THIS COMPILATION OF Selected Technical Papers, STP1623,Bearing Steel Technologies: 12th Volume, Progress in Bearing Steel Metallurgical Testing and Quality Assurance, contains peer-reviewed papers that were presented at a symposium held May 15-17, 2019, in Denver, CO, USA. The symposium was jointly sponsored by ASTM International Committee A01 on Steel, Stainless Steel and Related Alloys, and Subcommittee A01.28 on Bearing and Power Transmission Steels. Symposium Chair and STP Editor: John M. Beswick Montfoort, The Netherlands TABLE OF CONTENTS Overview Review on Crack Initiation and Premature Failures in Bearing Applications Influence of Steel Cleanliness on RCF and WEC Formation Rolling Contact Fatigue Transformations in Aero Steels: The Effect of Temperature on Microstructural Decay Quantitative Ultrasonic Characterization of Subsurface Inclusions in Tapered Roller Bearings Design and Validation of a Modular Rolling Contact Fatigue/Rolling-Sliding Contact Fatigue Testing Machine Investigation of Fatigue Behavior around Nonmetallic Inclusion Using a Newly Developed Rolling Contact Fatigue Test Method Lubricant-Induced White Etching Cracks: Mechanism and Effects of Surface Finishing Surface Damage in Rolling Bearings and the Impact on Rolling Contact Fatigue Effect of MnS on the Micropitting Behavior of Through Hardened Bearing Steel during Rolling Contact Fatigue Influence of Material, Heat Treatment, and Microstructure in Resisting White Etching Crack Damage Selective Laser Melting (SLM) of M50NiL---Enabling Increased Degrees of Freedom in New Design Concepts Manufacturing of Large-Diameter Rolling Element Bearings by Steel-Steel Multimaterial Systems Ultrasonic Evaluation of Tailored Forming Components Improved Processing Techniques for Inclusion-Free Steel for Bearing and Mechanical Component Applications Performance and Reliability of Powder Metallurgy Steels for Aerospace Bearings The Use of SEM-EDS and PDA-OES Techniques to Help the Development of the Production of Bearing Steel Advances in Billet Cast Carbon Steel Quality for High-Performance Rolling Bearings Improvements in GCr15 (52100) High Carbon Bearing Steel Steelmaking and Their Effect on Inclusions, Segregation, and Fatigue Properties Temperature-Resistant, Corrosion-Tolerant Carburizing Bearing Steel for Aero-Engine Applications High Performance Ferrium Steels for Aerospace Gearing and Bearing Applications Hybrid Steel and Its Potential for Bearing Applications Effect of Carbide Segregation on Mode I Fatigue Resistance Properties of the Bearing Tool Steel Roll Blade Die Relevance of Fracture Mechanics in Rolling Bearing: Functional Property Determination and Steel Quality Assurance VIM-VAR Steelmaking for Bearing Steel Grades Melt Methods and Their Effects on Cleanliness for Bearing Performance Spall Propagation Characteristics of Life-Tested VIM-VAR M50 and Pyrowear 675 Bearing Steels Spall Propagation Characteristics of As-Manufactured Aerospace Bearing Steels Testing to Reveal Tribology Mechanisms for Advancing Bearing Steels Adhesive Wear Performance of Pyrowear 675 in All-Metal and Hybrid Configuration Accelerated Life Testing of Pyrowear 675 Material at 218C (425F) Using a Ball-on-Rod Rolling Contact Fatigue Tester