Cost-effective heat-treatment of aerospace fabrications

2014 ◽  
Vol 2 ◽  
pp. 345-352 ◽  
Author(s):  
Cristina Marinela Olarescu ◽  
Mihaela Campean

Heat treatment is renowned as the most environmentally friendly process of dimensional stabilization that can be applied to wood, in order to make it suitable for outdoor uses. It also darkens wood color and improves wood durability. The intensity of heat treatment can be appreciated by means of two parameters: the color change occured in wood due to the high temperature, and the mass loss, which is a measure of the degree of thermal degradation. In order to find a mathematical correlation between these two parameters, an experimental study was conducted with four European wood species, which were heat-treated at 180°C and 200ºC, for 1-3 hours, under atmosheric pressure.The paper presents the results concerning the color changes and mass losses recorded for the heat-treated wood samples compared to untreated wood.  For all four species, the dependency between the color change and the mass loss was found to be best described by a logarithmic regression equation with R2 of 0.93 to 0.99 for the soft species (spruce, pine and lime), and R2 of 0.77 for beech. The results of this study envisage to simplify the assessment procedure of the heat treatment efficiency, by only measuring the color – a feature that is both convenient and cost-effective. 


Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1275 ◽  
Author(s):  
Yanjie Mou ◽  
Zhichao Li ◽  
Xiaoteng Zhang ◽  
Devesh Misra ◽  
Lianfang He ◽  
...  

High strength/high elongation continues to be the primary challenge and focus for medium-Mn steels. It is elucidated herein via critical experimental analysis that the cumulative contribution of transformation-induced plasticity (TRIP) and microstructural constituents governs high strength/high elongation in 0.2C–3Al–(6–8.5)Mn–Fe steels. This was enabled by an effective heat treatment involving a combination of intercritical hardening and tempering to obtain high strength/high ductility. An excellent combination of high ultimate tensile strength of 935–1112 MPa and total elongation of 35–40% was obtained when the steels were subjected to intercritical hardening in the temperature range of 700–750 °C and low tempering at 200 °C. The intercritical hardening impacted the coexistence of austenite, ferrite, and martensite, such that the deformation behavior varied with the Mn content. The excellent obtained properties of the steels are attributed to the cumulative contribution of the enhanced TRIP effect of austenite and the microstructural constituents, ferrite and martensite. The discontinuous TRIP effect during deformation involved stress relaxation, which was responsible for the high ductility. Lamellar austenite, unlike the equiaxed microstructure, is envisaged to induce stress relaxation during martensitic transformation, resulting in the discontinuous TRIP effect.


2018 ◽  
Vol 347 ◽  
pp. 54-65 ◽  
Author(s):  
Guo-Hui Meng ◽  
Bang-Yan Zhang ◽  
Hong Liu ◽  
Guan-Jun Yang ◽  
Tong Xu ◽  
...  

2021 ◽  
Author(s):  
James Jan ◽  
Steve Swisher ◽  
Mohammed Yusuf Ali ◽  
Shanmugasundaram Chandrakesan

Abstract Engine cylinder block cracking is a costly engine component failure that is often discovered late, either in the product verification phase by dynamometer testing or after product launch during vehicle operations. It is well established that the crack issues are related to the residual stress induced in the casting and heat treatment processes. To identify the quality risk in a short turn-around time and a cost-effective fashion, using computer simulations to evaluate the state of stress during casting and heat treat processes is the trend in automotive industry. In recent years, CAE methodologies have advanced significantly in both CFD and FEA to model the casting process, the quenching process, the residual stress, and the high cycle fatigue (HCF). However, calculating the final stress in the cylinder block requires several CAE software tools to work together as an integrated, streamlined engineering method and these CAE tools could be very different in meshing topologies, numerical methods, data structure, and post-processing capabilities. The intent of this research is to develop an integrated virtual engineering methodology combining casting simulation, computational fluid dynamics and finite element method to simulate the manufacturing process from the beginning of casting, through water quenching heat treatment, to engine dynamometer testing. The methodology involves three CAE tools, MAGMASOFT®, AVL FIRETM/FIRETM-M and ABAQUS, and considerable amounts of research and development work are concentrated on the validation of each individual numerical method and tools for data exchange between the software tools.


2003 ◽  
Vol 125 (2) ◽  
pp. 188-194 ◽  
Author(s):  
Andrew M. Freborg ◽  
B. Lynn Ferguson ◽  
Michael A. Aronov ◽  
Nikolai I. Kobasko ◽  
Joseph A. Powell

An alternative method for the hardening of steel parts has been developed as a means of providing steel products with superior mechanical properties through development of high residual compressive stresses on the part surface, and involves the application of intensive quenching during heat treatment. This processing method, termed “Intensive Quenching,” imparts high residual compressive stresses on the steel surface, thus allowing for the use of lower alloy steels, reduction or elimination of the need for carburization and shot peening, and providing for more cost-effective heat treating. Intensive quenching also provides additional environmental benefits, as the process uses plain water as the quenching media in contrast to traditional heat treatment practices which typically employ hazardous and environmentally unfriendly quenching oil. This paper presents an overview of the theory and application of intensive quenching, as well as provides experimental and computational data obtained for a variety of steel products. Also presented will be results of computer simulations of temperature, structural and stress/strain conditions for a typical pressure vessel during intensive quenching.


Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 961 ◽  
Author(s):  
Stefania Toschi

The aim of the present work is the study of T6 heat treatment of A354 (Al-Si-Cu-Mg) casting alloy. The heat treatment was optimized by maximizing mechanical strength of the alloy while keeping the treatment cost effective, reducing treatment time and temperature. Due to the presence of low melting compounds, a double stage solution treatment was proposed. The first stage was aimed at the homogenization and dissolution of the low melting phase while a second stage at a higher temperature was evaluated to foster dissolution of Cu/Mg rich intermetallics and keep the solution time and temperature as low as possible. Microstructural investigations were performed through optical and electronic microscopy, which allowed the assessment of the evolution of intermetallic phases during the solution treatment. Artificial aging was studied at different temperatures from 160 °C to 210 °C where the peak aging condition was identified. Over aging of the heat treated alloy was evaluated by soaking T6 samples at 200, 245, and 290 °C for up to 168 h. Tensile behavior of the T6 and over-aged alloy (i.e., after soaking at 210 °C for 50 h) was evaluated at room temperature. Results showed that the proposed treatment allowed the enhancement of mechanical properties of the alloy in comparison to industrial practice treatment, maintaining a good level of ductility and conferring a superior resistance to long-term high temperature exposure.


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