Friction Coefficient Identification in Roll Forming Processes

The roll forming process is a very interesting process for the production of profile shaped parts because of its high production rate, low investment and efficient use of the material. However, as in most of the manufacturing processes, the set up of the machine is very important for the quality of the profiles to be manufactured being the traditionally used trial and error method high time and scrap consuming. Within the set up, one of the most important variables to be defined is the right gap or distance between the upper and the lower roll at each station. This gap can lead to, or avoid, the appearance of geometrical errors such as differences in springback effect or longitudinal bow of the final profile. Furthermore, to find the correct gap between the rolls,a traditional tedious and costly work must be made based on a trial and error methodology. Different sensor based methodologies have already been implemented successfully in other forming processes. The present work aims at evaluating if force and torque measurements are a viable solution to decrease the roll forming process set-up time. This way, the effect of the gap for three different materials, a DC01, DP600 and MS1200 steel, has been analyzed. For this purpose, force and torque measurement together with final geometry measurements have been made at different gap configurations. A correlation between the profile quality and the process variables has been carried out in order to identify the influence of the gap at the setting up of the machine.

Material Efficiency and Energy Use

High strength and corrosion resistant nickel alloys Hastelloy C-86 ® (UNS N06686) and Hastelloy C-22HS ® (UNS N07022) are currently being evaluated and/ or used by the Navy for current and future bolting applications where both high strength, toughness, ductility along with excellent resistance to corrosion and hydrogen embrittlement are required. This includes present and new ship design. The 686 alloy is currently into final stages of data gathering and mil spec preparation. Alloy 686 is a solid solution nickel base alloy obtaining it’s strength through cold work. The C-22HS alloy was recently introduced for applications requiring both corrosion resistance and high strength. Being a C-type alloy (Ni-Cr-Mo), C- 22HS has excellent corrosion resistance in both reducing and oxidizing environments. The alloy is capable of being age-hardened to effectively double the yield strength over other Ctype alloys. The C-22HS alloy has generated interest in the oil & gas industry due to its resistance to sour brine environments. C-22HS is being included in NACE MR0175/ISO 15156 at NACE Level VII (highest severity), exhibiting resistance to severe sour brine environments. Properties of the new alloy relevant to marine corrosion and Navy fastener applications are presented. This material has also been shown to be resistant to hydrogen embrittlement in marine and other severe environments, exhibiting potential for corrosion immunity. Efforts in developing alternate processing routes for C-22HS alloy for very high strength applications are detailed. The high strength of C-22HS alloy is imparted through the formation of Long Range Ordering (LRO) domains of Ni2(Cr, Mo) which develop during a two-step age-hardening treatment. In standard C-22HS alloy, the formation of the LRO domains nearly doubling of the room temperature yield strength up to values around 100 ksi. The yield strengths of the as-cold worked bars ranged from 191 to 205 ksi (1317 to 1413 MPa), and the cold-worked + age-hardened bars ranged from 199 to 206 ksi (1372 to 1420 MPa). In these material conditions, C-22HS also exhibits excellent ductility and fracture toughness of _150 ft-lbs (_203 J) from -300ºF to +550ºF (-149 to 288°C). The C - 22HS alloy is presently being tested for Navy Subsafe high strength fastener approval. An important feature of the C-22HS alloy in the age-hardened condition is that the alloy retains excellent corrosion resistance. Both alloys C-86 and C-22HS have excellent potential for all marine and military applications where excellent strength, toughness and corrosion resistance are required. In addition to the nickel alloy just discussed, NITRONIC® 50HS (UNS S20910) Stainless Steel provides a combination of corrosion resistance and strength not found in any other commercial material available in its price range. As a result, the use of this alloy for boat shafting is significantly increasing for commercial and naval shipping. Superior corrosion resistance, high yield strength, exceptionally low magnetic permeability and outstanding cryogenic properties define this alloy usefulness for boat shafting.

