Alloy Design for Enhancing the Fracture Resistance of Heat Treated High Pressure Die-Castings

2010 ◽  
Vol 654-656 ◽  
pp. 954-957 ◽  
Author(s):  
Roger N. Lumley ◽  
Maya Gershenzon ◽  
Dayalan R. Gunasegaram
Keyword(s):  
Heat Treatment ◽  
High Pressure ◽  
Fracture Resistance ◽  
Heat Treating ◽  
A380 Alloy ◽  
Conventional Aluminum Alloy ◽  
Heat Treated ◽  
Treatment Technologies ◽  
Die Castings ◽  
Dimensional Instability

Recently, heat treatment technologies have been developed by the CSIRO Light Metals Flagship in Australia that allow the 0.2% proof stress of conventional aluminum alloy high pressure diecastings (HPDC’s) to be more than doubled without encountering problems with blistering or dimensional instability [1,2]. A range of other properties may also be improved such as fatigue resistance, thermal conductivity and fracture resistance. However, the current commercial HPDC Al-Si-Cu alloys have not been developed to exploit heat treatment or to optimize these specific mechanical properties, and one potential limitation of heat treating HPDC’s is that fracture resistance may be reduced as strength is increased. The current paper presents the outcomes of a program aimed at developing highly castable, secondary Al-Si-Cu HPDC alloys which display significantly enhanced ductility and fracture resistance in both the as-cast and heat treated conditions. Kahn-type tear tests were conducted to compare the fracture resistance of the conventional A380 alloy with a selection of the newly developed compositions. A comparison has also been made with the current permanent mold cast aluminium alloys and it is shown that the new HPDC compositions typically display higher levels of both tensile properties and fracture resistance.

A Preliminary Evaluation on the Fracture Toughness of Heat Treated Aluminium High Pressure Diecastings

2008 ◽  
Vol 41-42 ◽  
pp. 141-146 ◽  
Author(s):  
Roger N. Lumley
Keyword(s):  
Heat Treatment ◽  
Fracture Toughness ◽  
High Pressure ◽  
Tensile Properties ◽  
Fracture Resistance ◽  
Heat Treating ◽  
Preliminary Evaluation ◽  
Sand Cast ◽  
Heat Treated ◽  
Die Castings

Until recently, the solution heat treatment of conventional aluminum high pressure die cast (HPDC) parts has been considered impractical because the high temperatures involved cause surface blistering and dimensional instability. Now, a new heat treatment procedure has been developed by the CSIRO Light Metals Flagship in Australia which avoids these problems and, in many cases, allows tensile properties such as 0.2% proof stress to be doubled with little change to ductility. This development has the potential to reduce costs by allowing existing HPDC parts to be re-designed to use less metal and still achieve performance requirements. One issue, however, is the possibility that heat treating die castings to increase tensile properties may have an adverse effect on fracture toughness. This paper reports preliminary results of Kahntype tear tests conducted to assess the fracture resistance of as-cast and heat treated HPDCs. Studies of the alloys A360, A380 and C380 have shown that T4 and underaged (UA) T6 tempers produce an optimal combination of fracture resistance and tear strength. Furthermore, the fracture properties compare well with permanent mold and sand cast aluminium alloys that have similar tensile properties.

Design of Secondary Alloy Compositions for High Performance Aluminium Pressure Diecastings

2011 ◽  
Vol 693 ◽  
pp. 247-255
Author(s):  
Roger Lumley
Keyword(s):  
Heat Treatment ◽  
High Pressure ◽  
High Performance ◽  
High Strength ◽  
Property Development ◽  
Cycle Times ◽  
Surface Finishes ◽  
Heat Treated ◽  
Dimensional Instability ◽  
Pressure Die Casting

