IFHTSE Global 21: heat treatment and surface engineering in the first decades of the twenty-first century: Part 1 – Introduction to ongoing IFHTSE activity

Abstract

Engineering systems and components are the result of a complex chain of actions, starting with a design to match the functional demands: materials science and technology are intimately involved; there are often multiple stages in the manufacturing process, as well as essential quality assurance methods for the component and system. Each step in the process has significance; optimum outcomes and cost effectiveness depend heavily on their being orchestrated and managed as an integrated sequence. Depending on the circumstances, the relative importance of each step may be viewed differently, but the heat treatment and surface engineering manufacturing processes are always likely to be critical. These processes themselves represent a complex balance of materials, technology, energy and environmental factors to achieve an optimum combination of functionality, industrial feasibility and economic and social viability.     

IFHTSE Global 21: heat treatment and surface engineering in the first decades of the twenty-first century Part 12 – A synthetic update

Abstract

A synthesis report is presented on progress to end 2009 in the IFHTSE initiative Global 21: heat treatment and surface engineering in the first decades of the twenty-first century. Launched in 2005, Global 21 was set up as a framework within which to conduct an evolving study on the state of the art and development trends in heat treatment and surface engineering. Its objectives were, and remain: to outline current economic, political, scientific, and industrial factors globally and set heat treatment and surface engineering against that background; to generate specific papers and other contributions on a range of economic, scientific and industrial topics from recognised authorities; and to hold workshops and discussions whenever possible or appropriate at IFHTSE conferences.     

IFHTSE Global 21: Heat treatment and surface engineering in the twenty-first century Part 8 – Training in heat treatment and surface engineering

Abstract

It is well known that metallurgists, materials scientists and engineers all have some training in heat treatment and surface engineering (thermal processing) as an intrinsic part of their courses, irrespective of the qualification to which the course leads. However, for those who are going to work in the thermal processing industry or have responsibility for that area of their business, it has to be acknowledged that the level of training is not in sufficient depth to allow them to conduct the business in the best possible manner. In other words, additional training is required. How employees were trained some years ago is compared with the training that is available today, and measures to ensure that sufficient appropriately trained people are available to the industry in the future are proposed. Although the main thrust of this paper will be applicable to all businesses carrying out thermal processing, it is very much based on the author's experience of working for Bodycote, a major thermal processing service provider, for the past 31 years. My many discussions in both Europe and the USA with both colleagues and educators have led me to believe that the UK experience is far from unique.     

IFHTSE global 21: heat treatment and surface engineering in first decades of twenty-first century Part 5 – Modelling based design of surface engineered systems

Abstract

Aspects of surface engineering design, namely, simulation of processing and service behaviour and prediction of properties, are discussed and summarised. Available design techniques are demonstrated by means of examples. Two process simulation modelling approaches, relating to oxidation of Ti alloys and nitriding of steels, are described. A novel optimisation approach to extract Young's modulus, yield strength and work hardening exponent of a power law (load–displacement) material is presented. Design and service behaviour simulation case studies of surface engineered titanium alloy gears for the sports car industry are also presented. It is shown that advances in theoretical principles and computational methodologies and tools, together with the ever increasing abundance and accuracy of thermodynamics and kinetics databases of materials and processing atmospheres, have enhanced the reliability of surface engineering simulations to a level good enough for industrial application. Barriers and development trends in surface engineering design are also addressed.     

IFHTSE Global 21: heat treatment and surface engineering in the first decades of the twenty-first century: Part 2 – Heat treatment in China: present and future

Abstract

The large state-owned enterprises in China have achieved great progress in heat treatment production technologies over the last 10 years. In addition, the number of smaller commercial heat treatment plants has increased rapidly to more than 3000. Heat treatment plant and equipment manufacturing flourishes. However, because China covers a vast territory with uneven regional development, and consequently little uniformity across the individual enterprises, there are still obvious gaps compared with the advanced level globally. Therefore the 11th Five-Year Plan for the heat treatment industry, formulated by the China Heat Treatment Association (CHTA) and the Chinese Heat Treatment Society (CHTS) prioritises equipment renovation as the way ahead for production technology innovation. Based on a nation-wide survey, the 11th Five-Year Plan described the current status, identified the shortcomings, formulated the guiding principles and directions for development, and put defined key R&D initiatives and other measures for achieving progress. A vision up to 2020 was set out.     

