Heat-resistant 10.9-grade fastener steel for rail transit and heat treatment process thereof

Abstract

The invention discloses heat-resistant 10.9-grade fastener steel for rail transit and a heat treatment process thereof. The 10.9-grade fastener steel comprises the following components in percentage by weight: 0.10%-0.20% of C, 0.10%-0.40% of Si, 0.30%-0.60% of Mn, 1.30%-1.60% of Cr, 0.20%-0.40% of V, 4.00%-4.50% of Ni, 0.80%-1.20% of W, 0.015%-0.040% of Alt, 0.40%-0.80% of Co, less than or equalto 0.015% of P, less than or equal to 0.0015% of S, less than or equal to 0.015% of O, less than or equal to 0.006% of N, and the balance Fe and other unavoidable impurities. The heat-treated structure of the fastener steel is tempered sorbite, the normal-temperature mechanical property and the high-temperature mechanical property of 450 DEG C reach 10.9 levels, and the notch sensitivity NSR valueis greater than or equal to 1.65, the minus 80 DEG C low-temperature impact toughness is greater than or equal to 75 J, and heat-resistant 10.9-grade fastener steel is suitable for manufacturing heat-resistant 10.9-grade high-strength bolts for rail transit in cold areas.

Description

technical field [0001] The invention belongs to the technical field of steel for fasteners, and in particular relates to a heat-resistant grade 10.9 steel for fasteners used in rail transit and a heat treatment process thereof. Background technique [0002] Fasteners are the basic industry of my country's equipment manufacturing industry. Domestic railway construction has maintained rapid development. Not only the new railways and the transformation of existing lines have provided new market demand for high-speed EMUs, high-power locomotives, and heavy-duty trucks, but also in-service The upgrading of equipment also provides market space for fasteners. In recent years, the development of high-strength fastener steels with special properties is a hot topic. [0003] Chinese patent CN 106086652 A discloses a high-strength heat-resistant cold-heading steel wire rod and its production method. The high-strength bolts made of the obtained wire rod serve at high temperatures, can m...

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Problems solved by technology

[0003] Chinese patent CN 106086652 A discloses a high-strength heat-resistant cold-heading steel wire rod and its production method. The high-strength bolts made of the obtained wire rod serve at high temperatures, can maintain good strength and toughness indicators, and have good durability. High temperature stability, strength and thermal strength, but the steel in this method does not have excellent low temperature toughness, so it is not suitable for fasteners used in rail transit across cold regions

Chinese patent CN 106929623 B discloses a preparation method of a 10.9 grade high-strength bolt steel hot-rolled round wire rod. The high-strength fastener bolt steel hot-rolled round wire rod produced by this patent has high cleanliness and hardenability Good, suitable strength and hardness, excellent plasticity and toughness and cold heading and upsetting deformation ability, the disadvantage is that the steel does not have significant heat resistance, and is not suitable for fasteners that need to experience high temperature conditions

[0004] To sum up, although there is a certain technical accumulation in heat-resistant fasteners and high-strength fasteners in China, there are few studies on steel for heat-resistant fasteners in the rail transit industry.

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