• Mildebrath, Maximilian
• Maier, Hans Jürgen
• Pape, Florian
• Hassel, Thomas
• Poll, Gerhard
• Coors, Timm

Abstract

<p>Ensuring the reliability of wind turbine (WT) generators and reducing maintenance intervals are major levers for reducing the levelized cost of energy and thus increasing competitiveness of WTs. With increasing development in the energy sector, the dimensions and load of individual components such as slewing bearings also rise nonlinearly. To manufacture such bearings with a diameter of a few meters, low-alloy heat-treatable steels are commonly used. In order to optimize large-diameter rolling element bearings, a novel process chain for the resource-efficient production of these machine elements using steel-steel multimaterial systems has been developed. A high-quality bearing steel with a high resistance to wear and fatigue, such as AISI 52100 or better, is applied by plasma powder deposition welding on low-cost steel blanks. The base material fulfils basic requirements regarding structural load-bearing capacity, thus serving as a support structure. High-strength steel serves as a raceway for a rolling element bearing and extends over the fatigue life-determining material volume under cyclic rolling contact fatigue. This hybrid workpiece is then formed by ring rolling, which guarantees material- and process-related advantages. For bearing dimensions of several meters in diameter, this approach can be more economical and can result in better material properties than producing a bearing consistently from high-quality and high-purity bearing steel. First results of this approach are presented, in which the process described here was performed on cylindrical roller thrust bearings and a cylindrical roller bearing inner ring as analogy models on a laboratory scale. Here, an AISI 52100 cladding was welded onto a lower-strength base material (AISI 1022M). Microsections after welding, forming, and heat treatment are presented, showing a recrystallization and microstructure transformation. Bearing fatigue tests were carried out, which showed good agreement to classical rolling contact fatigue theory. These findings will later be scaled to larger geometric dimensions.</p>

Topics

• Deposition
• impedance spectroscopy
• microstructure
• theory
• strength
• steel
• fatigue
• forming
• recrystallization