The relationship between 100Cr6 steelmaking, inclusion microstructure and rolling contact fatigue performance

A processing-microstructure-performance approach is followed to study three bearing steel samples manufactured from the most frequently used continuous casting routes. The inclusion microstructures of the samples were altered by varying the metallurgy and hot working conditions. Inclusion size distribution information is obtained, showing the steel-making route that results in the highest cleanliness. 3D analysis of inclusion morphologies using electrolytic extraction indicates the irregularities on the surface to be favourable sites for crack nucleation under RCF. Flat-washer and ball-on-rod tests were conducted to study the rolling contact fatigue life of the steels, with the results from the flat-washer testing method being more representative for bearing life. This research suggests that early fatigue of bearings is governed by silicate fragmentation and late fatigue by TiN inclusions

Evidence of Noncollinear Spin Texture in Magnetic Moir\'e Superlattices

Moir\'e magnetism, parallel with moir\'e electronics that has led to novel correlated and topological electronic states, emerges as a new venue to design and control exotic magnetic phases in twisted magnetic two-dimensional(2D) crystals. Here, we report direct evidence of noncollinear spin texture in 2D twisted double bilayer (tDB) magnet chromium triiodide (CrI$_3$). Using magneto-optical spectroscopy in tDB CrI$_3$, we revealed the presence of a net magnetization, unexpected from the composing antiferromagnetic bilayers with compensated magnetizations, and the emergence of noncollinear spins, originated from the moir\'e exchange coupling-induced spin frustrations. Exploring the twist angle dependence, we demonstrated that both features are present in tDB CrI$_3$ with twist angles from 0.5$^o$ to 5$^o$, but are most prominent in the 1.1$^o$ tDB CrI$_3$. Focusing on the temperature dependence of the 1.1$^o$ tDB CrI$_3$, we resolved the dramatic suppression in the net magnetization onset temperature and the significant softening of noncollinear spins, as a result of the moir\'e induced frustration. Our results demonstrate the power of moir\'e superlattices in introducing novel magnetic phenomena that are absent in natural 2D magnets

New tranylcypromine derivatives containing sulfonamide motif as potent LSD1 inhibitors to target acute myeloid leukemia: design, synthesis and biological evaluation

Lysine-specific demethylase 1 (LSD1) is frequently elevated in acute myeloid leukemia (AML) and often leads to tumorigenesis. In recent years, numerous LSD1 inhibitors based on tranylcypromine (TCP) scaffolding have reached clinical trials. Most TCP derivatives were modified at the amino site of cyclopropane motif. Herein, we for the first time introduced a sulfonamide group in TCP benzene ring of series a compounds and performed a systematical study on structure and activity relationships by varying sulfonamide groups. The introduction of sulfonamide significantly increased the targeting capacity of TCP against LSD1. Moreover, we discovered that the Boc attached LSD1 inhibitors (labelled as series b compounds) substantially improved their anti-proliferation capacity towards AML cells. The intracellular thermal shift and LC-MS/MS results implied that Boc enhanced the drug lipophilicity and might be removed under the cancerous acidic environment to release the real pharmacophore, evidenced by the fact that a structurally similar but acidic inert pivaloyl to replace Boc dramatically dropped the cellular anti-proliferation effect. Finally, a benzyl group installed at the amino site to appropriately increase lipophilicity led to trans-4-(2-(benzylamino)-cyclopropyl)-N,N-diethylbenzenesulfonamide a10 that showed better anti-proliferation activity in AML cells and enzymatic inhibition against LSD1. Taken together, our work offers a novel TCP-based structure and provides a prodrug strategy for the discovery of potent LSD1 inhibitors by having appropriate lipophilicity

Microstructures and Mechanical Properties of 7Mn Steel Manufactured by Different Rolling Processes

We investigated both the microstructures and tensile properties of 7Mn steel, which was either hot-rolled, warm-rolled or cold-rolled before intercritical annealing at 700 °C for 5 h. It can be concluded that the warm-rolled and annealed microstructures are a kind of mixture of hot rolled and cold rolled ones. They are composed of ferrite and retained austenite, the latter having a wide size distribution and two types of morphologies: equiaxed and lamellar. These retained austenite grains are expected to transform to martensite in a more sustainable way—the warm-rolled and annealed steel exhibits the best combination of ultimate tensile strength and total elongation among the three studied steels and a shorter yield point elongation than the cold-rolled one

