This study investigates the interaction between tempering processes and the formation of tempering transformation induced plasticity (T-TRIP) in 50CrMo4 steel during laser heat treatment. Various configurations, including single and double laser treatments, were examined along with different initial material states and heat treatment parameters.

This work aims to gain a deeper understanding of the mechanisms impacting distortion by working out the relationships between flow inhomogeneities in an industrial quench tank and the distortion of gear shafts. For this purpose, oil flow-modifying measures are used to induce specific shape changes on case-hardened gear shafts from commercial vehicles. The shape changes are quantified by runout and coordinate measurements.

An intensive quenching (IQ) process is an environmentally friendly method of hardening steel parts. Digitally controlled, IQ employs highly agitated and directed water flow as the quenchant. An extremely high cooling rate applied uniformly over the entire part surface area induces high surface compressive stresses which prevents part distortion and cracking while forming a very fine microstructure. The fine microstructure results in better mechanical properties compared to properties imparted by conventional oil or polymer quenching. The improved mechanical properties enable engineers to design stronger steel parts for higher power density mechanical systems often using steels containing a less amount of alloying elements or using less expensive plain carbon steels. A broad and deep body of knowledge documents IQ’s ability to tailor a steel component’s microstructure to improve steel parts mechanical properties and performance. A sampling of data will be presented including surface and core hardness, tensile, yield and impact strength, elongation and reduction in area, residual surface compressive stresses for through hardened steels and the carburized grades. IQ systems can be readily “dropped in” to existing steel processing facilities or integrated into next generation heating and cooling systems through teamed relationships with equipment makers and part manufacturers seeking a sustainable future.

The purpose of this study is to clarify the mechanical properties of the expanded austenite (S phase) formed in austenitic stainless steel (ASS). A small thin rolled plate of SUS304 with 0.5 mm thickness was used as test sample. The test sample was nitrided by active screen plasma nitriding (ASPN) at low processing temperature of 400 °C and 450 °C during 4 h processing time. S phase was formed on the surface of the test sample. The surface hardness of ASPN sample was higher than that of untreated sample. Furthermore, tensile tests and fracture surface observations revealed that the tensile strength was also improved compared to untreated samples.

One of the methods of evaluating the mechanical properties of a material in the case of its limited amount is the use of techniques that employ the miniaturized test specimens. The basic properties used mostly for residual life evaluation are tensile strength, impact notch toughness or impact notch toughness transition curve, fracture toughness, creep and high cycle fatigue. For example, by semi-destructive sampling of operating power equipment, actual material properties can be obtained which are crucial for predicting the residual life of the equipment. Furthermore, the local material properties of the weld joint in individual zones can be determined. In this paper applicability of these test methods is described, specific examples of use are given and reference is made to the existing ISO/ASTM 52909:2022 standard for the use of sub-size samples.

Hastelloy X is used in turbomachinery and petrochemical applications as it is designed for excellent oxidation and stress corrosion cracking resistance, strength, and stress rupture behavior. This alloy is now being printed via powder bed fusion processes as many industries have developed interests in the benefits additive manufacturing (AM) offers. However as-printed Hastelloy X suffers from material defect formation such as hot cracking. Hot isostatic pressing (HIP) is often applied to improve performance and reliability. Although the conventional HIP process has been shown to eliminate defects, the equipment is unable to cool at desired rates allowing the formation of excessive carbide precipitation, negatively influencing corrosion resistance and toughness. In turn the product is solution treated at a similar temperature while applying rapid gas cooling for performance requirements. With use of uniform rapid cooling available in modern HIP equipment, a high-pressure heat treatment can be applied offering the ability to perform both HIP and heat treatment in one piece of equipment. Microstructure and tensile properties are evaluated and compared to the conventional processing routes. The results demonstrate that the novel high pressure heat treatment approach offers a processing route that is equivalent to or better than conventional methods.

Press hardening steel (PHS) applications predominately use 22MnB5 AlSi coated in the automotive industry. This material has a limited supply chain. Increasing the tensile strength and bendability of the PHS material will enable light-weighting while maintaining crash protection. In this paper, a novel PHS is introduced, and properties are compared to 22MnB5. The new Coating Free PHS (CFPHS) steel, 25MnCr, has increased carbon, with chromium and silicon additions for oxidation resistance. Its ultimate tensile strength (UTS) of 1.7 GPa with bending angle above 55° at 1.4 mm thickness improves upon the 22MnB5 grade. This steel is not pre-coated, is oxidation resistant at high temperature, thus eliminating the need for AlSi or shot blasting post processing to maintain surface quality. Microstructural mechanisms used to enhance bendability and energy absorption are discussed for the novel steel. Performance evaluations such as: weldability, component level crush and intrusion testing and e-coat adhesion, are conducted on samples from industrial coils.

