Welding method of bainitic steel frog and carbon steel rail

Abstract

A method for welding a bainite steel frog and a carbon steel rail is characterized in that CrNi series austenite-ferrite dual phase steel is adopted as a connecting material; the technological process is as follows: (1) the carbon steel rail is preheated to 300-500 DEG C; (2) the carbon steel rail and the connecting material are butt-welded together; (3) the connecting material is cut and retained at the length of 20-30mm; (4) the bainite steel frog is preheated to 300-500 DEG C; (5) the retained connecting material and the bainite steel frog are flash welded; and (6) the temperature of a welding joint is preserved between 900-1,000 DEG C for 10-20 minutes, and then the welding joint is air cooled. The connecting material has the following composition (weight %): C is equal to or less than 0.2; Cr is 15-17; Ni is 7-9; Si is equal to or less than 0.3; S+P is equal to or less than 0.04; and iron is in balancing amount. The connecting material is heated to 1,050 DEG C, and then solution treatment is performed to obtain austenite-ferrite dual phase tissue, wherein the content of ferrite is 10-20%; the flash speed of flash welding is 2-3mm / s; the upset forging speed is 80-100mm / s; the upset forging pressure intensity is 40-50MPa; and the extension elongations of the material are equal during the welding process.

Description

technical field

[0001] The invention relates to a welding method for a bainitic steel frog and a carbon steel rail. Background technique

[0002] Frog is an important component of railway transportation, and it is the most seriously damaged part in the railway structure. At present, there are two kinds of fixed frogs used on my country's railways: one is a high-carbon steel composite frog, which is fastened by bolts. This kind of frog is not wear-resistant, and the bolts are easy to loosen. Defects such as cracks are formed at places, resulting in a significant shortening of life. The other is high manganese steel whole casting frog. High manganese steel frog has the characteristics of good toughness, load hardening and wear resistance. However, casting high manganese steel frog has unavoidable casting defects, such as porosity and shrinkage cavity. And the crystal grains are too coarse, etc., it is easy to cause longitudinal and horizontal cracks, vertical cracks, collapse...