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Pre-fatigue training technique doubles the performance of high-strength steel

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Pre-fatigue training technique doubles the performance of high-strength steel


Correlation between tensile strength and fatigue limit in steels. Credit: Kazuho Okada, National Institute for Materials Science

A NIMS research team has discovered that the fatigue limit of steel is improved by prior cyclic deformation (fatigue) training. Based on this finding, the research team developed a novel pre-fatigue training technique, which successfully doubled the fatigue limit of high-strength steel by suppressing crack initiation.

This strategy offers a versatile approach to improving the fatigue limit in general steels, providing an effective alternative to tempering that inevitably sacrifices tensile strength. The research is published in Advanced Science.

Fatigue limit—the stress level below which a material can endure for an infinite or sufficiently large number of loading cycles without failure—increases proportionally with tensile strength in steels. However, when the tensile strength exceeds 1.4 GPa (gigapascals), further increases in the tensile strength do not improve or rather decrease the fatigue limit, that is, the fatigue limit ceiling. In addition, martensitic steel, a representative , generally exhibits a low fatigue limit in the as-quenched state with the highest strength level.

As a result, before practical applications, martensitic steels are typically tempered to improve fatigue performance, sacrificing the strength level. The detailed mechanism behind the fatigue limit ceiling remains unclear, and there has been a strong demand for materials design strategies to overcome the ceiling.

Key findings

The research team successfully doubled the fatigue limit of as-quenched martensitic steel with a tensile strength of 1.6 GPa, thereby overcoming the fatigue limit ceiling. This was achieved through pre-fatigue training, which was performed under the loading condition that did not cause crack initiation.

In-depth analysis revealed that the predominant factor of fatigue crack initiation in high-strength steels is the elastic misfit—i.e., the elastic strain mismatch in the loading direction—at grain boundaries. This study is the first in the world to demonstrate that fatigue deformation, conventionally considered harmful, can suppress the above crack initiation mechanism.

'Fatigue' strengthen steels
Significant improvement of fatigue limit by suppressing crack initiation via pre-fatigue deformation in as-quenched martensitic steels. a) Relationship between tensile strength (σB) and 107 cycles fatigue limit at a stress ratio of 0 (σW(0). Credit: Advanced Science (2025). DOI: 10.1002/advs.202504165

Future outlook

Unlike tempering heat treatment, the pre-fatigue training improves the fatigue limit with minimal reduction in , making it a promising approach applicable to general high-strength steels. In addition, this study demonstrated that suppressing crack initiation, rather than the conventionally focused crack termination, is the key to improving the limit of high-strength steels.

The research team further aims to develop this “microstructural design strategy for crack-initiation-resistant materials” and apply it to fracture phenomena in a wide range of materials, including steels, which significantly contributes to making the social implementation of ultra-high-strength materials become more feasible.

This study was conducted by a research team consisting of Kazuho Okada (Senior Researcher, Steel Research Group (SRG), Research Center for Structural Materials (RCSM), NIMS), Kaneaki Tsuzaki (former Research Fellow, SRG, RCSM, NIMS), Eri Nakagawa (Ph.D. student, SRG, RCSM, NIMS), and Akinobu Shibata (Distinguished Leader, SRG, RCSM, NIMS).

More information:
Kazuho Okada et al, Fatigue Limit Doubling in High-Strength Martensitic Steel through Crack Embryo Engineering–Cyclic-Training-Driven Self-Optimization, Advanced Science (2025). DOI: 10.1002/advs.202504165

Citation:
Pre-fatigue training technique doubles the performance of high-strength steel (2025, August 26)
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Asus Made a Split Keyboard for Gamers—and Spared No Expense

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Asus Made a Split Keyboard for Gamers—and Spared No Expense


The wheel on the left side has options to adjust actuation distance, rapid-trigger sensitivity, and RGB brightness. You can also adjust volume and media playback, and turn it into a scroll wheel. The LED matrix below it is designed to display adjustments to actuation distance but feels a bit awkward: Each 0.1 mm of adjustment fills its own bar, and it only uses the bottom nine bars, so the screen will roll over four times when adjusting (the top three bars, with dots next to them, illuminate to show how many times the screen has rolled over during the adjustment). The saving grace of this is that, when adjusting the actuation distance, you can press down any switch to see a visualization of how far you’re pressing it, then tweak the actuation distance to match.

Alongside all of this, the Falcata (and, by extension, the Falchion) now has an aftermarket switch option: TTC Gold magnetic switches. While this is still only two switches, it’s an improvement over the singular switch option of most Hall effect keyboards.

Split Apart

Photograph: Henri Robbins

The internal assembly of this keyboard is straightforward yet interesting. Instead of a standard tray mount, where the PCB and plate bolt directly into the bottom half of the shell, the Falcata is more comparable to a bottom-mount. The PCB screws into the plate from underneath, and the plate is screwed onto the bottom half of the case along the edges. While the difference between the two mounting methods is minimal, it does improve typing experience by eliminating the “dead zones” caused by a post in the middle of the keyboard, along with slightly isolating typing from the case (which creates fewer vibrations when typing).