High pressure die-casting (HPDC) is a widely used production technique for metal components that are required to have close dimensional tolerances and smooth surface finishes. Approximately 50% of the aluminium castings produced globally are manufactured by HPDC from secondary alloy and these are dominant in the automotive sector where they account for the majority of aluminium components present in each vehicle manufactured. Recently, it has been shown that industrially produced aluminium alloy high pressure diecastings (HPDC’s) can be successfully heat treated without encountering problems with surface blistering or dimensional instability. These processes may significantly improve the properties which develop from the alloys, thereby significantly increasing the scope of applications that may be realized. HPDC alloys however have not been developed specifically for heat treatment or the optimization of specific properties. In particular, recent work in Al-Si-Cu HPDC alloys has identified composition ranges of alloys for a) achieving yield strengths exceeding 400 MPa, b), rapid heat treatment that minimizes cost / cycle times, and c) high strength combined with elevated ductility levels. The role of alloying elements, composition limits and effects on mechanical property development are discussed.

Alloy Design for Heat Treatment of High Pressure Diecastings

2009 ◽  
Vol 618-619 ◽  
pp. 331-339 ◽  
Author(s):  
Roger N. Lumley ◽  
Maya Gershenzon ◽  
Dayalan R. Gunasegaram
Keyword(s):  
Heat Treatment ◽  
Yield Stress ◽  
Solution Treatment ◽  
High Strength ◽  
Artificial Ageing ◽  
Heat Treated ◽  
Treatment Technologies ◽  
Dimensional Instability ◽  
Treatment Step

Recently, heat treatment technologies have been developed by the CSIRO Light Metals Flagship in Australia that allow the yield stress in conventional aluminium HPDC’s to be more than doubled without encountering problems with blistering or dimensional instability. These procedures involve a severely truncated solution treatment step conducted at lower than normal temperatures followed by quenching and artificial ageing. Typically, heat treated HPDC’s may display increases to the yield stress of around 80 to 100%, but a range of other properties may also be improved such as fatigue resistance, thermal conductivity and fracture resistance for some tempers. However, the HPDC alloys currently used worldwide have not been developed specifically for heat treatment or the optimization of specific properties. In particular, recent work in Al-Si-Cu HPDC alloys has identified ranges of alloys specifically for achieving yield strengths exceeding 400 MPa, or for high strength combined with elevated ductility levels. The role of alloying elements, composition limits and effects on microstructure development are discussed.

scholarly journals Portable, non-destructive colorimetry and visible reflectance spectroscopy can accurately identify heat-treated South African silcrete

2021 ◽  
Author(s):  
John K. Murray ◽  
Simen Oestmo ◽  
Andrew M. Zipkin
Keyword(s):  
Heat Treatment ◽  
Visible Spectrum ◽  
Heat Treating ◽  
Reflectance Spectroscopy ◽  
Modern Human ◽  
Middle Stone Age ◽  
Majority Voting ◽  
K Nearest Neighbors ◽  
Heat Treated ◽  
Visible Reflectance

The objective of this study was to determine if visible reflectance spectroscopy and quantitative colorimetry represent viable approaches to classifying the heat treatment state of silcrete. Silcrete is a soil duricrust that has been used as toolstone since at least the Middle Stone Age. The ancient practice of heat treating silcrete prior to knapping is of considerable interest to paleolithic archaeologists because of its implications for early modern human complex cognition generally and the ability to manipulate the material properties of stone specifically. Here, we demonstrate that our quantitative, non-invasive, and portable approach to measuring color, used in conjunction with k-Nearest Neighbors “lazy” machine learning, is a highly promising method for heat treatment detection. Traditional, expert human analyst approaches typically rely upon subjective assessments of color and lustre and comparison to experimental reference collections. This strongly visual method can prove quite accurate, if difficult to reproduce between different analysts. It is thus surprising that until now, no published study has sought to exploit an instrumental approach to measuring color for classifying heat treatment state in silcrete. In this work, we measured percent reflectance for the visible spectrum (1018 variables) and tristimulus color values (CIEL*a*b*) in unheated and experimentally heat treated silcrete specimens from three sources in South Africa. k-NN classification proved highly effective with both the spectroscopy and colorimetry data sets. An important innovation was using the heat treatment state predicted by the k-NN model for the majority of replicate observations of a single specimen to predict the heat treatment state for the specimen overall. When this majority voting approach was applied to the 746 individual observations in this study, associated with 94 discrete silcrete flakes, both spectroscopy and colorimetry k-NN models yielded 0% test set misclassification rates at the specimen level.

