High Strength Stainless Steel Research Articles

Mechanical Properties of a “Simple Panel Structure” Manufactured of an Ultra High Strength Stainless Steel

Corrugated core panels contain a formed, corrugated core bonded between two skin sheets. These panels are typically used in applications, where a low weight is required with integrity in stiffness. This paper demonstrates the mechanical properties of a simple panel structure (SPS), constructed using strips of work-hardened, austenitic stainless steel (ASS) grade 1.4310 (type 301) with the yield strength (YS) of ~1200 MPa. The 0.5 mm thick strips were formed into a C-shape and subsequently laser welded together by lap joints to form a SPS. The thickness of the SPS was 50 mm. The bending tests for the SPS were carried out transverse and 45-degrees related to the orientation of the web sheet. The results showed that the SPS, as loaded in the transverse direction, has about the same bending stiffness prior yielding as that of the previously tested 6 mm thick, low carbon S355 plain steel sheets, but the SPS is three times lighter than 6mm thick plain steel sheet. Compared with a corrugated core panel made of an annealed ferritic stainless steel (SS-panel) with the YS ~ 250 MPa, the weight of the both panels are roughly the same, but the bending resistance of the SPS is 45% higher. Experimental tests also verified that the benefit in the stiffness is quickly reduced if the load direction differs from transverse. In the 45-degrees loading direction, the SPS and the SS-panel had almost the same bending strength. On the other hand, the SPS and the SS-panel stiffnesses are much better than that of the carbon steel (the YS ~ 300 MPa) panel (CS-panel) in the both loading directions – the SPS being twice as stiff as the CS-panel.

Springback behaviors of high strength stainless steel tube after numerical control rotary draw bending

Taking the 21-6-9 (0Cr21Ni6Mn9N) high strength stainless steel tube (HSSST) of 15.88 mm × 0.84mm (diameter D × wall thickness t) as the objective, a three dimensional (3D) elastic plastic finite element (FE) model of the whole process of the 21-6-9 HSSST in numerical control (NC) rotary draw bending was established based on ABAQUS explicit/implicit code, and its reliability was validated. Then, the effects of process parameters on springback of the 21-6-9 HSSST in NC rotary draw bending were studied using the FE simulation based on orthogonal test. The results show that the effects of process parameters on springback angle and radius form high to low are the clearance between tube and wiper die Cw, mandrel extension length e, clearance between tube and mandrel Cm, friction coefficient between tube and wiper die fw, clearance between tube and pressure die Cp, friction coefficient between tube and bending die fb, friction coefficient between tube and pressure die fp, friction coefficient between tube and mandrel fm, clearance between tube and bending die Cb, bending speed ω, push assistant speed of pressure die Vp and e, Cw, Cm, fb, fw, Cb, fm, ω, Cp, fp, Vp, respectively. Springback angle and radius decrease with the increase of Cw, e or decrease of Cm, fb, fw, fm, Cb, while the Cp, fb, Vp and ω have no obvious influence on springback.

Investigation of Materials and Welds for the Precompression Structure of the ITER Central Solenoid

The central solenoid (CS) is the backbone of the ITER magnet system. It consists of six independent coils held together by a vertical precompression structure that must react to tensile loads and provide sufficient preload to maintain coil-to-coil contact during all stages of plasma operation. Material selection and specifications applicable to the structural components of the precompression structure are particularly demanding. These include large forgings manufactured from a high-strength austenitic stainless steel (FXM-19) with a stringent specification in terms of microstructure and maximum allowed magnetic permeability. Stringent requirements are also imposed on all welded joints. In particular, the attachment welds of the cooling pipes to the structure are subject to challenging restrictions in terms of weld imperfections and geometry. They must induce limited distortion of the components and are submitted to inspections carried out in accordance with the most severe acceptance levels of applicable national and international standards. The results of a campaign of tests covering nondestructive and destructive evaluation of samples from different components and welds are summarized in this paper, particularly focusing on the quality achieved at the microstructural and macrostructural level. The influence of the microstructure on the final properties and on the inspectability of the material by nondestructive examinations is also discussed.

ПОВЫШЕНИЕ ЭФФЕКТИВНОСТИ ФРЕЗЕРОВАНИЯ КРУПНОГАБАРИНЫХ ДЕТАЛЕЙ СИЛОВОГО НАБОРА ЛЕТАТЕЛЬНЫХ АППАРАТОВ

The PURPOSE of the paper is to improve the efficiency of milling of large-size parts of panel-, beam-, spar-, frame-type made of high-strength materials on CNC machine-tools. METHODS. The study employs experimental methods to study the issues of milling modes intensification. RESULTS AND THEIR DISCUSSION. The study has been given to the cutting properties of modern tool materials produced domestically for milling high-strength stainless steels, titanium and aluminium alloys. CONCLUSIONS. Application of hard alloys of brands ВП322 and ВРК15 in the designs of single-purpose and special cutters intensifies milling modes by 1.3-2.5 times when machining large-size parts from titanium alloys and high-strength stainless steels. Hard alloy ВК8 intensifies the removal of metal by 3-5 times as compared with the tool made of high-speed steel when milling parts from aluminium alloys.

