Recent Trends of HIP Equipment Technology in Japan

The progress of HIP (Hot Isostatic Pressing) is discussed from both the historical viewpoint and its future potential. HIP is now recognized as a useful method to obtain products with isotropic properties and high density. It is used in the manufacture of high integrity castings, various PM products and ceramic components. Especially in Japan these resultant natures have attracted attention from ceramic researchers, because HIP can compensate for the lack of reliability due to residual porosity formed in the sintering stage. P/M High speed tool steel billets, alumina cutting tool inserts, soft ferrite for magnetic recording heads all have been produced by the HIP process. Research activities are now expanding into so-called nano-technology areas such as Si-wafer processing and nano-level sensors. Entering the 21st century, however, a sluggish economy and environmental friendliness are producing strong demand for further development of smaller and lighter products with higher mechanical or electronic properties. In addition to these, the requirement for the higher productivity to reduce processing cost is intensifying, thus the developmental works on HIP equipment technology are being focussed on the improvement of its productivity as well as application to novel processing areas.

Fundamental Study on the Super-Long-Period Active Isolation System

Since the Hanshin-Awaji Earthquake Disaster, the number of isolated structures has been greatly increased. The natural period of the isolation system is designed around 3 seconds, because predominate period of observed seismic waves is usually 0.1 to 1 second. However, relatively long period seismic waves have been observed in various earthquakes, and the resonance of long-period structures, such as high-rise buildings, during earthquakes have been reported at the same time. Therefore the natural period needs to be extended. When extending the natural period of the isolated structure using rubber bearings, its stiffness needs to be reduced. It is more difficult to extend the natural period of the isolation system than the conventional system because of its buckling problem. Therefore we propose a super-long-period active seismic isolation system as a new method for extending the natural period of the isolated structure. This system consists of rubber bearings and actuators. In this study, we designed a control system by using the model-matching-method. This is one of the classical control system design methods. We investigated the isolation performance by numerical analysis. In addition, we selected the optimal variables of transfer function using genetic algorithm.

Study on Estimation Method for Seismic Safety Margin of 3D Piping System With Degradation: Establishing Elasto-Plastic Analysis Model

The authors have proposed an analytical model by which they can simulate the experimental results of a piping system with full circumferential 48% thinning at an elbow or two elbows. A series of elasto-plastic analyses has been carried out in order to investigate the experimental behavior of the piping system. Dynamic analyses describe the ratcheting behavior and the average amplitude of the opening-closing displacement at elbows relatively well. And then static analyses describe ratcheting and ovaling of the cross section of pipes fairy well.

FE Predictions of Temperature Distributions in a Multipass Welded Piping Branch Junction

This contribution deals with the complex temperature profiles that are generated by the welding process in the intersection region of thick walled, cylinder-cylinder junctions. These affect material microstructure, mechanical properties and residual stresses. Knowledge of the thermal history and temperature distributions are thus critical in developing control schemes for acceptable residual stress distributions to improve in-service component behavior. A comprehensive study of 3D temperature distributions in a stainless steel tee branch junction during a multipass welding process is presented. A newly developed partitioning technique has been used to mesh the complex intersection areas of the welded junction. Various phenomena associated with welding, such as temperature dependent material properties, heat loss by convection and latent heat have been taken into consideration. The temperature distribution at various times after deposition of certain passes and the thermal cycles at various locations are reported. The results obtained in this study will be used for on-going and future analysis of residual stress distributions. The meshing technique and modeling method can also be applied to other curved, multipass welds in complex structures.

Nonlinear Finite Element Analysis of a Threaded Pipe Connection

For the past several years, USC has been involved in a major research project to study the seismic mitigation measures of nonstructural components in hospitals funded by the Federal Emergency Management Agency (FEMA). It was determined that piping was the one of the most critical components affecting the functionality of a hospital following an earthquake. Consequently, a substantial effort was spent on quantifying the behavior of typical piping components. During the loading of the threaded joint, it was common to hear a loud popping sound, followed by a small water leak. It was assumed that the sound and leakage were due to the sliding of the mating pipe threads. To confirm this theory, and to provide a tool to help understand the failure mode(s) for a wide class of threaded fittings, a detailed nonlinear finite element model was constructed using MSC/NASTRAN, and correlated to the measured failures. In this paper, a simplified model is presented first to demonstrate the modeling procedure and to help understand the sliding phenomenon. Next, a symmetric half 3D model was generated for modeling the physical experiments. It is shown that the finite element analysis (FEA) of the threaded connections captures the dominant mechanism that was observed in the experimental tests.

