[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"detail-sidebar-cat-0-en-105":3,"doc-seo-657734-105":59,"doc-detail-657734-en":130},{"code":4,"msg":5,"data":6},0,"success",[7,13,18,23,28,33,38,43,48,51,55],{"id":8,"doc_module":4,"doc_module_name":9,"category_name":10,"show_sort_weight":11,"slug":12},1,"Document","Story & Novel",90,"story-novel",{"id":14,"doc_module":4,"doc_module_name":9,"category_name":15,"show_sort_weight":16,"slug":17},2,"Literature",80,"literature",{"id":19,"doc_module":4,"doc_module_name":9,"category_name":20,"show_sort_weight":21,"slug":22},4,"Exam",70,"exam",{"id":24,"doc_module":4,"doc_module_name":9,"category_name":25,"show_sort_weight":26,"slug":27},5,"Comic",60,"comic",{"id":29,"doc_module":4,"doc_module_name":9,"category_name":30,"show_sort_weight":31,"slug":32},6,"Technology",50,"technology",{"id":34,"doc_module":4,"doc_module_name":9,"category_name":35,"show_sort_weight":36,"slug":37},7,"Healthcare",40,"healthcare",{"id":39,"doc_module":4,"doc_module_name":9,"category_name":40,"show_sort_weight":41,"slug":42},8,"Research & Report",30,"research-report",{"id":44,"doc_module":4,"doc_module_name":9,"category_name":45,"show_sort_weight":46,"slug":47},9,"Religion & Spirituality",20,"religion-spirituality",{"id":46,"doc_module":4,"doc_module_name":9,"category_name":49,"show_sort_weight":46,"slug":50},"World Cup","world-cup",{"id":52,"doc_module":4,"doc_module_name":9,"category_name":53,"show_sort_weight":52,"slug":54},10,"Lifestyle","lifestyle",{"id":56,"doc_module":4,"doc_module_name":9,"category_name":57,"show_sort_weight":24,"slug":58},19,"General","general",{"code":4,"msg":60,"data":61},"ok",{"site_id":62,"language":63,"slug":64,"title":65,"keywords":66,"description":67,"schema_data":68,"social_meta":123,"head_meta":125,"extra_data":127,"updated_unix":129},105,"en","time-temperature-transformation-ttt-diagrams-determination-methods-and-salt-bath-procedure","Time Temperature Transformation (TTT) Diagrams - Determination Methods and Salt Bath Procedure","","Time-temperature-transformation (TTT) diagrams describe the kinetics of isothermal phase transformations, including pearlite, bainite, and martensite, in eutectoid steel. The work outlines the historical development of TTT diagrams and enumerates multiple experimental and analytical approaches, emphasizing salt-bath techniques with metallography and hardness as both popular and accurate. It details a three-bath isothermal procedure, defines transformation start and finish times (1% and 99%), and explains martensite start/finish temperatures based on dark and bright etching after tempering and water quenching. Transformation fraction is then plotted against temperature-time on a logarithmic scale to obtain the characteristic S- or C-shaped TTT curve.",{"@graph":69,"@context":122},[70,84,105],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":40,"@type":76,"position":81},"https://docshare.wps.com/document/research-report/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/time-temperature-transformation-ttt-diagrams-determination-methods-and-salt-bath-procedure/657734/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":99,"encodingFormat":97,"isAccessibleForFree":100,"interactionStatistic":101},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/time-temperature-transformation-ttt-diagrams-determination-methods-and-salt-bath-procedure/657734.png","ImageObject",300,407,{"name":92,"@type":93},"Dipper","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-10-30","2026-10-26",true,{"@type":102,"interactionType":103,"userInteractionCount":81},"InteractionCounter",{"@type":104},"ViewAction",{"@type":106,"mainEntity":107},"FAQPage",[108,114,118],{"name":109,"@type":110,"acceptedAnswer":111},"What does a TTT diagram represent in steel transformations?","Question",{"text":112,"@type":113},"TTT diagrams give the kinetics of isothermal transformations. They relate the fraction of phases to temperature and time under constant-temperature holding.","Answer",{"name":115,"@type":110,"acceptedAnswer":116},"Which methods are used to determine TTT diagrams?",{"text":117,"@type":113},"Methods listed include salt bath with metallography and hardness, dilatometry, electrical resistivity, magnetic permeability, in situ diffraction (X-ray/neutron), acoustic emission, thermal measurements, density measurement, and thermodynamic predictions.",{"name":119,"@type":110,"acceptedAnswer":120},"How is the salt-bath technique performed for eutectoid steel in this procedure?",{"text":121,"@type":113},"Samples are austenitised in Salt bath I at the austenitising temperature, transferred to Salt bath II at the specified transformation temperature for various times, then water quenched after holding. The microstructure is examined to quantify phases.","https://schema.org",{"og:url":83,"og:type":124,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":126,"canonical":83},"index,follow",{"doc_id":128,"site_id":62},657734,1792987708,{"code":4,"msg":5,"data":131},{"doc_id":128,"user_id":132,"nickname":92,"user_avatar":133,"doc_module":4,"category_id":39,"category_name":40,"doc_title":65,"doc_description":67,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":81,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":139,"language":140,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":141,"faqs":142,"seo_title":143,"seo_description":67,"update_tm":129,"read_time":144},1374404997633,"https://ap-avatar.wpscdn.com/davatar_a8503ba1806abce46bf441b54a3ca4cd","Time Temperature Transformation  \n(TTT) Diagrams  \nR. Manna  \nAssistant Professor  \nCentre of Advanced Study Department of Metallurgical Engineering  \nInstitute of Technology, Banaras Hindu University  \nVaranasi-221 005, India  \n[rmanna.met@itbhu.ac.in](rmanna.met@itbhu.ac.in)  \nTata Steel-TRAERF Faculty Fellowship Visiting Scholar Department of Materials Science and Metallurgy  \nUniversity of Cambridge, Pembroke Street, Cambridge, CB2 3QZ  \n[rm659@cam.ac.uk](rm659@cam.ac.uk)  \nTTT diagrams  \nTTT diagram stands for “time-temperature-transformation” diagram. It is  \nalso called isothermal transformation diagram  \nDefinition: TTT diagrams give the kinetics of isothermal  \ntransformations.  \nDetermination ofTTT diagram for eutectoid steel  \nDavenport and Bain were the first to develop the TTT diagram of eutectoid steel. They determined pearlite and bainite portions whereas Cohen later modified and included M S and MF temperatures for martensite. There are number of methods used to determine TTT diagrams. These are salt bath (Figs. 1- 2) techniques combined with metallography and hardness measurement, dilatometry (Fig. 3), electrical resistivity method, magnetic permeability, in situ diffraction techniques (X-ray, neutron), acoustic emission, thermal measurement techniques, density measurement techniques and thermodynamic predictions. Salt bath technique combined with metallography and hardness measurements is the most popular and accurate method to determine TTT diagram.  \nFig. 1 : Salt bath I-austenitisation Fig. 2 : Bath II low-temperature  \nheat treatment. salt-bath for isothermal treatment.  \nFig . 3(a): Sample and fixtures for dilatometric measurements  \nFig. 3(b) : Dilatometer equipment  \nIn molten salt bath technique two salt baths and one water bath are used. Salt bath I (Fig. 1) is maintained at austenetising temperature (780˚C for eutectoid steel) . Salt bath II (Fig. 2) is maintained at specified temperature at which transformation is to be determined (below Ae1), typically 700-250° C foreutectoid steel. Bath III which is a cold water bath is maintained at room temperature.  \nIn bath I number of samples are austenitised at AC1+20-40 C for eutectoid and hypereutectoid steel, AC3+20-40 C for hypoeutectoid steels for about an hour. Then samples are removed from bath I and put in bath II and each one is kept for different specified period of time say t 1 , t2 , t3 , t4 , tn etc. After specified times, the samples are removed and quenched in water. The microstructure of each sample is studied using metallographic techniques. The type, as well as quantity of phases, is determined on each sample.  \nThe time taken to 1% transformation to, say pearlite or bainite is considered as transformation start time and for 99% transformation represents transformation finish. On quenching in water austenite transforms to martensite.  \nBut below 230 C it appears that transformation is time independent, only function of temperature. Therefore after keeping in bath II for a few seconds it is heated to above 230 C a few degrees so that initially transformed martensite gets tempered and gives some dark appearance in an optical microscope when etched with nital to distinguish from freshly formed martensite (white appearance in optical microscope) . Followed by heating above 230 C samples are water quenched. So initially transformed martensite becomes dark in microstructure and remaining austenite transform to fresh martensite (white) .  \nQuantity of both dark and bright etching martensites are determined. Here again the temperature of bath II at which 1% dark martensite is formed upon heating a few degrees above that temperature (230 C for plain carbon eutectoid steel) is considered as the martensite start temperature (designated MS) . The temperature of bath II at which 99 % martensite is formed is called martensite finish temperature ( MF) .  \nTransformation of austenite is plotted against temperature vs time on a logarithm scale to obtain th","cbCairBtx0QKbSSG","https://ap.wps.com/l/cbCairBtx0QKbSSG","pdf",4951607,108,"English","# Definition and purpose of TTT diagrams\n## Historical development\n## Methods to determine TTT diagrams\n## Salt bath isothermal procedure\n## Transformation times and martensite MS/MF\n## Building the TTT diagram and curve shape","[{\"question\":\"What does a TTT diagram represent in steel transformations?\",\"answer\":\"TTT diagrams give the kinetics of isothermal transformations. They relate the fraction of phases to temperature and time under constant-temperature holding.\"},{\"question\":\"Which methods are used to determine TTT diagrams?\",\"answer\":\"Methods listed include salt bath with metallography and hardness, dilatometry, electrical resistivity, magnetic permeability, in situ diffraction (X-ray/neutron), acoustic emission, thermal measurements, density measurement, and thermodynamic predictions.\"},{\"question\":\"How is the salt-bath technique performed for eutectoid steel in this procedure?\",\"answer\":\"Samples are austenitised in Salt bath I at the austenitising temperature, transferred to Salt bath II at the specified transformation temperature for various times, then water quenched after holding. The microstructure is examined to quantify phases.\"}]","Time Temperature Transformation (TTT) Diagrams - Determination Methods and Salt Bath Procedure | PDF",272]