties. Results indicate that the laser welds exhibit excellent strength and hardness with minimal defects which are attributed to the high beam quality, disk type of laser. In addition, there is a distinct effect of pre-straining of TRIP780 steels on the energy absorption.     

Effect of shear cutting on ductility of a dual phase steel

Both an experimental investigation with an especially designed setup and a mechanical FE analysis of the cutting process showed that for the laboratory dual phase steel investigated, cutting involves positive stress triaxiality and ductile fracture mainly due to void nucleation and coalescence at ferrite-martensite interfaces. Tensile tests on as-cut strip specimens showed a large reduction in ductility due to the presence of damage on the edges of the strips. Tensile tests on strip specimens containing short precracks and mechanical analysis showed that the cutting affected area behaves as a precrack during subsequent mechanical testing.     

Sintering of ferrous metallic compacts: Chemical reactions that involve interstitial elements

For sintering of ferrous metallic compacts, the chemical reactions with the atmosphere are of special interest. This is due to the very large specific surface of the compacts that makes them highly reactive with the atmosphere, much more than cast and wrought metals. Within this paper, the interactions of interstitial elements with the metallic matrix and the surrounding atmosphere are described. The main reaction partners are interstitial elements that may emerge from the starting powders or from the surrounding atmosphere. The oxidation/reduction and decarburization phenomena have been studied by thermoanalytical techniques both for mixed and prealloyed systems. The reaction mechanisms are discussed as well as their impacts on the sintering processes and the resulting properties. Oxygen transfer reactions (“Internal gettering”) and formation of methane are observed for systems with widely varying oxygen affinity of the components. The results presented show that controlling the interactions of the interstitial elements with the metallic components is crucial for successful sintering of advanced PM alloy steels.