Fatigue Properties of Ultra-Fine Grain Austenitic Stainless Steel and the Effect of Hydrogen

The fatigue properties of ultra-fine grain austenitic steel (UFG16-10), which has a 1 μm average grain size, were studied as part of the project aimed at the development of high-strength low-cost stainless steels for hydrogen service. The fatigue properties of the UFG16-10 were compared with that of a coarse grain material with the same chemical composition (CG16-10) and two kinds of commercial steels, JIS SUS316 and JIS SUH660. The fatigue strength of the UFG16-10 was 2.8 times higher than that of the CG16-10. The effect of hydrogen on the fatigue limit of the UFG16-10 was not significant. However, the fatigue life of the UFG16-10 was reduced by hydrogen in the short life regime. In the fatigue crack growth test, the UFG16-10 showed a good crack growth resistance that was equivalent to that of the SUH660 and significantly higher than that of the SUS316. However, the crack growth rate was significantly accelerated by hydrogen. The cause of the hydrogen-assisted fatigue crack growth of the UFG16-10 was transformation of the microstructure at the crack tip from austenite to strain-induced martensite. This was also the cause of the reduced fatigue life of the hydrogen-charged UFG16-10.

Fatigue Strength Property of High-strength Martensitic Stainless Steel in Petrol Environment

Fatigue Strength Property of High-strength Martensitic Stainless Steel in Petrol Environment

耐加工脆性と高サイクル疲労耐久性を有するハプティックデバイス用超高強度薄鋼板の開発

耐加工脆性と高サイクル疲労耐久性を有するハプティックデバイス用超高強度薄鋼板の開発

Sub-Zero Temperature Effect on Impact Properties of 17-4PH Stainless Steel Processed by Selective Laser Melting

The Selective Laser Melting (SLM) process has been proved as the most effective method among Additive Manufacturing (AM) technologies to produce hard, dense and strong metallic structures with intricate shapes and profiles from wide range of metallic alloys. The SLM generated structures from 17-4PH stainless steel high strength alloys involve layer by layer building up through laser melting of successively deposited powder layers. Therefore, the mechanical properties of such structures need to be thoroughly checked and investigated before putting these materials to practical applications. This research mainly investigates the cryogenic impact properties of SLM generated 17-4PH specimen. These characteristics are very important in applications requiring high strength customized structures that could maintain their mechanical properties at sub-zero temperatures. The experimental analysis proves that SLM is a very reliable technology to produce high strength metallic structures and these specimens can function efficiently in extreme conditions.

A Reliable and Efficient Approach to Numerically Controlled Programming Optimization for Multiple Largest Tools Cutting Blisks Patch by Patch in the Blisks' Four-Axis Rough Machining

As an important component of gas turbine engines, a blisk (or an axial compressor) is complex in shape. The pressure and suction surfaces of the blisk blades are designed with free-form surfaces, and the space (or the channel) between two adjacent blades varies significantly. Thus, some blade patches can be machined with large-diameter cutters, and some patches have to be cut with small-diameter cutters. Usually, the blisk's material is high-strength stainless steel, titanium alloy, or difficult-to-cut material. The cutting force and temperature in roughing the blisks are high, and thus, the machine tool should be rigid and the cutters should be as large as possible. Therefore, the best industrial practice of rough-machining the blisks is to use multiple largest solid and indexable end-mills to cut them patch by patch on a four-axis computer numerically controlled (CNC) machine. The reasons are (a) four-axis CNC machines are more rigid than five-axis CNC machines, (b) multiple largest cutters are used for higher cutting speeds and feed rates and for less machining time and longer tool life, and (c) if indexable end-mills can be used, the tooling costs are further reduced. For the blisk finishing, a small cutter is often used on a five-axis CNC machine, which is not a topic of this work. However, due to complex shape of the blades, it is quite difficult to automatically optimize the blade surface partition so that each surface patch can be cut with a largest cutter in four-axis blisk rough machining. In the conventional way, numerically controlled (NC) programmers often employ small-diameter solid end-mills and plan their paths to cut the blades layer by layer in four-axis milling. Unfortunately, the machining efficiency of this way is low, and the end-mills wear out quickly. This work establishes a theoretical and completed solution. A simplified optimization model of the largest allowable diameter of the theoretical cutter at a cutter contact (CC) point is established, and an efficient and reliable solver is proposed. The blade surfaces are automated partitioned for largest cutters to the surfaces patch by patch in four-axis rough machining. This approach is efficient and reliable, and it is viable in theory and practical in industry.

