Grey iron is usually quenched and tempered to increase its resistance to wear and abrasion by increasing hardness with a structure consisting of graphite embedded in hard martensite. White cast irons are hard, brittle, and unmachinable, while gray irons with softer graphite are reasonably strong and machinable. The increase in strength and toughness can be obtained by making the flakes finer such as in meehanite iron and by reducing the total volume of graphite by having less contents of carbon and silicon. Chemical composition (mass.%) of Fe–C–Cr–V white irons Alloy Element C P S Si Mn Mo Cu Ni Cr V 1 2.89 0.025 0.061 0.85 0.71 0.48 0.99 0.100 19.03 0.0012 Ashby, Michael; Hugh Shercliff; David Cebon (2007). High chromium (25% Cr and 28% Cr) white irons have the best combination of excellent abrasion resistance and toughness (to bear the repeated heavy impact loading), because these have hard but discon­tinuous M 7 C 3 eutectic carbides (low Cr-alloys have relatively softer and continuous M 3 C eutectic carbides). ISBN 978-0-691-07097-1. 15.14. Cast irons are iron-carbon (and silicon) alloys having carbon or carbon equivalent value, more than 2% (actually it is 2.1 1%), i.e., more than the maximum solid solubility of carbon in austenite such that the eutectic reaction occurs during solidification. Once the graphite flake has formed, its shape cannot be changed later by any method. ISBN 978-0-7506-8391-3. The unalloyed cast irons have silicon and manganese. 15.2 illustrates the effect of section size, (i.e., the rate of cooling) and the carbon equivalent value on the type of structure, and thus, the type of cast iron obtained. For high strengths, carbon is kept on lower side (to have low volume of graphite) and silicon on higher side (keeping a balance to get good machinability). Copyright 2020 Nuclear Power for Everybody | All Rights Reserved | Powered by, Interaction of Beta Radiation with Matter, Interaction of Gamma Radiation with Matter, Grossi highlights IAEA's activities for UN General Assembly, US Senate committee includes uranium reserve in FY2021 allocations, CGN's Hualong One design certified for European use. J. R. Lamarsh, A. J. Baratta, Introduction to Nuclear Engineering, 3d ed., Prentice-Hall, 2001, ISBN: 0-201-82498-1. !9�Q�������Ţ�J���0��3<9C7��A�8 ��}�8�6b= ��4���N�ż��/~�z{�)niC��N��d?���ǝ�l�_���f���!� 9�f!9�Ͼ����c��N��.C}s���,�ơ��)�y2�!�7��89����p6�'Y��uQ6̪@�/���?V�1��>/'���w;� ��׏���p�Wu���7)�çd��XLÌ"�wwI�eq<8�rQrx���]w"�(Ç뚼�Z� �����HڑU�X:5��oo�9�I�`C�Raj��o� v�r�w��O&yrY|�� As the higher carbon contents make them more brittle, industrial cast irons have carbon normally in the range of 2.11 to 4% and silicon 0.5 to 3% (along-with … Gaskell, David R. (1995). 1) You may use almost everything for non-commercial and educational use. 2) You may not distribute or commercially exploit the content, especially on another website. Manganese, thus, has indirect effect to promote graphitisation as it removes sulphur, (which promotes cementite formation). Our Website follows all legal requirements to protect your privacy. Disclaimer 8. Image Guidelines 4. H��T]k�0�+�Q�Z�d[�aֲ� �0�n���&*���NC���d{q>�p�?ttι�����[�.�� ��S��R�__�2fI��j�5��l`N)"b���7�#z�� ��Ä*U,�,�L��kC� u0>�:f*�L�L�f���?��+3�����p�KJEͣ�~�30�`JQ-W�5!5�$ٸ�fOY������r�&�ꬽBe,=a]�(#����(��5��-�V���_��@�/s0�SL)Nu. Princeton University Press. Why Things Break: Understanding the World by the Way It Comes Apart. Thus, S.G. irons have higher strengths in tension and bending along with ductility. The structure of white cast iron consists of pearlite and ledeburite, a eutectic mixture of pearlite (converted from austenite) and cementite. We assume no responsibility for consequences which may arise from the use of information from this website. Heating the graphitic iron can modify its matrix. Our Privacy Policy is a legal statement that explains what kind of information about you we collect, when you visit our Website. 15.2 shows that pearlitic grey iron of CEV = 4.2, should be of size between 15 mm to 4.5 mm thick plate, or 30 mm to 8.5 mm dia. Carbon is present in the following two forms: 1. and are expensive, but result in much higher strength, ductility and toughness. Silicon also lowers eutectoid carbon content. When it is being heated, then at temperatures approa­ching the lower critical temperature, above about 540°C, its silicon can cause the cementite of pearlite to dissociate into ferrite and carbon.

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