IFHTSE Global 21: heat treatment and surface engineering in the twenty-first century: Part 9 – Influence of materials science on heat treatment and surface engineering

Abstract

Significant progresses have been made in the past decades in the discipline of materials science, which include, but not limit to, the synthesis of new materials, advancement in analytical and experimental techniques, sustainable and environmentally friendly processing technologies, computational material science and nanotechnology. These developments have major influences on the research and application of heat treatment and surface engineering, and provide new opportunities to engineer the surfaces of new and conventional materials using advanced technologies to meet the ever increasing demands in surface and subsurface related properties. This survey gives a brief review on some aspects of heat treatment and surface engineering which keep pace with new developments in materials science. The specific areas being examined include: (i) advanced analytical techniques; (ii) sustainable and environmentally friendly technologies; (iii) surface engineering of emerging new materials such as intermetallic compounds, shape memory alloys and biomaterials; (iv) the search for superhard coatings and surface nanostructured materials; (v) mathematical modelling of surface engineering systems.     

IFHTSE Global 21: heat treatment and surface engineering in the twenty-first century: Part 11 – Survey of the heat treatment and surface engineering industry in Argentina at the beginning of the twenty-first century

Abstract

Heat treatment and surface engineering are enabling technologies for modern industry in technologically developed countries. However, the technical requirements of industry in the developing countries, and particularly in Argentina, are often not so demanding. This article is an attempt to reflect the current status of heat treatment and surface engineering in Argentina at the beginning of the twenty-first century, particularly in terms of available technology and human resources. Emphasis is also given to the future prospects of this area of engineering.     

IFHTSE Global 21: heat treatment and surface engineering in the twenty-first century Part 15 – Progress in surface heat treatment using electron beam surface hardening

Abstract

By using high frequency beam deflection techniques it is possible to carry out highly productive electron beam (EB) surface treatment. As a result of comprehensive investigations about the influence of EB parameters on structure and properties of the material in connection with EB hardening of steels and cast irons over the last 25 years, very interesting industrial applications are available now. The paper deals with the state of the art in this field.     

IFHTSE Global 21: heat treatment and surface engineering in twenty-first century Part 17 – Heat treatment and surface engineering in the metals industry in Thailand

Abstract

Manufacturing and the metallurgical industries in Thailand have developed rapidly over the past 30–40 years. For example, the Thai automotive industry has a production capacity of two million vehicles and is now the thirteenth largest in the world. Nearly all large manufacturing plants in the auto- and electronics sectors are joint ventures with multinational companies; the levels of equipment, tooling and technology in these plants, established on purpose built industrial estates, are world class. However, the engineering and parts manufacturing sector in general consists mainly of smaller companies which cannot afford the same levels of investment. In striving to meet increasing competition, these smaller companies encounter problems in productivity, quality, cost reduction, energy efficiency and environmental performance. Against this background the status and future development of heat treatment and surface engineering (HTSE) processes across manufacturing industry in Thailand is reviewed. The increased contributions to improvements in HTSE practice and understanding required from education and training, R&D and technical bodies such as The National Metal and Materials Technology Centre and IFHTSE are considered. It is concluded that, as for other Thai industrial sectors, there should be a ‘master plan’ for HTSE in Thailand.     

IFHTSE Global 21: heat treatment and surface engineering in the twenty-first century Part 13 – Advances in tool steels and their heat treatment: Part 1 – Cold work tool steels

Abstract

Several new tool steel grades as well as optimised modifications of standard grades have been developed by special steel producers during the last one to two decades. These steels offer the potential for better properties and tool performance, but only if the heat treatment is performed with an optimum combination of parameters. The achievement of this potential is supported by advanced heat treatment equipment and processes. This paper gives an overview of the possibilities, requirements and optimum heat treatment parameters of these new tool steels based on the examples of cold work tool steels. Thereby special attention is paid to 8%Cr steels, spray formed steels, powder metallurgy steels as well as surface hardening and cryogenic treatment. A second part will be published successively, with examples on hot work tool steels and tool steels for plastic moulding.     

