SUMMER 2019

14 THE DISTRIBUTOR’S

14 THE DISTRIBUTOR’S LINK Guy Avellon Guy Avellon has been in MRO and Fastener Distribution for over 30 years, in such positions Sales Engineer, Chief Engineer, Manager of Product Marketing, Product Engineering & Quality and Director of Quality & Engineering. He founded GT Technical Consultants where he performs failure analysis, lectures on fastener safety, works for law firms and designs/audits Quality systems. He is a member of SAE, is Vice Chairman of the ASTM F16 Fastener Committee, Chairman of the F16.01 Test Methods Committee and received the ASTM Award of Merit in 2005. Guy can be contacted at 847- 477-5057, Email: ExpertBoltGuy@gmail.com or visit www.BoltFailure.com. WHAT FASTENER DISTRIBUTORS NEED TO KNOW ABOUT STEEL IN FASTENERS Many times, we take products for granted. We know one type of fastener should have more strength than another, but how does an engineer know if the steel and heat treatment properties will provide suitable performance for some of the applications they require? As a guide, this article will provide what the steel chemistry numbers mean to users. Carbon steels are called such as they contain a certain amount of carbon. The amount of carbon present determines the steels ability to be heat treatable. The higher the carbon content, the harder the steel becomes when heated. The addition of certain alloying elements will provide the performance characteristics desired of the finished product and reduce brittleness. The base steel or alloy composition type is identified by a series of digits in the steel number, as developed cooperatively by the AISI (American Iron and Steel Institute) and the SAE (Society of Automotive Engineers). For example; the first digit of a four or five digit steel number indicates a category, such as (1) carbon steel, (2) nickel steel, (3) nickel-chromium steel, etc. The second number indicates the approximate percentage of the alloying element, while the last two or three digits indicate the approximate 1/100ths weight percentage of carbon content. Typical AISI/SAE steels, but not limited to, used for fastener products are as follows: ¤ 10xx—Plain Carbon Steel (1010) ¤ 15xx—Manganese Steel (1541) ¤ 40xx—Molybdenum Steel (0.25%) (4037) ¤ 41xx—Chromium-Molybdenum Steel (1.0% Cr, 0.20% Mo) (4140) ¤ 43xx---Chromium-Manganese-Molybdenum Steel (4340) CONTRIBUTOR ARTICLE ¤ 50xx---Nickel Steel (50B46) ¤ 51xx—Chromium Steel (51B60) (0.80% Cr) ¤ 86xx---Chromium-Nickel-Molybdenum Steel (8637) ¤ 87xx—Chromium-Nickel-Molybdenum Steel (0.55% Ni, 0.50% Cr, 0.25% Mo) ¤ 94xx---Nickel-Chromium-Molybdenum Steel (94B40) To be considered an alloy steel, one or more alloying elements must be added to the steel. The American Iron and Steel Institute has defined that a steel is considered to be an alloy when the maximum of the range given for the content of alloying elements exceeds one or more of the following limits: manganese, 1.65%; silicon, 0.60%; copper, 0.60%; or in which a definite minimum quantity of any of the following elements is specified or required within the limits of the recognized field of constructional alloy steels: aluminum, chromium up to 3.99%, cobalt, columbium, molybdenum 0.30%, nickel 0.30%, titanium, tungsten, vanadium 0.10%, zirconium, or any other alloying elements added to obtain a desired alloying effect. Where elements are specified in combinations of two, three or more and have alloy contents less than described above, the limit value to be applied for steel class determination is 70% of the sum of the individual values of the concerned elements. Fastener Grades All fasteners, regardless of standard or specification, are identified by a unique marking on the head, in addition to the manufacturer’s unique registered marking. The following is a typical list of the common inch and Metric fasteners used in commerce. See SAE J429 and SAE J1199. CONTINUED ON PAGE 128