Development of Pb-Free Austenitic Stainless Steels

2013 ◽  
Vol 791-793 ◽  
pp. 486-489
Author(s):  
Zhuang Li ◽  
Di Wu ◽  
Wei Lv

Pb-free austenitic stainless steels were investigated by adding sulfur, rare earth (Re) elements and bismuth. The metallurgical properties, machinability and mechanical properties of both steels were examined. The results show that a significant amount of grey, spindle shaped inclusions were discovered in austenitic stainless steels, and they should belong to MnS inclusions containing bismuth element and rare earths oxide. The addition of S, Bi and Re to austenitic stainless steels improved the machinability. The machinability of steel B is better than that of steel A in a way. The mechanical properties of steel B are better than those of steel A, especially total elongation owing to the presence of rare earth elements. From the viewpoint of life cycle assessment, it is proposed that the development of Pb-free austenitic stainless steels containing S, Bi and Re is desirable.

2013 ◽  
Vol 377 ◽  
pp. 128-132
Author(s):  
Zhuang Li ◽  
Di Wu ◽  
Wei Lv ◽  
Shao Pu Kang ◽  
Zhen Zheng

Rare earth elements (REE) are harmless for human health. REE addition contributes to the improvement of the machinability of the steels. In the present paper, machining characteristics of austenitic stainless steels without lead addition were investigated by adding free-machining elements, such as sulfur, REE and bismuth. The results have shown that large numbers of rounded, globular shaped inclusions were obtained for both steels. The machinability of steel B is better than that of steel A, and the cutting forces of steel B are lower than those of steel A at various cutting speeds. Lead can be substituted by REE and bismuth in free machinable austenitic stainless steels. REE significantly affects machining characteristics of austenitic stainless steels without lead addition. The mechanical properties of both steels were similar, and their fracture exhibited ductile characteristics. Satisfactory machinability and mechanical properties can be obtained for both steels.


2013 ◽  
Vol 377 ◽  
pp. 112-116 ◽  
Author(s):  
Zhuang Li ◽  
Di Wu ◽  
Wei Lv ◽  
Zhen Zheng ◽  
Shao Pu Kang

In the present paper, sulfur, RE (rare earth) and bismuth were added to an austenite stainless steel. Low environmental impact machining processes of free cutting austenitic stainless steels was investigated by machinability testing. The results show that a significant amount of grey and dispersed inclusions were found in steel B. The inclusions are typical sulfide inclusions, and bismuth element is attached to double end of manganese sulfide inclusions. Some inclusions exhibit globular shape due to the presence of rare earths elements in steel B. Chip morphology was improved in steel B under the same turning conditions. The machinability of steel B is much better than that of steel A. This is attributed to the presence of free-cutting additives of sulfur, RE and bismuth in the austenitic stainless steels. Satisfactory mechanical properties were also obtained under the conditions of our experiments. The reasons why satisfactory mechanical properties were obtained may lie in that the sulfides and bismuth are soft phase, and the presence of rare earths elements contributes to the improvement of the toughness of the austenitic stainless steels.


2012 ◽  
Vol 430-432 ◽  
pp. 306-309 ◽  
Author(s):  
Di Wu ◽  
Zhuang Li

In this paper, a new non-lead machinable austenitic stainless steel was investigated. The metallurgical properties, machinability and mechanical properties of the developed alloy were compared with those of the conventional austenitic stainless steel 321. The results have shown that the presence of machinable additives, such as sulfur, copper and bismuth, etc. contributes to the improvement of the machinability of austenitic stainless steel, because the inclusions are something like internal notches causing crack nucleation and facilitating rupture. Bismuth has a distinct advantage over lead. The machinability of the austenitic stainless steels with free-cutting additives is much better than that of austenitic stainless steel 321. The mechanical properties of the free cutting austenitic stainless steel are similar to those of 321 although the former are slightly lower than those of the latter.


