Question

Prablems 0-/0.18 te ster ATdiagram on Ay on next page on a Lor scale 0,45 phase diagrem At wto C 0,77, yar proevlechrid product will be (known as ferrile and denoted with in Chap 0). At wt.?0 C0.7, your proestectoid product will be c lalso known as arbide or cenentik and denoted as At t o, the t curres on the diagram should extrapolafe ut to points oa h phase digian that corrtspond to the perahue ranges forthe proetechd evtkcfoid ra reachdns Capctad Cin Chap. 1). lut.c 13 rite Temperature, °C Fe-C Equilibrium Phase Diagram 1600 Wicci- 1400 1200 Ausleauke Tiquid extechic 1000 008 a* 7 can parbide Ferilesoo eutech .ORE Fezc garbide jes p:smosnii Wth c pearlile dehnes How because verfical Weight percent oarban ghase |ndary http://www.public.asu.edu/^jbadams/PhaseDiaIV.sca.hqx Can be dssolrelin impurty limit 2 O.2wt%C Florida Iustitute of Technology CHE 3260 Chaplet 10 Phase Trunsfarmations in Motals 824 of a small specimen that has been sabjected to the lollowing time-temperatoro treat ments. In ench case assumo that the spec men begins at 845 C (1550F), and that it has been beld at this temperatuielong enough to have achieved a complete and homogeneous austenitic structure. 1013 What is the driving forco for the focnation of spheroidite? 1034 Using the isothermal bansformation dia- gram for an iron-carbog alloy of eutectoid composition (Figre 10,14), specify the na ture of the fimal microstructure (in terms of microconstitnents present and approximate. parcentages of cach) ofa small apecimen that has been nbjected to the folowing time- temperatire treatments.In each case assume that the specimen begins at 760 C (1400F) and that it has been held at this temperature long enough to have achieved a complete and homogeneOus austenitic strnoture. (a) Cool rapidly to 700 C (1290 F), hold for 10 s, then quench to room temperature. (a) Rapidly cool to 250 C (480F), hoid for 10 s, then quench to room temperature (b) Rapidly cool to 700°C (1290F), hold for 30 s, then quench to room temperature. (e Rapidly cool to 400C (750E), hold fr S00, then quench to room () Rapidly cool to 700C (1290F), hold at this temperatre for 10, then quench to on temperature. (e) Rapidly cool to 650C (1200F, bold et this teuperatire for 3s, rapidly cool to 400C (750"F, hold for 10 , then qench to room temperature Rapidly cooi lo 450 C (840"F, hold for 10 s, then quench to room temperatore. (eRapidly cool to 625 C (1155F), hold for 1s, theu quench to room temperature. Ch) Rapidly cool to 625C (1155 F), hold at this temperature for 10 s, Tapidly cool to 400 C (750F), hold at this temperature for 5s, then quench to room temperature temperature. (b) Rehbat the specimen in part a to 700 C (1290F) for 20 h (e Rapidly cool to 600C (1110F), hold for 4s, rapidly cool to 450°C (840F), hold for 10, then quench to room temperatore. (d) Cool rapidly to 400C (750F), hold for 2s, then quench to room temperature. (e) Cool rapidly to 400°C (750F, hold for 20 s, then quench to toom tempersture, S. Cool rapidly to 400C (750F), hold for 200, then quench to room temperature Rapidly cool to 575°C (1065"F), bold for 20s, capidly cool to 350°C (660F), hold for 100 , then qaench to room temperatore. (h) Rapidly cool to 250 C (480F), hold for 100s, then quench to room temperature in water. Raheat to 315 C (600 F) for 1 h and slowly cool to room temperature. 10.17 Far parts a, c, d, f, and h of Problem 1016, dotermine the approximate percentages of the microconstituents that form. 10.18 Make a copy of the isothermal transforma ion diagram for a 0.45 wt% Ciron-carboa alloy (Figure 1029), and then sketch and label on this diagram the time-tempatature paths to prodnce thb following microstrue 10.15 Maka a copy of the isotbermal transforma- tion diagram for an iron-carbon alloy of eu- tectoid composition (Figure 10.14) and then sketch and label on this diagram timo- temperature paths to produce the following microstructares tures (a) 42% proeutectoid fesrite and 58% peadite (b) S0% fine pearlite and S0% bainite. (e) 100% martensits. (d) 50% martensite and S0 % austenita coarse (a) 100% coase pearlite. (b) 100% tempered martensite. (c) S0% coarse pearlite, 25 % bainite, and 25% martensite. 10.19 Name the microstructural products of euteo toid iron-carbon alloy (0.76 wt% C) speci- mens that are Brst completely transformed to austenite, then cooled to room tempera ture at the following rates: (a) 200Cs. (b) 100Cs, and (e) 20°C/s 10.16 sing the isothemal transformation dia gan for a 045 wt C steel alloy (Figure 10.29), determine the inalmicrostrnctire (in terms of jnst the microconsdtoents present) 5% 4 Temperature (C) ENCHE 10.2 Isother mal transformation dia- gram for a 0,45 wt% C iron-carbon alloy: A austenite; B, bainite; F proeutectoid ferrite; M, martensite; P, pearlite. Adapted from Atlas of Fime-Temperature Dia 006 008 00 A+ F grams for Irons and Steels, G. F. Vander Voort, Editor, 1991. Re- 009 www printed by permission of ASM International, 91 Materials Park, OH.) 009 004 M (start) A+ B 008 MYO0%) (%09) %0g 000 00t 08 martensile 09 OI (s) eu

Answer 1

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