Bond of Steel Bars to Masonry Mortar Joints: Test Results and Analytical Modelling

In this paper, the preliminary results of a series of pull-out tests conducted on mortar cylinders with embedded bars are presented. The bars are made of high strength stainless steel and are of helical shape to increase mechanical interlocking with the surrounding mortar. Usually, such bars are employed in situ to realize structural repointing in the case of fair-faced masonry walls. To this aim, they are inserted in the mortar bed joints of masonry for providing tensile strength to the walls and with the function of crack stitching. The aim of the present experimental tests is to determine the bond-slip relationship for bars embedded in masonry. Firstly, pull-out tests are conducted on mortar cylinders considering different embedded lengths of the bars. Further tests are on-going on masonry specimens with bars embedded in the mortar joints. An analytical investigation is also carried out for the interpretation of the pull-out test results.

Failures of high strength stainless steel bridge roller bearings: A review

With the innovation of elastomeric bearings in the mid-1950s steel bearings lost their interest and significance both in research and development and subsequently even in application. Steel bearings were gradually abandoned in bridges, followed by the technical literature and design standards. However, a great number of steel bearings remain today in service world-wide and will pose their particular challenges in the future. To the author’s knowledge, just in Sweden, high strength stainless steel bearings still exist in no less than some 650 bridges. In recent years, a large number of such bearings have failed with an alarmingly high frequency in Sweden during a period of six to twenty years after installation making them a serious maintenance cost issue.After a brief summary of the history of high strength stainless steel bearings, the paper reviews service experience of such bearings in Sweden and elsewhere. Accompanying finite element analyses were performed in order to gain insight into the likely failure mechanism. Finally, this comprehensive review leads to a conclusion that identifies the causes of the failures occurred and makes some recommendations.Although previous investigations of the stainless steel bearings have not been able to clearly identify the cause(s) of the failures occurred, it is found that the failures primarily occurred due to initiation of cracks through stress corrosion cracking followed by fatigue crack growth requiring a certain stress range and a sufficiently large number of cycles until final failure ensued through sudden and instable fracture after fatigue growth to a critical crack size.

Structural Performance of Prestressed Concrete Bridge Piles Using Duplex Stainless Steel Strands

AbstractThe use of duplex high-strength stainless steel (HSSS) Grade 2205 prestressing strand and austenitic stainless steel (SS) Grade 304 spiral wire reinforcement is proposed for reinforcing pre...

On aging of high-strength stainless steel 08Cr15Ni5Cu2Ti

Based on our results and the results of the experimental studies previously conducted by other researchers, the analysis has been made of the influence of remelting methods on the character of the formation of the level of the impact strength KCU and its component KCV at aging of steel 08Cr15Ni5Cu2Ti prepared by two methods of remelting. The results of studying the influence of the remelting methods, heat treatment modes and impurity cleanness of steels on the level of KCU and the degree of its decrease at the temperatures of age hardening are presented. The factors causing the difference in the structure and phase composition in the steel formed by different remelting methods are established. The temperature range in which a significant decrease in KCU takes place has been determined. The hypothesis is offered about the role of interstitial impurities in the KCU decrease at aging.

高圧水素用高強度ステンレス鋼の溶接性

高圧水素用高強度ステンレス鋼の溶接性

Fatigue methodology for life predictions for the wheel-rail contact area in large offshore turret bearings

The present report presents a fatigue life prediction method for large roller bearings applied in the turret turn table for large loading buoy units. The contact points between wheel and rail in these bearings are subjected to a multi-axial fluctuating stress situation and both surface wear and fatigue cracking may occur. A methodology based on the Dang Van fatigue criterion is adopted. The criterion is based on an equivalent stress defined as a combination of the fluctuation of the shear stress from its mean value at a critical plane and the associated hydrostatic stress at the given time. The present work is supporting the theoretical model by extensive laboratory testing. Both full scale testing of wheel on rail and small scale testing for characterizing the steel material are carried out. An experimental program was carried out with the high strength stainless steel S165M. The Dang Van stress concept is applied in combination with the Random Fatigue Limit Method (RFLM) for life data analyses. This approach gives the opportunity to include both finite lives and the run-outs in a rational manner without any presumption of the existence of a fatigue limit in advance of the data. This gives a non-linear S-N curve for a log-log scale in the very high cycle regime close to the fatigue limit. It is demonstrated how the scatter in fatigue limit decreases when the Dang Van stress concept is applied and that the fatigue limit is occurring beyond 107 cycles. KEYWORDS. Dang Van criterion; Random Fatigue Limit Method; Rolling Contact Fatigue.