Alloy Digest ◽  
1999 ◽  
Vol 48 (8) ◽  

Abstract ALZ 316 is an austenitic stainless steel with good formability, corrosion resistance, toughness, and mechanical properties. It is the basic grade of the stainless steels, containing 2 to 3% molybdenum. After the 304 series, the molybdenum-containing stainless steels are the most widely used austenitic stainless steels. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, and joining. Filing Code: SS-756. Producer or source: ALZ nv.


Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2622
Author(s):  
Malcolm Griffiths

Austenitic stainless steels are used for core internal structures in sodium-cooled fast reactors (SFRs) and light-water reactors (LWRs) because of their high strength and retained toughness after irradiation (up to 80 dpa in LWRs), unlike ferritic steels that are embrittled at low doses (<1 dpa). For fast reactors, operating temperatures vary from 400 to 550 °C for the internal structures and up to 650 °C for the fuel cladding. The internal structures of the LWRs operate at temperatures between approximately 270 and 320 °C although some parts can be hotter (more than 400 °C) because of localised nuclear heating. The ongoing operability relies on being able to understand and predict how the mechanical properties and dimensional stability change over extended periods of operation. Test reactor irradiations and power reactor operating experience over more than 50 years has resulted in the accumulation of a large amount of data from which one can assess the effects of irradiation on the properties of austenitic stainless steels. The effect of irradiation on the intrinsic mechanical properties (strength, ductility, toughness, etc.) and dimensional stability derived from in- and out-reactor (post-irradiation) measurements and tests will be described and discussed. The main observations will be assessed using radiation damage and gas production models. Rate theory models will be used to show how the microstructural changes during irradiation affect mechanical properties and dimensional stability.


2012 ◽  
Vol 736 ◽  
pp. 307-315 ◽  
Author(s):  
Murugavel Suresh ◽  
Satyam Suwas

Mg alloys show limited room temperature formability compared to its lightweight counterpart aluminium alloys, which is a main obstacle in using this metal for most of the structural applications. However, it is known that grain refinement and texture control are the two possibilities for the improvement of formability of magnesium alloys. Amongst the approaches attempted for the texture weakening, additions through of rare-earth (RE) elements have been found most effective. The relationship between the texture and ductility is well established. In this paper, the effect of rare earth addition on texture weakening has been summarized for various magnesium alloys under the two most common modes of deformation methods.


2021 ◽  
Author(s):  
Ivan L. Pinto

The objective of this project was to provide an overview of Life Cycle Assessment (LCA) and to demonstrate its application as a tool to provide a scientific comparison of alternative construction options for a commercial building in the Canadian context. The work entailed a quantitative assessment of the embodied environmental impacts of typical office buildings using a steel frame, and a concrete frame alternative (and associated components) in Toronto. Through the use of four assessment strategies, this study has indicated that the steel framed building performs better than the concrete building in most impact indicators, excepting primary energy and eutrophication potential. However, additional buildings should be assessed in order to confirm this finding. Furthermore, it was found that the manufacturing phase represents over 90% of the embodied impacts of the whole building. The study also advises caution when comparing different LCA studies and identifies its difficulties.


2017 ◽  
Vol 23 (2) ◽  
pp. 111 ◽  
Author(s):  
Andrea Di Schino ◽  
Maria Richetta

<p>Even if relations predicting the mechanical properties on bars of austenitic stainless steels are already available, but no systematic works was carried out in order to predict mechanical properties in after cold rolling and annealing.   The tensile properties of a large number of cold rolled and annealed AISI 304 stainless steel are here correlated with their chemical composition and microstructure. Quantitative effects of various strengthening mechanisms such as grain size, d– ferrite content and solid solution strengthening by both interstitial and substitutional solutes are described. Interstitial solutes have by far the greatest strengthening effect and, among the substitutional solutes, the ferrite – stabilising elements have a greater effect than the austenite – stabilising elements. Regression equations are developed which predict with good accuracy the proof stress and tensile strength in AISI 304 stainless steels.</p>


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