Steel for Nb-Ti composite microalloyed high-temperature vacuum carburizing heavy-duty gear

Abstract

The invention relates to steel for an Nb-Ti composite microalloyed high-temperature vacuum carburizing heavy-duty gear. The steel is prepared from the following components in percentage by mass: 0.15-0.23 percent of C, 0.10-0.40 percent of Si, 0.45-0.90 percent of Mn, 1.50-1.80 percent of Cr, 1.40-1.70 percent of Ni, 0.15-0.55 percent of Mo, 0.02-0.08 percent of Nb, 0.015-0.08 percent of Ti, smaller than or equal to 0.020 percent of P, smaller than or equal to 0.020 percent of S and the balance of Fe and inevitable impurities. For the steel provided by the invention, by adopting a composite microalloying manner, adding Nb and Ti microalloy elements and controlling the contents of the Nb and Ti microalloy elements, a precipitated phase is utilized to pin a crystal boundary to inhibit coarsening and growth of austenite grains in the high-temperature vacuum carburizing process, increase of the steel carburizing temperature of the heavy-duty gear is realized, the gear carburizing heat treatment process time is effectively shortened, the energy consumption is greatly lowered, and the production cost of the gear is saved.

Description

technical field [0001] The invention belongs to the technical field of alloy carburizing steel, in particular to a kind of Nb, Ti composite microalloying steel for high-temperature vacuum carburizing heavy-duty gears. Background technique [0002] Gear products are the key basic parts of the construction machinery industry. With the development of industries such as automobiles, high-speed rail and wind power, high-speed and heavy-duty have become the key development directions. Drawing on the experience of industrially developed countries, the development trend of heavy-duty gear steel is to replace high Cr and Ni alloy steel with less Cr, Ni and Mo alloy steel. Since heavy-duty gears have higher requirements on mechanical performance indicators such as strength, wear resistance, fatigue strength, and impact toughness than ordinary gears, deep carburizing treatment is often required. However, the traditional gas carburizing temperature in my country is generally 930°C, and...

AI Technical Summary

Problems solved by technology

[0007] The purpose of the present invention is to provide a kind of Nb, Ti composite micro-alloyed high temperature vacuum carburized heavy-duty gear steel to solve the problems of low carburizing temperature and long process cycle in the heat treatment process of traditional heavy-duty gear steel

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