Written by: School of Materials
Translated by: Zhao Yuhang
Edited by: William Mosteller
HIT News (School of Materials/Text) As the longest cross-sea steel structure bridge in the world, the main bridge of the Hong Kong-Zhuhai-Macao Bridge is composed of three long-span steel cable-stayed bridges, wherein, the cable capacity of the anchors directly determines the stability and service life of the cable-stayed bridge. The team of Professor Yan Mufu from the School of Materials cooperated with Jiangsu Fasten Cable Co., Ltd., to effectively improve the mechanical properties of the cable anchors—the key component of the Hong Kong-Zhuhai-Macao Bridge—and achieve the perfect match of cable anchors with the ultra-high stay cable through heat treatment and surface modification ultra-high strengthening and toughening technology, thus ensuring smooth construction of the main bridge.
The Hong Kong-Zhuhai-Macao Bridge spans the Lingding Sea and connects with Hong Kong to the East and Guangdong, Zhuhai and Macau to the West, with a total length of around 55 kilometers. The technical level and difficulty of the bridge’s steel structure and cable technology are the highest in the world, wherein, the Jianghai Zhida Ship Channel Bridge has a span of 994 meters and adopts the 1860 MPa ultra-high strength stay cable, of which the heat treatment and surface modification technology of the cable anchor is one of the key technologies for the cable-stayed bridge construction. The manufacturing level of the cable anchor is the key to ensuring the long life and high reliability of the Hong Kong-Zhuhai-Macao Bridge, related to whether or not the high strength stay cable of the anchor can hold solidly for a long time. The larger the size of the anchor, the more steel ropes can be equipped, and the higher the strength of the stay cable will be. Therefore, the technical difficulty of ensuring the mechanical properties of the anchor is significantly increased.
The anchor material of the steel structure cable-stayed bridge of the Hong Kong-Zhuhai-Macao Bridge is made of medium carbon low-alloy steel, wherein the heat treatment and surface modification are the keys to improving the mechanical properties, and the core problems encountered in the research of anchor manufacturing technology. After three years of hard work, Professor Yan Mufu's team carried out microstructural multi-scale simulations and process design based on the service performance of the anchors, forming the overall quenching structure performance control and micro-deformation control technology of large-size differential wall thickness anchors and the grain nanocrystallization technology of low-temperature thermal diffusing permeation surfaces, thus achieving the overall strengthening and toughening of the anchor and the ultra-high strengthening and toughening of the surface layer, which solves the problems of large quenching deformation of the anchor and uneven mechanical properties of the section. This achievement also breaks through the technical bottlenecks of large-size and complex structural anchorage manufacturing, thereby providing the key technical guarantee for the construction of the large-span steel structure cable-stayed bridge of the Hong Kong-Zhuhai-Macao Bridge.
Yan Mufu said: "China's level of high-end equipment manufacturing still has a lot of room for development. One of the main sources is that some key areas and core components have not been independently researched and developed. The core technologies of heat treatment and surface modification are missing, and there is a shortage of talented professionals, so we still have a lot of work to do, and a long way to go."
For more than 30 years, Professor Yan Mufu has led his team to adhere to the field of heat treatment and surface modification, and created the theory and technology of thermal diffusing permeation grain nanocrystallization, the theory and technology of plasma thermal diffusing permeation surface diamond structure, and the theory and technology of hot working zero distortion Biot number, and has applied the research results in the manufacturing of key components in the fields of aviation, aerospace, ships and warships, and rail transit. These key components have long service life and high reliability, thus achieving significant economic and social benefits. Under the leadership of Academician Zhao Zhenye, former chairman of China Heat Treatment Society, Professor Yan Mufu worked as the leader of the comprehensive team and completed the “China Heat Treatment and Surface Modification Technology Roadmap” with peer experts from relevant universities, enterprises, and research institutes across the country. As the leader, Yan Mufu led the team to create the “New Material and High-end Equipment Manufacturing Heat Treatment and Surface Modification Innovative Talent Training Model (3221 model)”, which was included in the “China Heat Treatment Industry Association Education and Training Working Committee Work Regulations”, and cultivated a batch of innovative talented individuals in the fields of heat treatment and surface modification.