Elongation % requirements for rebar

Elongation % requirements for rebar

Elongation Requirements for Stainless Steel Rebar Presented by: Suresh Gupta ASTM Committee Meeting A01.05 May 8, 2012

Purpose of Elongation Elongation is a measure of ductility, which provides confidence that metals can be formed, without cracking or fracturing. In rebar, it defines ductility so that bars can be bent without cracking. If bars do not crack during fabrication, any excess

elongation is irrelevant. Alloy Characteristics With all other variables remaining same, Austenitic Alloys have highest elongation. Duplex Alloys have elongation in mid range Ferritic Alloys have lowest elongation

Measurement Methods and Facts % Elongation, when measured in a fixed gage length, e.g. 8 inches, is lower than when measured in a gage length, as a multiple of diameter, e.g. 4 X diameter (4d). (when 4d is less than fixed gage length). Elongation is generally lower as diameter goes

smaller. This fact is clearly described in ASTM E8, Appendix XI ASTM E8 Standard Test Method for Tension Testing of Metallic Materials Appendix XI Factors Affecting Tensile Test Results Comparison of elongation values determined using different

specimens requires that the following ratio be controlled: Lo/(Ao)1/2 (XI.1) Where: Lo = original gage length of specimen, and Ao= original cross-sectional area of specimen. XI.4.4.1 Specimens with smaller Lo/(Ao)1/2 ratios generally give greater elongation.

Note: (Ao)1/2 is proportional to diameter (d). Therefore, for same ductility, larger diameter samples result in greater elongation values, when measured in fixed gage length. ASTM A955-9a Until revision 10a, elongation was not required for sizes # 3-5 Grade 75, probably because it was known that it is unrealistic or not necessary.

Grade 40 for sizes 7 and larger because, in any condition it will meet the requirement, anyway. % Elongation Requirements for Rebar Carbon and Alloy steels ASTM A615 requires 6 to 7% for Grade 75 ASTM A706 requires 10 to 14% for all Grades. Stainless Steels

BS 6744 requires 14% minimum in 5d gage length for Grade 500 (72.5 ksi). ASTM A955 requires 20% minimum in 8 inch gage length for all grades, all sizes. Manufacturing & Process Control Even with precise chemistry and process

control, duplex stainless steels meet the elongation requirement very marginally. If rebar is supplied in coils, machine straightening will cause work hardening and elongation will go down even further. This may cause unnecessary dispute.

Rationale If 6% elongation in carbon steel is sufficient If 14% in 5d is sufficient for stainless steel rebar per BS6744 in Europe, It should be sufficient for us as well. FYI ASTM Specifications for plain smooth bars

require elongation in 4d Proposal It is therefore recommended that, Using a foot note to Table 3, elongation requirements be lowered to 14% for Grade 75, for all sizes of duplex grades and, all grades of stainless steels under 1.00 inch.

Recently Viewed Presentations

  • Mid Quadrant Management Structure and Contact Details Nicky

    Mid Quadrant Management Structure and Contact Details Nicky

    Local Delivery Mid 01245 434816 Leads: Permanence Strategy Health of CIC Strategic lead on CIC and Leaving Care Lynne Hooper Service Manager Assessment & Intervention (A&I) Mid 01245 434037 Russell Coward Service Manager Family Support & Protection (FS&P) Mid 01245...
  • Слайд 1

    Слайд 1

    Синтез маркетинговых исследований: когда 1+1>2 Конференция «Фарм Бюджет 2010»» Игорь Крячок
  • History - moodlearn.ariel.ac.il

    History - moodlearn.ariel.ac.il

    Arrays & structs as arguments. When an array is passed as an argument to a function, the address of the 1st element is passed. Structs. are passed . by value, exactly as the basic types. Array == (in run time)...
  • Chapter 3

    Chapter 3

    , Chinooks, Kwakiutls. Artifacts: (possible answers) • wood house with cedar totem poles: constructed. from local cedar trees • waterproof cedar-bark clothing: used plentiful. cedar bark for protection against rain • cedar and willow fish trap: made from local. cedar...
  • www.crcv.ucf.edu

    www.crcv.ucf.edu

    n automatic metric for machine translation evaluation that is based on a generalized concept of unigram matching between the machine-produced translation and human-produced reference translations. computing a score based on explicit word-to-word matches between ... hockey. They are playing a...
  • Climate Risk Management and Sharing: Bringing insurance ...

    Climate Risk Management and Sharing: Bringing insurance ...

    Utilising insurance industry tools to underpin cost-effective adaptation ... Efficient weather-related food security risk management through risk pooling and sharing across regions Africa RiskView Software Platform: A financial management tool for decision makers Climate Change Stress Tests ...
  • Electric Current and Resistance

    Electric Current and Resistance

    acts as one way valve turning AC into pulsed DC. 2 or more diodes together can provide smoother DC . Capacitors also used to smooth out DC signal. Most electronic devices need DC to operate, so they must have a...
  • Evaluation Procedures Brian Lines, Ph.D Assistant Professor University

    Evaluation Procedures Brian Lines, Ph.D Assistant Professor University

    escalation letter. meet & greet… perhaps for the FIRST time??? INSTEAD, we should try to… - contractors explain that they need from and why - get more detailed - set the expectations [align expectations] - "did you guys really want...