Erosion mechanism of high strength and toughness medium manganese steel under simulated scour of Yellow River water and sediment

The MCF-30 testing machine was used to simulate scour of Yellow River Water and Sediment, and the eroding mechanism of high strength and tough medium Mn steel and the relationship of the anti-abrasion performance and mechanical properties with several materials used for pump impeller were studied. The results show that the microcracking is often initiated at the interfaces of austenite and martensite and gradually develops into cavitation pits, the latter finally grows to much larger scale pits due to aggravated cavitation and damage caused by water and sediment impact. At the same time, the increase of phase interface leads to the decrease of the anti-abrasion performance. As the temperature increases, the austenite volume fraction of medium Mn steel increases from 16.4% to 22.9%, and the mass loss rate increases from 2.6 g·m-2·h-1 to 7.8 g·m-2·h-1. In addition, both mechanical properties and abrasion mass loss of studied medium Mn steel are compared with several metallic materials currently used in pump impeller of Yellow River.It was found that higher hardness leads to reduce erosion mass loss in the case of no occurrence of brittle macrocracking; when the materials undergo plastic deformation during scouring, ultimate tensile strength determines the anti-abrasion resistance; in the case of similar hardness, higher ductility and toughness may also improve abrasion resistance. Since the developed medium Mn steel has the better combination of tensile strength-work hardening ability-hardness-toughness than other materials currently used, it is expected to have a high potential of being used in pump impellor with prolonged life for the irrigation works of Yellow River

Effect of oscillation frequency on the mechanical properties and failure behaviors of laser beam welded 22MnB5 weld

Al–Si coated 22MnB5 steel is a lightweight material that helps significantly reduce vehicle weight and fuel consumption. In this article, the effect of different oscillation frequencies on the fraction of α-ferrite, the cross-sectional shape, microstructure and mechanical properties of laser welded Al–Si coated 22MnB5 steel was investigated. The results showed that after stamping, the fraction of α-ferrite in the fusion zone can be significantly reduced from 47.9% to 2.2% by oscillating laser beam welding compared to static laser beam welding with oscillation frequency and amplitude equal to zero. When the oscillating frequency was increased from 0 to 320 Hz, the cross-sectional shape of the weld changed from “X'' to “Y'', and the tensile strength and elongation of the welded joint was firstly increased and then decreased from the minimum value of (426.45HV, 1159.92 MPa, 1.14%) to the maximum value of (476.98HV, 1521.39 MPa and 2.76%). The formation of α-ferrite along the strip distribution near the upper surface of the fusion zone of static laser beam welding and oscillating laser beam welding after hot stamping, which led to stress concentration and eventual failure. Under the tensile-shear load, the cracks in the weld of static laser beam welding and oscillating laser beam welding were initiated on the massive α-ferrite location in the top surface of the fusion zone and expanded to the bottom of the weld

Influence of softening annealing on microstructural heredity and mechanical properties of medium-Mn steel

Softening annealing (SA) is often required for producing medium-Mn steels (MMS) as it lowers hardness so that they can be cold rolled to reduce thickness. The influences of different SA processes on the microstructural heredity during the processing route and the final tensile properties were studied. It was found that the SA process could either intensify or weaken the influence of the Mn segregation resulting from solidification on the subsequent microstructural evolution during the process, i.e., microstructural heredity. In the case when no SA was employed, both recrystallization and rapid growth of ferrite grains preceded the reverse austenitic transformation during the intercritical annealing (IA) in the Mn-lean regions, where very coarse ferrite grains were formed. This deteriorated ductility due to the propagation of cracking along the boundary of the coarse-grained and fine-grained regions. In contrast, SA at a sufficiently high temperature could dissolve cementite, producing uniformly distributed austenite grains. They transformed to martensite during cold rolling but were reborn during IA. As a result, ultrafine austenite and ferrite grains were uniformly distributed, which improved ductility significantly. This study hints at a new approach to altering the microstructural heredity resulting from the heterogeneous Mn distribution in MMS

Perforated Ground Plane Structures for RF and Wireless Components

10.1155/2013/709310International Journal of Antennas and Propagation201370931