IFHTSE Global 21: heat treatment and surface engineering in the twenty-first century Part 19 – Type I quenchants for quenching of aluminium: a review

Abstract

Some aluminium forgings and castings are cold water quenched in order to achieve the desired design minimum physical properties. When unacceptable distortion or cracking is encountered, hot water has traditionally been specified as an alternative quenchant. However, hot water quenching typically results in a significant loss of mechanical properties and a significant increase in the potential for intergranular corrosion. Approximately 30 years ago, SAE designated Type I poly(alkyleneglycol) copolymer quenchants were introduced as an alternative to hot water. These quenchants offered significant, often dramatic, advantages in residual stress and distortion reduction while still achieving the Mil-Handbook 5 design minimum properties. However, even though these quenchants have been available for such a long time, there is still wide spread misunderstanding regarding how they work, when they should be used and how they should be monitored. The objective of this paper is to address these issues.     

IFHTSE Global 21: heat treatment and surface engineering in the twenty-first century Part 7 – Thermal processing and past,present and future development of automotive sheet steels

Abstract

The alloying, thermal processing, microstructure and properties that have resulted in a remarkable number of new automotive sheet steels developed and applied over the past several decades are surveyed. The powerful forces that have driven the development of new sheet steels, and the coupling of mechanical design, professional society promotion and international technical conferences that have established an extensive knowledge base for present and future developments, are reviewed. Sheet steels, because of differences in chemistries, processing and mechanical requirements from those applied to bar, forged and tool steels, are not typically considered in IFHTSE programming, but the factors that have led to the dynamic changes in automotive sheet steels, and the resulting knowledge base related to heat treatment and thermal processing, deserve to be considered in the context of Global 21.     

Influence of short-term heat treatment on the microstructure and mechanical properties of EN AW-6060 T4 extrusion profiles—Part B

In the automotive industry aluminium and its corresponding semi-finished products contribute an essential part to the aim of weight reduction in car body structures. Aluminium alloys of the 6000 series with Mg and Si contents are preferred because of the possibility to increase strength by ageing processes. However, the cold formability in comparison to other materials like mild steels is quite low and due to this, complex parts are only producible at higher temperatures. Therefore, the so called Tailor Heat Treatment was developed to improve the cold formability of aluminium alloys. In this approach, a short-term heat treatment is conducted to achieve a local softening of the material due to dissolution of Mg and Si clusters (retrogression). This effect is used to improve the material flow, relief critical forming zones and enhance the overall formability of the material. Afterwards, strength can be increased again by ageing processes. However, up till now a holistic process understanding, taking into account all process parameters as well as a microstructural explanation is missing. Therefore, the focus of the fundamental investigations lies on connections between the mechanical properties and short-term heat treatment with industry-relevant heating rates as well as natural and artificial ageing process. Conclusively, the evolution of the mechanical properties with regard to the natural ageing process is compared with findings of DSC analysis, which were discussed in Part A. Based on these results, a process window is derived for the subsequent forming process and the final mechanical properties of the final part in dependency of the forming history as well as the artificial ageing process, are identified.     

Study of the transient processes and the effect of the electrode’s surface structure on the heat transfer in a wire EHD heat exchanger

The results of the experimental investigation of an EHD plated heat exchanger are presented. The electrode system consists of two sections of staggered thin wires to which an alternative potential high voltage is applied with the thermostatted plate being neutral. PMS-50 was the working liquid. We calculated the coefficient of the enhancement by the electric field on the basis of the experimental data.     

Effect of heat treatment of the mechanical properties and corrosion resistance of welded joints in high-strength aluminium–lithium alloys

Experimental results show that the maximum level of strength characteristics is obtained in complete heat treatment (quenching + artificial ageing) after welding. The heat treatment of friction stir welded joints results in the equalization of the structural heterogeneity and removal of softening in the heat-affected zone. Post-weld heat treatment conditions have almost no effect on the protective properties of non-metallic inorganic coatings. The susceptibility to intercrystalline corrosion (ICC) of welded joints with anodic oxide and chemical oxide coatings is also eliminated.     