A comprehensive understanding of the relationship between the hardness and the elastic and plastic properties for a wide range of materials is obtained by analysing the hardness characteristics (that are predicted by experimentally verified indentation analyses) of over 9000 distinct combinations of material properties that represent isotropic, homogeneous, power-law hardening metallic materials. Finite element analysis has been used to develop the indentation algorithms that provide the relationships between the elastic and plastic properties of the indented material and its indentation hardness. Based on computational analysis and virtual testing, the following observations are made. The hardness (H) of a material tends to increase with an increase in the elastic modulus (E), yield strength (σy) and the strain-hardening exponent (n). Several materials with different combinations of elastic and plastic properties can exhibit identical true hardness (for a particular indenter geometry/apex angle). In general, combinations of materials that exhibit relatively low elastic modulus and high yield strength or strain-hardening exponents and those that exhibit relatively high elastic modulus and low yield strength or strain-hardening exponents exhibit similar hardness properties. Depending on the strain-hardening characteristics of the indented material, (i.e. n = 0 or ), the ratio H/σy ranges, respectively, from 2.2 to 2.6 or 2 to 20 (for indentations with a cone angle of 70.3°). The materials that have lower σy/E and higher n exhibit higher H/σy ratios. The commonly invoked relationship between hardness and the yield strength, i.e. H ≈ 3σy, is not generally valid or applicable for all power-law hardening materials. The indentation hardness of a power law hardening material can be taken as following the relationship H ≈ (2.1–2.8)σr where σr is the representative stress based on Tabor’s representative strain for a wide range of materials.

The first production lot of 50 units of metal matrix composite mirrors for the Leopard I tank fire control system was recently completed by Optical Corporation of America (OCA), Garden Grove, California. The mirror substrates were finish machined from forgings of Optical Grade SXATM metal matrix composite manufactured by Advanced Composite Materials Corporation (ACMC), Greer, South Carolina. Use of forgings rather than hot pressed billet yields more efficient use of material and reduces machining time, resulting in lower cost. The mirrors were fabricated by a process sequence of machining, thermal stabilization, electroless nickel plating, polishing, and coating with a high efficiency, laser damage-resistant optical coating. The mirrors are used in the fire control system for a day channel (direct view) and near infrared (CCD), a muzzle reference system laser transceiver, a laser range finder, and an infrared thermal imaging system. SXA composite was chosen over competitive mirror materials (glass and beryllium) because of its high specific strength and stiffness, good stability, and moderate machining cost. The mirrors exhibit excellent stability and optical performance. Field trials of prototype mirrors in fire control systems have proven successful.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Microstructural evolution and mechanical behavior of metastable β-type Ti–25Nb–2Mo–4Sn alloy with high strength and low modulusMicrostructural evolution and mechanical behavior of metastable β-type Ti–25Nb–2Mo–4Sn alloy with high strength and low modulusretain-->

Design rules to develop solute lean α+β titanium alloys exhibiting high work-hardening by reorientation induced plasticity

HASTELLOY® alloys C-86 and C-22HS are currently being used or evaluated by the Navy bolting applications where both high strength, toughness, ductility, resistance to corrosion and hydrogen embrittlement are required. Alloys C-86 and C-22HS have been used in severe applications that require both corrosion resistance and high strength and C-22HS has properties applicable to cryogenic service. Alloy C-22HS is included in NACE MR0175/ISO 15156 exhibiting resistance to extremely severe corrosive environments. Properties of these alloys relevant to marine corrosion and Navy fastener applications are presented. The alloy C-22HS yield strength ranges from 191 to 205 ksi (1317 to 1413 MPa). AlloyC-22HS also exhibits excellent ductility and fracture toughness of ≥150 ft-lbs (≥203 J) from -300ºF to +550ºF (-149 to 288°C). Superior corrosion resistance, high yield strength, low magnetic permeability and outstanding cryogenic properties define C-22HS alloy usefulness. NITRONIC® 50HS (UNS S20910) Stainless Steel provides a combination of corrosion resistance and strength not found in any other commercial material available in its price range. As a result, the use of this alloy for boat shafting is significantly increasing for commercial and naval shipping. NITRONIC 50HS is currently used by the USCG for shafting on the Fast Response Cutter.