URANUS B64

Abstract Uranus B64 is a nonmagnetic high strength stainless steel. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness and fatigue. It also includes information on low temperature performance, corrosion resistance, and surface qualities as well as forming, heat treating, and joining. Filing Code: SS-1253. Producer or source: Industeel USA, LLC. See also Alloy Digest SS-1218, July 2015.

The Reticulatus method for shear strengthening of fair-faced masonry

This paper presents the results of several experimental campaigns recently carried out by the authors and devoted to the investigation of the mechanical performance of wall panels strengthened by applying repointing mortar and high strength stainless steel or composite cords. The reinforcement system, known as Reticulatus, allows the reinforcement of regular and irregular-shape masonry walls, when the fair-faced aspect must be kept. In the perspective of using this reinforcement method, this article summarizes the research that has been done so far, presenting new original test results and discussing the design procedures. Twenty-two square wall panels were loaded in their plane by means of a single point load acting through the panel’s diagonal. Experimental results are presented for four types of cord reinforcement using matched samples, reinforced and not. Increases in shear strength from 15 to 170 % were achieved for the strengthened panels. Each wall panel was loaded well into the lateral post-elastic regime and then unloaded. Experimental results were in good agreement with predictions from simple models which assume the wall panels to behave like a plate, neglecting the contribution of the repointing mortar, and accounting for the non-linear behavior of the masonry.

Structural design of cold-formed stainless steel tubular X- and T-joints at elevated temperatures

This paper presents a numerical parametric study on ultimate strength of cold-formed stainless steel tubular X- and T-joints at elevated temperatures. Extensive numerical simulations were carried out on SHS, RHS and CHS tubular X- and T-joints subjected to brace axial compression at different elevated temperatures ranging from 22 to 760°C. A wide range of geometric parameters and chord preload ratios was considered. The material properties of duplex, high strength austenitic and normal strength stainless steel (AISI 304) were carefully incorporated in the finite element models. The joint strength reduction was compared with the reduction factors of yield stress and elastic modulus of stainless steel materials at elevated temperatures. A unified equation for predicting ultimate strength of X- and T-joints at elevated temperatures was proposed by introducing a temperature factor. The statistical analysis shows that the proposed strength equation is reliable and accurate.

An Approximate Analysis of the Inner Wall Loading of a Bimetallic Camera Shell of Reusable Rocket Engine

В различных технических устройствах в качестве конструктивных элементов достаточно широко используют биметаллические оболочки. Характерным примером применения биметаллических оболочек является конструкция камеры сгорания жидкостного ракетного двигателя (ЖРД). В процессе работы ЖРД оболочка камеры сгорания подвержена интенсивным тепловым и механическим воздействиям, что приводит к необходимости ее охлаждения. Охлаждающий тракт оболочки образован зазором между ее внутренней и наружной стенками, скрепленными между собой гофрированными проставками или фрезерованными ребрами. Наружная стенка выполняет роль силового элемента оболочки, а внутренняя стенка непосредственно контактирует с высокотемпературными продуктами сгорания и подвержена интенсивному нагреву. Различие функций стенок оболочки вызывает необходимость их изготовления из разных материалов с различающимися теплофизическими и механическими характеристиками.

Retraction Statement: Stress corrosion cracking of high strength stainless steels for use as strand in prestressed marine environment concrete construction

The above article, published online on 10 April 2015 in Wiley Online Library (wileyonlinelibrary.com), and in volume 66, pp. 1269–1278, has been retracted by agreement between the authors, the journal Editors in Chief, Jürgen Mietz, and Wiley‐VCH Verlag GmbH & Co. KGaA. The retraction has been agreed due to substantial overlap with a previously published paper, and without consultation of the co‐authors of that publication: ‘Investigation of Stress Corrosion Cracking Susceptibility of High Strength Stainless Steels for Use as Strand Material in Prestressed Concrete Construction in a Marine Environment’, J. Fernandez, A. A. Sagüés and G. Mullins, Paper No.2686, 15 pp., Corrosion 2013, NACE International, Houston, 2013.ReferencesFernandez, J. (2015), Stress corrosion cracking of high strength stainless steels for use as strand in prestressed marine environment concrete construction. Materials andCorrosion, 66: 1269–1278. doi: 10.1002/maco.201408190