High Pressure Fatigue Testing of 160 KSI Yield Strength Stainless Steel Tubing

High pressure processes like water-jet cutting, hydroforming or LDPE production require high pressure tubing with nominal sizes of 2 to 90 mm for pressures of up to 4,000 bar. The most common materials for these applications are either cold drawn austenitic steels type 304 / 316 or low alloy martensitic steels from the A723 series. Recent developments in material technology made it possible to increase the yield strength of the cold drawn austenitic steel from 700 MPa to 1100 MPa maintaining high toughness values, even for relatively large tube sizes. This steel grade, referred to as “HP160” (nitrogen strengthened 21Cr 10Ni 3Mn 2.5Mo stainless steel), is now increasingly being utilised in the high pressure industry. In this paper the fatigue performance of HP160 under pulsating internal pressure will be compared to fatigue results from conventional steels. The results will also be compared with the requirements of the ASME high pressure code Section VIII Division 3.

Dynamic Analyses of a Metallic Sample in Sonic Infrared NDE Technique: Experimental and Computational Approach

Sonic IR is an emerging NDE technique being developed at the Wayne State University that has potential crack detectability both in metallic and non-metallic materials. The technique has applications in various sectors of NDE including aerospace, automotive, transportation, pressure vessel, and piping and manufacturing. Although it is established that friction caused by rubbing between the faying surfaces (i.e. tightly closed surfaces of closed surface cracks) or other material flaws under sonic load generates heat, the relationship of the quality and quantity of heat generation mechanics are not yet well known. In this paper a simple aluminum plate sample with generated cracks is studied through both experimentation and finite element (FE) modeling and simulation. The dynamics of Sonic IR for a simple metallic sample are analyzed with LS-DYNA3D finite element program. The FE analysis does support the frictional heat generation due to the rubbing of the faying surfaces of the crack faces. FE analysis also allows visualization of crack faces rubbing mode. The experiments show the infrared signal level as the indication of heat generation, captured in real time video frames. In FE simulation the energy plot at the crack interface is an indicator of heat generation and the energy plots are compared with the infrared signal plot. The results of varying test parameters in experiments as well as FE simulations are also discussed.

Application of a Knowledge-Based Information System for Life Extension of Steel Making Plant

In this paper, a knowledge-based information system for the plant operation of steel making company has been proposed. This system, which is named as K-VRS (Knowledge-based Virtual Reality System), provides a connection between ERP PM module and knowledge-based engineering methodologies, and thus, enables network-based highly effective PM process. While the virtual plant is used for the master of K-VRS, there are four expert modules attached; engineering document management module, real time lifetime estimation module, fitness for service module and risk-based inspection module. Each module provides engineering knowledge based evaluation and judgment for more effective PM. K-VRS provides collaborative and concurrent working environment to workers and relevant experts. The developed system is expected to play a great role for plant life extension.

Stress and Fracture Analysis of Ceramic Lined, Composite or Steel Jacketed Pressure Vessels

Stress and fracture analysis of ceramic-lined cannon pressure vessels is described, for a Si3N4 or SiC liner and A723 steel or carbon-epoxy jacket and with an initial residual interface pressure between liner and jacket. Room temperature stresses for a steel jacket over ceramic are similar to those for a carbon-epoxy jacket, but both radial and hoop jacket stresses can exceed typical carbon-epoxy strength values. Elevated temperature liner stresses are reduced for a carbon-epoxy jacket, due to the effective increase in interface pressure caused by differential thermal expansion. Critical crack size for brittle fracture is larger for Si3N4 than SiC due to lower liner stresses and higher fracture toughness with a Si3N4 liner.

Proposal for the Implementation of Elevated Temperature Design Fatigue Curve for 2-1/4Cr-1Mo-V and 3Cr-1Mo-V Steels

2-1/4Cr-1Mo-V and 3Cr-1Mo-V steels have been used extensively as materials for elevated temperature and high-pressure hydro-processing reactors. These steels have both of high strength at elevated temperature and high resistance against elevated temperature hydrogen attack due to the addition of vanadium. The operating temperature of these reactors is between 800 and 900deg.F. The fatigue evaluations of these reactors per ASME Sec. VIII Div.2 and Div.3 can’t be performed in spite of demand for fatigue analysis because the temperature limit of design fatigue curve in ASME Sec. VIII Div.2 and Div.3 for carbon and low alloy steels is 700deg.F. Results of load and strain controlled fatigue tests conducted over the temperature range from room temperature to 932deg.F (500deg.C) are reported for 2-1/4Cr-1Mo-V and 3Cr-1Mo-V steels. These data were compared with data for 2-1/4Cr-1Mo steels available from the literatures. The fatigue strength for a 2-1/4Cr-1Mo-V steel in high cycle region is higher than that for 2-1/4Cr-1Mo steels and in low cycle region is lower. The fatigue strength for a 3Cr-1Mo-V steel is almost same as that for 2-1/4Cr-1Mo-V steels. Therefore an elevated temperature design fatigue curve for 2-1/4Cr-1Mo-V and 3Cr-1Mo-V steels is newly proposed. It is found from the case study that the different fatigue life can be predicted by using different mean stress correction procedure.