A number of heavy oil and oil sand reservoirs in Alberta have been successfully produced by natural depletion at rates far in excess of the predictions based on radial Darcy flow. Production rates can exceed 20 m3/d and con be maintained at such a high level for several years. What exactly causes the high primary production rates is not known, but several mechanisms on the primary production of heavy oil and bitumen have been proposed by various authors. These include solution gas drive, influx of bottomwater, sand production, wormholes, fractures and channels. Laboratory measurements which have been reported on the rheological properties of bitumen indicate that at low temperatures (e.g. 20 °Cj a mixture of bitumen or heavy oil with a small amount of sand behaves as a non-Newtonian fluid. The flow characteristics of a non Newtonian fluid in a reservoir and their effects on the primary production of heavy oil have been investigated in this study using ana/ysica/ solutions of the diffusivity equation. It was found that di/atant (shear thickening) effects can provide an explanation for low apparent viscosities at a distance from the wellbore where shear rates are low. This mechanism is consistent with the pressure buildup test results and with field production data where high production rates can be sustained over an extended period of time. Introduction A number of heavy oil and oil sand reservoirs in Alberta and Saskatchewan have been successfully produced by natural depletion. Primary recovery at the Lloydminster heavy oil deposit, which began over 40 years ago, has been significantly higher than the predictions based on radical Darcy flow. The heavy oil deposits in this area are relatively thin (3 m to 6 m) and occurring at depths from 300 m to 1000 m. The formations consist of unconsolidated sands with a relatively high porosity (29% to 35%) and high permeability (3500 mD). The oil gravity is quite low ranging from 10 to 20 degrees API with an oil viscosity of 400 mPa.s to 2000 mPa.s at initial reservoir conditions. Since 1985, Amoco have been producing significant amounts of bitumen from the Lindbergh Elk Point(1) area on primary production. The Clearwater formation at this location is 25 m to 30 m thick and consists of a moderately well sorted sand. The bitumen has a gravity of about 12 degrees API and a very high viscosity of 60 000 mPa.s at reservoir conditions (3900 kPa and 2O °C). The primary production rates average 15 m3/day 00 20 m3/day for over 3 years. These production rates are greater than can be predicted with radial Darcy flow calculations by a factor of more than 30. Potential Mechanisms It is not known what exactly causes these high primary production rates but a number of potential mechanisms have been suggested. in the literature: solution gas drive; influx of bottomwater; sand production; wormholes, fractures and channels; and rock compressibility. Smith(2) suggested that a possible production mechanism could be solution gas drive which was assisted occasionally by the influx of water.

The current study was carried out to evaluate the quantity and quality of rural domestic waste generation and to identify the factors affecting it in rural areas of Khodabandeh county in Zanjan Province, Iran. Waste samplings consisted of 318 rural households in 11 villages. In order to evaluate the quality and quantity of the rural domestic waste, waste production was classified into 12 groups and 2 main groups of organic waste and solid waste. Moreover, kriging interpolation technique in ARC-GIS software was used to evaluate the spatial distribution of the generated domestic waste and ultimately multiple regression analysis was used to evaluate the factors affecting the generation of domestic waste. The results of this study showed that the average waste generated by each person was 0.588 kilograms per day. with the share of organic waste generated by each person being 0.409 kilograms per day and the share of solid waste generated by each person being 0.179 kilograms per day. The results from spatial distribution of waste generation showed a certain pattern in three groups and a higher rate of waste generation in the northern and northwestern parts, especially in the subdistrict. The results of multiple regression analysis showed that the households’ income, assets, age, and personal attitude are respectively the most important variables affecting waste generation. The housholds’ attitude and indigenous knowledge on efficient use of materials are also the key factors which can help reducing waste generation.

A steel–concrete composite wall with boundary elements of steel U-section was developed for high structural performance and efficient use of materials. Cyclic lateral loading tests were performed on the proposed walls to investigate the flexural and shear performances. The test parameters included the failure mode of specimens, type of boundary reinforcement, sectional area of steel U-sections, horizontal web reinforcement ratio, and wall thickness. In the flexural yielding specimens, the flexural strengths of the proposed walls were equivalent to those of conventional reinforced concrete (RC) walls with boundary elements of vertical rebars, even though the yield strength of steel plates was 24% less than that of rebars. Further, the use of steel U-sections increased displacement ductility and energy dissipation, providing lateral confinement to the boundary concrete and restraining shear cracking and sliding. In the shear failure-mode specimens, the use of steel U-sections increased the diagonal tension-shear strength of walls. Thus, the shear strength of the composite walls was greater than that of conventional RC walls. The existing design method of JGJ 138 reasonably predicted the shear strength of the proposed composite walls, considering the contribution of boundary steel U-sections.

A novel AlMoNbHfTi refractory high-entropy alloy with superior ductility

Microstructure evolution and strengthening mechanism of FeCo-1.5V0.5Nb0.4 W soft magnetic alloy rolled strip with high yield strength and low coercivity

Improving local stability of aluminium profile with low-modulus stiffeners: Experimental and numerical web buckling analysis

Material efficiency: An economic perspective