This paper provides an overview of salt quench hardening and how it compares with oil quenching. It explains how salt quenching promotes hardenability, ductility, and strength as well as distortion control, heat extraction, and process reduction. It discusses equipment layout configurations, NFPA guidelines and safety practices, and salt quench processes for austempering, marquenching, and neutral hardening applications.

A hypoeutectoid steel was austenitized at 840 °C for one hour and cooled at two rates. Examination by optical and scanning electron microscopy showed a change in the pearlite microstructure. Cooling in air as compared to furnace cooling reduced the pearlite interlamellar spacing and increased the hardness. The slower cooling resulted in a lower tensile strength, higher tensile elongation, and different fracture appearance.

The properties of heat treatable wrought aluminum alloys are primarily achieved through use of solution heat treatment processes defined in AMS 2770. Variation in these processes can greatly influence the final properties of the aluminum alloy material. This study specifically investigates the effects of the quenching solution used during the wrought aluminum alloy heat treatment process. The research varies the Type 1 polymer concentrations between 10 and 25 percent in the quenchant solution. The scope is limited to investigate aluminum 6061 and 7075 alloys treated to the T6 condition and uses plate stock ranging 1 to 2.5 inches in thickness. Statistical analysis is used to determine the magnitude of the effect of polymer percentage on material properties of the aluminum alloys at these conditions. This research is conducted to determine the basis for the glycol restrictions within the ranges typical to internal manufacturing processes. The conclusions of this research are based on statistical evaluation of tensile, yield, hardness, grain size and electrical conductivity results obtained as a result of the investigation.

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.

The effect of forging temperature and temperature before quenching on microstructure is studied. This is related to the mechanical properties like tensile strength, yield strength and impact toughness. It was observed that martensitic needles in direct quenched parts were slightly longer than the normal hardened and tempered parts. This was attributed to the coarser prior austenite grain size, resulting in fewer nucleation sites in case of direct quenched parts.

The 2524 aluminum alloy was cold rolled to 70% reduction and then annealed at 500? for 0.5h in an air furnace with a heating rate of 5?/min and in a salt bath with a heating rate of 75?/s, respectively. The effect of heating rate on the microstructure, tensile properties and fatigue crack growth (FCG) rate of the alloy was investigated. The microstructure and mechanical properties of the alloy were studied by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM), optical microscopy (OM), tensile and FCG rate tests. In the case of slow heating the alloy exhibited a coarse elongated grain structure (~75μm), while a fine equiaxed grain structure (~13μm) was obtained in the case of rapid heating. The sheet annealed with rapid heating has slightly higher tensile strength and yield strength, but a slightly lower elongation than the sheet annealed with slow heating. The FCG rate of the sheet annealed with slow heating is 20% lower than the sheet annealed with rapid heating.

This paper introduces two simplified equations, "Nori formulae," for calculating maximum allowable stress (MAS) in mechanical design engineering. These formulae eliminate the need for traditional safety margins or factors of safety along with factored values across applications ranging from safety pins to spacecraft components. The first formula determines the maximum allowable stress in tension, while the second addresses the maximum allowable stress in shear. The Nori formulae were developed by incorporating fundamental mechanical properties of steel: ultimate tensile strength, yield strength, elongation, and reduction of area—all commonly derived from engineering stress-strain curves in standard tensile testing. This approach effectively utilizes existing global databases of elongation and reduction of area measurements, requiring no additional data generation that would otherwise demand significant time and financial investment. This work addresses a critical gap in the field, as various international design codes and standards currently employ inconsistent design philosophies and safety margins when determining the maximum allowable stress for steel materials.

PremoMet, a cobalt-free alloy, is engineered for high strength and toughness after quenching and tempering, positioning it as a potential replacement for AISI 4140 and AISI 8630 in gear and flange production, where improved fatigue life is anticipated. Utilizing open-die forging and ring-rolling for component fabrication, optimal properties are attained through meticulous microstructure control, with heat treatment being crucial. Representative seamless rings, produced under standard industrial conditions, were segmented and subjected to varying quenching and tempering regimens to assess microstructural evolution and resulting mechanical properties. This study presents tensile, hardness, and toughness data, complemented by scanning electron microscopy (SEM) for detailed microstructural analysis.