In this study, a single-sided carburized Almen strip made of Pyrowear 675 is used to investigate the effect of phase transformations on quench hardening distortion. Computer modeling is used to analyze the collected experimental data and demonstrate the underlying principles of distortions and residual stress.

Recent destructive analysis of six ASTM A350 LF2 flanges has revealed vastly different low temperature (-50°F) Charpy impact toughness from 4 J (3 ft-lbs) to greater than 298 J (220 ft-lbs). These relatively low strength flanges, minimum 248 MPa (36 ksi) yield and 483-655 MPa (70-95 ksi) tensile strength, had nominally the same yield and UTS despite the difference in toughness. Detailed chemical and microstructural analysis was undertaken to elucidate the cause of the toughness range. The majority of the flanges had aluminum additions and a fine grain size with the toughness differences mostly explained by the cooling rate after normalizing with the still air cool showing the lowest toughness and the fastest air cooled sample the highest. For flanges of this strength level a quench and temper operation is not required to obtain good low temperature toughness but forced air cooling after normalizing is a minimum cooling rate to ensure good toughness and overall strength.

An attempt was made to characterize microstructure, mechanical properties and cleanliness of continuous cast as rolled billets versus microstructure, mechanical properties and cleanliness of the forging in normalized condition, upset forged from AISI 41B30 modified chemistry billets. Two forgings were compared, one in as forged condition and one in normalized or heat treated condition. Upsets were produced by upsetting only one end of the billet by hydraulic press. Samples from cold portion of the forgings, near the flange location and from flanges were taken and examined. Results of microstructure, mechanical properties and hardness are presented. Normalizing cycle did not improve mechanical and impact properties. Low impact and ductile properties are results of Widmanstätten structure and continue to be present in the final product. Low impact and ductile properties of this structure might not be the best solution for dynamically loaded parts.

Case carburizing grade steel forgings are often normalized or iso-annealed to improve machinability. The aim here is to get a uniform ferrite-pearlite microstructure and controlled, uniform hardness. Since during forging material is above austenitizing temperature, controlled slow cooling after trimming can give similar results. In this work, the effect of forging temperature and cooling rate at different stages on microstructure is studied. Further the effect of this process on machinability and distortion behavior of gears during case carburizing is studied. It was observed that the controlled cooled gear blanks had coarse grain size resulting in superior machinability, and no change was observed in the distortion behavior of the gears during case carburizing.

Direct fired and electrically heated box furnaces are used to normalize and anneal long products. The two different processing temperatures for annealing and normalizing stainless, or alloy, steel introduce the need to optimize furnace performance at two distinct temperature ranges, both on the high end and low end. Furnace designs to achieve a benchmark temperature spread are reported. Considerations such as combustion control, PID tuning and controls will be discussed.

Forgings traditionally undergo normalizing or iso-annealing processes to achieve consistent hardness within controlled bands and to improve machinability. The need for these heat treatments stems primarily from the uncontrolled cooling of forgings after trimming operations. This paper demonstrates that similar results can be achieved through controlled cooling rates after trimming, with only minor differences in specific properties. The microstructure obtained through controlled cooling is predominantly coarse-grained, consisting of pearlite and ferrite matrices, contributing to improved machinability. Notably, the controlled cooling process offers potential energy savings of approximately 20 kg of oil per metric ton of net forging weight, with corresponding reductions in CO₂ emissions of up to 250 kg per metric ton. Implementation requires a specially designed cooling tunnel to regulate cooling rates precisely. This paper details the mechanical properties achieved for a carburizing grade steel, discusses necessary refinements to steel specifications, and outlines the process controls required to replace conventional normalizing/iso-annealing with controlled cooling effectively. Additionally, the paper presents the established cycles and cooling rates that produce optimal results in production environments.

Requirements for greater product flexibility in the heat treating industry, driven by lean strategies, have resulted in growing global capacity for induction heating operations as well as the re-examination of processes to save production time and line space. However, there are important considerations to keep in mind when developing and modifying heat treat recipes whether for full-body, full-length heat treating, or seam normalizing applications. These include consideration of specialty alloy requirements and the presence of micro-alloying elements, the prior microstructure and presence of heavily banded structures, heating and cooling rates, and phase transformation kinetics especially with overheating and undercooling situations. This paper focuses on the intersection of theory and practical application for induction heating operations. Particular attention is paid to induction heating principles and fundamentals as well as new and proven methods for recipe generation.

Due to their diverse microstructures, micro-alloyed steels are increasingly being adopted across various industries. While extensive literature exists on the processing routes of these steels, experimental data on their suitability for fracture mechanics-based design and manufacturing approaches is relatively scarce, particularly in two areas: (1) the alteration of fundamental fracture mechanics properties of micro-alloyed steels in the presence of structural restraints such as pre-stress and pre-strain, and (2) a comparative study of the effect of heat treatment practices on the fracture mechanics properties of micro-alloyed steels relative to their as-rolled conditions. This study addresses these gaps by experimentally determining the quasi-static initiation fracture toughness (J1c) of low carbon (0.19%) micro-alloyed steel in its as-rolled condition, following ASTM E-1820 standards, without any heat treatment. Additionally, the study examines the effects of normalizing, shot-peening, and cyaniding followed by shot-peening on the fracture toughness parameter. The results indicate that normalizing, shot-peening, and cyaniding, followed by shot-peening, positively influence the initiation fracture toughness of this micro-alloyed steel.