Preconditioning of AISI 304 stainless steel surfaces in the presence of flavins—Part I: Effect on surface chemistry and corrosion behavior

Stainless steel AISI 304 surfaces were studied after a mild anodic polarization for oxide growth in the presence and absence of two derivatives of vitamin B2 (riboflavin and flavin mononucleotide) that can be secreted by metal-reducing bacteria and act as a chelating agent for iron species. The alterations in oxide chemistry were studied by means of surface-sensitive techniques such as X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry analysis. The complementary electrochemical characterization revealed a preferential growth of an oxide/hydroxide iron-rich film that is responsible for an altered pit initiation and nucleation behavior. These findings suggest that as the corrosion behavior is determined by the interplay of the chemical and electronic properties, only a mild anodic polarization in the presence of redox-active molecules is able to alter the chemical and electronic structure of the passive film formed on stainless steel AISI 304. This helps to achieve a profound understanding of the mechanisms of microbially influenced corrosion (MIC) and especially the possible effects of the redox-active biomolecules, as they may play an important role in the corrosion susceptibility of stainless steel surfaces.     

Microanalytical study of discontinuous precipitation and dissolution in Ni–4 at.% Sn: local and global characterization of the reactions

The morphology and kinetics of the discontinuous precipitation (DP) and discontinuous dissolution (DD) reactions have been studied in a Ni–4 at.% Sn alloy. High spatial resolution energy-dispersive X-ray microanalysis has been used to determine the Sn concentration profiles left behind the moving reaction front for the individual cells of the Sn-depleted α lamellae and Ni₃Sn compound. These data, combined with the local values of the reaction front velocity and the thickness of the α lamellae, have been used to evaluate the local sδD_b values (D_b is the grain-boundary chemical diffusion coefficient, δ is the grain-boundary thickness and s is the segregation factor). The obtained results have been compared with those calculated by the global approach to the DP and DD reactions, which is relevant for the whole population of the cells. It has been shown that the application of the local characterization of the DP and DD reactions removes essentially the differences between the sδD_b values calculated by the Petermann–Hornbogen equation and the equations of Cahn and Zięba–Pawłowski. Moreover, both sets of data do not show any substantial differences from the sδD_b values obtained from measurements of the tracer diffusion of tin along stationary grain boundaries in nickel.     

Influence of heat input and post-weld heat treatment on boiler steel P91 (9Cr–1Mo–V–Nb) weld joints Part 1 – Microstructure

Abstract

Steel P91 is known for its excellent high temperature properties. The achievement of optimum weld metal properties for steel P91 within the course of its extensive applications in power plants has however often caused concern. In the present work, three thick pipes of P91 steel were welded using three different levels of heat inputs within the range of 1·15–3·5 kJ mm^?1. A circumferentially multipass butt welded P91 steel pipe, typically used for high temperature applications in power plants was selected for this investigation. The achievements of optimum weld metal properties, which are closely linked to microstructure, are known to cause concern in such weldments. Two types of heat treatments were employed, subcritical post-weld heat treatment and normalising/tempering treatment. The microstructure was evaluated by optical, scanning electron microscope, X-ray diffraction and magnetic permeability. The results have shown a great influence of heat input and heat treatment on the microstructure. Martensite and ferrite were the main structures obtained. Bainite and δ-ferrite have been observed in the weld metal, heat affected zone and weld metal for all heat input/treatment conditions. The volume fraction of bainite and δ-ferrite increased with increase in heat input till a critical value slightly lower than 1·15 kJ mm^?1; then decreased with the increase in heat input. The normalising/tempering treatment resulted in a decrease in the volume fraction of δ-ferrite and bainite compared to the subcritical post-weld treatment which is conventionally used. This explains the enhancement in the toughness and creep properties of the steel presented in the second paper.