Microalloyed steel

About: Microalloyed steel is a research topic. Over the lifetime, 2183 publications have been published within this topic receiving 33586 citations.

Marine environment corrosion-resistant steel rail

Abstract: The invention relates to a steel rail material, and in particular relates to a marine environment corrosion-resistant steel rail The technical problem to be solved by the invention is to provide a marine environment corrosion-resistant steel rail The marine environment corrosion-resistant steel rail is prepared by adopting a heat treatment method comprising the following steps: performing accelerated cooling on the steel rail which is subjected to hot rolling and is positioned in an austenitic phase area at a cooling speed of 2-5 DEG C/s; stopping accelerated cooling until the temperature of a rail head tread is reduced to be less than 480 DEG C, and air-cooling to room temperature to obtain a steel rail finished product, wherein a microscopic structure of the steel rail finished product is a pearlite consisting of lamellar ferrites and cementite alternately distributed among the lamellar ferrites; the separation distance among pearlite sheets is not more than 120nm; the tensile strength of the steel rail finished product is more than or equal to 1200MPa, and the elongation percentage of the steel rail finished product is more than or equal to 10% The steel rail disclosed by the invention is capable of resisting marine environment corrosion, has a corrosion rate of less than 1/2 of that of carbon and ordinary microalloyed steel rails under equal conditions in a marine environment, and is suitable for application in heavy haul railways with high transportation capacity and high axle load in coastal regions

Hot rolling flat steel for high toughness X80 elbow and production method thereof

Abstract: The invention relates to hot rolling flat steel for a high toughness X80 elbow and a production method thereof and belongs to the technical field of low carbon microalloyed steel. The hot rolling flat steel for the high toughness X80 elbow comprises the following components in percentage by weight: 0.060-0.085% of C, 0.10-0.35% of Si, 1.40-1.80% of Mn, less than or equal to 0.015% of P, less than or equal to 0.003% of S, 0.04-0.07% of Nb, less than or equal to 0.06% of V, 0.010-0.020% of Ti, 0.15-0.50% of Ni, less than or equal to 0.20% of Cr, less than or equal to 0.50% of Mo, 0.010-0.040% of Al, less than or equal to 0.50% of Ceq, less than or equal to 0.23% of Pcm and the balance of Fe and inevitable impurities. A production process comprises the following steps: preparing molten iron in a blast furnace, pre-desulphurizing the molten iron, smelting in a converter, refining under LF and RH conditions, continuously casting slab, heating slab, rolling by adopting a 4300 rolling mill, rapidly cooling by virtue of ACC (activated calcium carbonate), cooling in heap, sampling and testing as well as warehousing and despatching. The hot rolling flat steel for the high toughness X80 elbow has the advantages that mechanical performance indexes of a steel plate are stable, plasticity and toughness are high, and excellent toughness is still maintained after high temperature baking, moulding and heat treatment are carried out.

Sulphide stress corrosion cracking of multiple welding repairs of girth welds in line pipe

Abstract: The susceptibility to sulphide stress corrosion cracking (SSCC) of four conditions of shielded metal arc welding repairs and one as welded specimen of the girth weld in seamless API X-52 microalloyed steel pipe were evaluated using slow strain rate tests. The slow strain rate tests were performed in air and in a NACE solution saturated with H2S both at room temperature to a constant elongation rate of 25·4 × 10–6 mm s–1. The SSCC susceptibility was evaluated in function of the reduction in area ratio and elongation ratio and also was manifested as a decrease in the mechanical properties. According to this consideration it is clear that all the weldments exhibit a great susceptibility to SSCC. After failure, the fracture surfaces were observed in the scanning electron microscope. The metallographic observations of the fractured specimens showed that the most susceptible area to SSCC was the intercritical heat affected zone.

FACTORS CONTROLLING HAZ AND WELD METAL TOUGHNESS IN C-Mn STEELS

Abstract: Recent information on metallurgical, welding procedural and other factors which control the toughness of heat affected zones (HAZs) and weld metals is reviewed. The paper deals with C-Mn and C-Mn microalloyed steel weldments in the as-welded condition.