Abstract

The central groove is a key component of armored face conveyor. Failure of welded joints in the central groove often occurs in engineering. In this article, the welding procedure parameters were analyzed to the improve strength and toughness of the dissimilar steel weld joint in the central groove. First, four types of super-high wear-resistant steel and two types of high-strength welding wire were chosen as the welding materials. Carbon equivalent method, cold crack sensitivity index method, and maximum hardness of heat-affected zone test were applied to analyze their welding properties. Second, to improve their weldability, the proper preheating temperature was determined using Y-groove cracking test and mechanical property tests. Finally, a semi-automatic CO2welding method was adopted, and a second mechanical property test was conducted to determine the proper welding wire. Results show that the chosen steels have poor weldability and cold cracking sensitivity. Preheating must be used to prevent cold cracking. When the preheating temperature is higher than 80°C, the cold crack rate can be controlled to under 20%, which can satisfy application requirements. Welding wire YMGR76 is appropriate. Using YMGR76, the preheating temperature drops to 120°C, and the strength and toughness of the weld joint are improved to 813 MPa and 112 KV2/J, respectively. This study provides a welding procedure to improve the reliability of the central groove.

Highlights

  • Coal is one of the most important energy sources, both in China and in the world

  • The conclusions in this study provide a basis for the improvement of the welding procedure of the central groove to improve the reliability of the conveyor

  • Weldability and cold cracking of the welding wire and the base metal obtain the mechanical properties of the welded joint (Figures 11 and 12)

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Summary

Introduction

Coal is one of the most important energy sources, both in China and in the world. The central groove located in the middle of the armored face conveyor is an important stressed component. The reliability and wear resistance of the central groove affect the conveyor operation and the normal safety of the coal mine during production. The central groove is a typical engineering application of structures with welded joints of dissimilar steels. It is an assembly composed of the edge, the middle plate, and the seal baseboard. The middle plate and seal baseboard are made of the same material, such as super-high wear-resistant steels

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