Effect of heat treatment on results for biochemical analysis of plasma and serum.

1985 ◽  
Vol 31 (12) ◽  
pp. 2028-2030 ◽  
Author(s):  
I Houssein ◽  
H Wilcox ◽  
J Barron
Keyword(s):  
Heat Treatment ◽  
Biochemical Analysis ◽  
Immune Deficiency Syndrome ◽  
Heat Treating ◽  
Deficiency Syndrome ◽  
Serum Samples ◽  
Biochemical Tests ◽  
Heat Treated ◽  
Clinically Significant ◽  
Acquired Immune Deficiency

Abstract Incubation of serum and plasma samples at 56 degrees C for 30 min inactivates the HTLV-III virus. We assessed the effect of this procedure on results of routine biochemical tests by dividing samples of serum and plasma into two, heat-treating one while the other remained at room temperature. Samples were then analyzed in an SMA 16/60, an Astra-8, an Analox glucose analyzer, a Cobas Bio centrifugal analyzer, and manually for salicylate and acetaminophen (paracetamol). Most of the differences produced by heat treatment were not clinically significant, although heated samples proved unsuitable for use in assay of some commonly measured enzymes. Serum evidently is preferable to plasma for this procedure, and heat-treated serum samples can validly be used for most routine analyses. Thus this procedure makes safer the analysis of samples from patients with suspected or proven acquired immune deficiency syndrome (AIDS).

Problems Associated with Heat Treated Parts

2021 ◽  
pp. 307-325
Author(s):  
Jon L. Dossett
Keyword(s):  
Heat Treatment ◽  
Stainless Steel ◽  
Cold Working ◽  
Heat Treating ◽  
Heat Treatments ◽  
Quenching Media ◽  
Heat Treated ◽  
Nonferrous Alloys

Abstract This article introduces some of the general sources of heat treating problems with particular emphasis on problems caused by the actual heat treating process and the significant thermal and transformation stresses within a heat treated part. It addresses the design and material factors that cause a part to fail during heat treatment. The article discusses the problems associated with heating and furnaces, quenching media, quenching stresses, hardenability, tempering, carburizing, carbonitriding, and nitriding as well as potential stainless steel problems and problems associated with nonferrous heat treatments. The processes involved in cold working of certain ferrous and nonferrous alloys are also covered.

Effect of Heat Treatment on the DC Conductivity and Activity Energy of Li2O-Fe2O3-P2O5 Glasses

2007 ◽  
Vol 336-338 ◽  
pp. 1827-1828 ◽  
Author(s):  
Ji Yong Pan ◽  
Jiang Hong Gong
Keyword(s):  
Heat Treatment ◽  
Electrical Properties ◽  
Heat Treating ◽  
Iron Phosphate ◽  
Phosphate Glasses ◽  
Sample Heat ◽  
Heat Treated ◽  
Maximum Conductivity ◽  
Iron Phosphate Glasses ◽  
Activity Energy

Iron phosphate glasses with composition of 20Li2O-32Fe2O3-48P2O5 (in mol%) was prepared by melting, crushing and heat-treating process and the electrical properties were examined. It was found that the sample heat-treated at a temperature close to the glass transition temperature exhibit the maximum conductivity and the lowest activation energy, implying that heat-treatment may play an important role in the electrical properties of the glasses.