The top and bottom halves can easily be split apart by removing the screws on the plate (no breakable plastic clips here!), but on the left half, four cables connect the top and bottom halves of the keyboard, all of which need to be disconnected before fully separating the two sections. Once this is done, the internal silicone sound-dampening can easily be removed. The foam dampening, however, was adhered strongly enough that removing it left chunks of foam stuck to the PCB, making it impossible to readhere without using new adhesive. This wasn’t a huge issue, since the foam could simply be placed into the keyboard, but it is still frustrating to see when most manufacturers have figured this out.



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These Sub-$300 Hearing Aids From Lizn Have a Painful Fit

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These Sub-0 Hearing Aids From Lizn Have a Painful Fit


Don’t call them hearing aids. They’re hearpieces, intended as a blurring of the lines between hearing aid and earbuds—or “earpieces” in the parlance of Lizn, a Danish operation.

The company was founded in 2015, and it haltingly developed its launch product through the 2010s, only to scrap it in 2020 when, according to Lizn’s history page, the hearing aid/earbud combo idea didn’t work out. But the company is seemingly nothing if not persistent, and four years later, a new Lizn was born. The revamped Hearpieces finally made it to US shores in the last couple of weeks.

Half Domes

Photograph: Chris Null

Lizn Hearpieces are the company’s only product, and their inspiration from the pro audio world is instantly palpable. Out of the box, these look nothing like any other hearing aids on the market, with a bulbous design that, while self-contained within the ear, is far from unobtrusive—particularly if you opt for the graphite or ruby red color scheme. (I received the relatively innocuous sand-hued devices.)

At 4.58 grams per bud, they’re as heavy as they look; within the in-the-ear space, few other models are more weighty, including the Kingwell Melodia and Apple AirPods Pro 3. The units come with four sets of ear tips in different sizes; the default mediums worked well for me.

The bigger issue isn’t how the tip of the device fits into your ear, though; it’s how the rest of the unit does. Lizn Hearpieces need to be delicately twisted into the ear canal so that one edge of the unit fits snugly behind the tragus, filling the concha. My ears may be tighter than others, but I found this no easy feat, as the device is so large that I really had to work at it to wedge it into place. As you might have guessed, over time, this became rather painful, especially because the unit has no hardware controls. All functions are performed by various combinations of taps on the outside of either of the Hearpieces, and the more I smacked the side of my head, the more uncomfortable things got.



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CEOs are taking the lead on AI initiatives | Computer Weekly

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CEOs are taking the lead on AI initiatives | Computer Weekly


The AI radar 2026 study from Boston Consulting Group (BCG) has reported that artificial intelligence (AI) investment is set to double in 2026 compared with 2025. The study, based on a survey of 2,400 business executives, of which 640 are CEOs, found that almost every chief executive polled (94%) is committed to continuing investments even if returns take time to materialise.

In fact, almost all (90%) of the CEOs polled believe AI agents will deliver a measurable return on investment (ROI) by 2026.

The study found that over two-thirds (72%) of CEOs now act as the primary decision-maker for AI in their organisation, taking responsibility from CIOs, who were previously the main lead in AI projects.

Christoph Schweizer, CEO of BCG, said: “Corporate investment in AI is here to stay. 94% of our survey respondents say they will continue to invest in 2026, even if it takes time to see the return. They intend to spend 1.7% of revenue on AI comprehensively. That is more than twice of what it was a year ago.”

BCG’s research suggests that companies leading the way in AI deployments are investing 60% of their AI budgets on agentic AI (AI agents). “We tell CEOs that they need to make AI a key priority,” he said. “The way they own it, the way they talk about it, the way they bring their organisation along. They need to spend time on deepening their own AI literacy.”

BCG recommends that CEOs understand the tools, the technology, and keep in touch with technology suppliers and partners. “Ultimately, you need to know what you talk about so that you can bring your organisation along and steer for maximum return,” added Schweizer.

With regards to the adoption of agentic AI, BCG found that more than 30% of the CEOs investing in AI during 2026 said they would be building agents to deploy in the work environment. Vladimir Lukic, global leader of BCG’s Technology and Digital Advantage, said: “AI agents will truly be something that will unlock organisations and deliver a return on investment within 2026.”

Sylvain Duranton, head of BCG X, said the research highlights differences in CEOs’ AI confidence in different regions. BCG reported that UK businesses are less likely than global peers to make large-scale investments in AI in 2026.

The study found that only 24% of UK companies plan to invest more than $50m in AI, compared with much higher shares in countries leading the AI race, such as Greater China (68%), Japan (53%), the European Union (38%) and the Middle East (41%). BCG also reported that British CEOs are the most sceptical of AI’s potential return on investment and less involved in decision-making on AI.

Discussing the regional differences, Duranton said: “CEOs in the East, in India, in China, in Japan, the Middle East and Africa tend to be highly confident that AI is going to be a positive return on investment move. In the global West – Europe, the US and the UK – there’s a bit more caution.”

In his experience, many Asian companies have huge confidence and boldness in moving forward with AI. However, many European and US firms operate in a different way. “There’s some more skepticism in their workforce,” said Duranton. “There potentially is some more regulation that they deal with.”

Firms leading the way with AI deployments, which BCG categorise as “trailblazers”, tend to focus heavily on upskilling the workforce. Jessica Apotheker, chief marketing officer and managing director at BCG, said: “Trailblazers are putting 60% of their AI budget behind upskilling and retraining their workforce. So, they’re really wanting to go deep in the organisation, changing the way people work, putting people behind this new technology.”

BCG reported that in these organisations, 70% of the workforce has been upskilled or reskilled on AI.



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