Production Machining

NOV 2018

Production Machining - Your access to the precision machining industrial buyer.

Issue link: https://pm.epubxp.com/i/1041107

Contents of this Issue

Navigation

Page 18 of 51

productionmachining.com :: 17 ,ĞůƉŝŶŐWƌĞĐŝƐŝŽŶDĂĐŚŝŶĞ^ŚŽƉƐĞDŽƌĞWƌŽĚƵĐƟǀĞĂŶĚWƌŽĮƚĂďůĞ Technical Regulatory Management Quality Technical Regulatory Management Quality Craftsman's Cribsheet DŝůĞƐ&ƌĞĞʹŝƌĞĐƚŽƌŽĨ/ŶĚƵƐƚƌLJZĞƐĞĂƌĐŚĂŶĚdĞĐŚŶŽůŽŐLJ NUMBER 71 A Quick Guide to the Chemical Elements Found in Steel CHEMICAL ELEMENT 5;/$1. WHAT DOES IT DO FOR THE STEEL PERFORMANCE WHAT DOES IT DO FOR MACHINING WHAT STEPS TO TAKE WHEN ;17'0%1706'46*+5 Carbon C Strengthens, hardens, makes heat treatable. Improves up to ~0.23%. Gives steel its hardness. Anneal if over 0.40% and alloy steel; if carbon steel and over 0.50%. Manganese Mn Strengthens, hardens, enhances heat treatment. Improves surface and machinability. No special techniques needed. Promotes machining. Phosphorus P Ferrite strengthener. Lowers ductility. Crisps up chip. Improves ÃÕÀv>Viwð Be careful with subsequent cold work on rephosphorized steels. Sulfur S Lowers ductility, toughness, weldability, surface quality. Controls built up edge (BUE), improves machinability about 25%. Increase speeds and feeds. Is machinist's friend.* Silicon Si Deoxidizer, makes steel sound. May degrade surface quality. Abrasive on tools. Want 0.01-0.02 max silicon in 12XX steels; 0.10 max Si for 11XX for best machinability. Copper Cu Negligible in our applications. Usually it is a clue about how steel is made. Higher coppers tend to indicate electric furnace steel. Nickel Ni Ferrite strengthener. Aids heat treatment. Usually makes chips tough to separate. Avoid dwell. Sharpen tools. Secure workholding. Chromium Cr Corrosion resistance, high temperature strength and heat treatability. Higher strength makes >V}Ài`vwVÕÌ° Can be abrasive. Pay attention to tool edges and wear. Molybdenum Mo Increases hardenability, raises tempering temperatures. Not noticeable. No special precautions. Aluminum Al iÛi«Ãwi>ÕÃÌiÌV grain size. Can combine with nitrogen. Decreases tool life. Pay attention to tool edges and wear. Lead Pb No effect on mechanical properties. Promotes machinability about 25%. Run at higher productivity. Take advantage of this. Columbium (Niobium) Cb / Nb À>ÀiwiÀÕ«Ìä°äx¯ bars. Microalloy strengthener. ->ÀÌƂ>Ã}À>ÀiwiÀ° As microalloy, makes material harder and tougher to machine. Pay attention to tools, understand condition if microalloy. Vanadium Va À>ÀiwiÀ>`ÃÌÀi}ÌiiÀ° Microalloy in forging steels. Decreases tool life. Harder ÃÌiiÃÀi`vwVÕÌÌVÕÌ° Pay attention to tools, understand condition if microalloy. Bismuth Bi No strengthening effects. Possible embrittlement. Improves machining. Substitute for lead. Run at higher productivity. Take advantage of this. Nitrogen N Strengthener and lowers ductility (notch toughness). «ÀÛiÃÃÕÀv>ViwÃ>` promotes chipbreaking. Crisper chip and improved sur- v>Viwð Does not like to be cold worked. Avoid dwell, avoid in crimping applications. I-ÕvÕÀ\*>V>ÀL>`>ÞÃÌiiÃÜÌÃÕvÕÀLiÜä°ä£äÜ̯>Ài«ÀLi>ÌVvÀ>V}>`ÃÕÀv>Viwðä°äÓÜ̯ minimum sulfur is optimum in these steels for machining. This handy quick guide will give you the common chemical elements found in steel, how they affect steel properties and the machining process and a few tips on how to deal with them. All Craftsman's Cribsheets are available for viewing and download at pmpa.org/knowledge-tools/craftsmans-cribsheets.

Articles in this issue

Links on this page

Archives of this issue

view archives of Production Machining - NOV 2018