Failure analysis of heat treated HSLA wheel bolt steels

2010 ◽  
Vol 6 (3) ◽  
pp. 373-382
Author(s):  
Ali Nazari ◽  
Shadi Riahi
Keyword(s):  
Heat Treatment ◽  
Tensile Strength ◽  
Failure Analysis ◽  
Heat Treating ◽  
Boron Steel ◽  
Content Type ◽  
Heat Treated ◽  
Before And After ◽  
Molybdenum Steel ◽  
Optimum Heat

PurposeThe aims of this study is to analyze failure of two types of high‐strength low‐alloy (HSLA) steels which are used in wheel bolts 10.9 grade, boron steel and chromium‐molybdenum steel, before and after heat treatment.Design/methodology/approachThe optimum heat treatment to obtain the best tensile behavior was determined and Charpy impact and Rockwell hardness tests were performed on the two steel types before and after the optimum heat treating.FindingsFractographic studies show a ductile fracture for heat‐treated boron steel while indicate a semi‐brittle fracture for heat‐treated chromium‐molybdenum steel. Formation of a small boron carbide amount during heat treating of boron steel results in increment the bolt's tensile strength while the ductility did not changed significantly. In the other hand, formation of chromium and molybdenum carbides during heat treating of chromium‐molybdenum steel increased the bolt's tensile strength with a considerable reduction in the final ductility.Originality/valueThis paper evaluates failure analysis of HSLA wheel bolt steels and compares their microstructure before and after the loading regime.

The Evolution of Microstructure Due to Heat Treatment on Highly Porous Copper/Silver Systems

2007 ◽  
Author(s):  
Brian A. Murtha ◽  
Anil K. Kulkarni ◽  
Jogender Singh
Keyword(s):  
Heat Treatment ◽  
Particle Surface ◽  
Heat Treating ◽  
Furnace Temperature ◽  
Particle Surface Area ◽  
Porous Copper ◽  
Heat Treated ◽  
Powdered Copper ◽  
Evolution Of Microstructure ◽  
Highly Porous

The sintering phenomenon is examined in highly porous materials by first cold pressing powdered copper and silver and separately heat treating them in an un-pressurized furnace. The initial microstructure prior to heat treatment as compared to that after heat treatment showed similar characteristics regardless of the material or powder geometry. However, after heat treatment, there are significantly different microstructures among samples. The microstructures depend on the maximum furnace temperature, the particle geometry, material composition, and the particle surface area. While the microstructures change significantly, there is no change in porosity between pre- and post-heat treated samples.

Microstructure and Phase Transformation of Super-High Pressure Mg-Li Alloy

2015 ◽  
Vol 816 ◽  
pp. 375-380 ◽  
Author(s):  
Qiu Ming Peng ◽  
Hui Fu ◽  
Yan An Wang ◽  
Hui Li
Keyword(s):  
High Pressure ◽  
Phase Transformation ◽  
Heat Treating ◽  
Dendritic Morphology ◽  
Metallic Materials ◽  
Cast Sample ◽  
Temperature Range ◽  
Electronic Distribution ◽  
Heat Treated ◽  
Dislocation Movement

Super-high pressure (SHP) changes crystal structure and electronic distribution of metallic materials, which plays an important role in properties. Herein, a duplex Mg-7%wt.Li alloy was heat-treated under SHP (2 GPa) by cubic-anvil large-volume press with six rams for 2 h in the temperature range of 450~1350 °C. Microstructure, phase transformation behavior and mechanical properties were examined. Compared with the as-cast sample, the SHP samples after heat-treating from 450 °C to 750 °C under 2 GPa were composed of twinning in addition to duplex structure. Comparatively, the samples treated between 1050 °C and 1350 °C exhibit typical dendritic morphology. Phase transformation from Li3Mg7 phase or Li0.92Mg4.08 phase to Li3Mg17 phase occurred during the whole investigated temperature range, in which only the Li3Mg17 phase maintained when the temperature exceeds 1050 °C. The microhardness of the sample prepared at 750 °C under 2 GPa was 73.15HV, which is 1.5 times higher than that of the as-cast one. The improved microhardness is mainly attributed to the formation of nanosized twins during SHP treatment. These fine twins effectively prohibit the dislocation movement during deformation. It reveals the SHP is an effective approach to prepare high performation Mg alloys.

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