Industrial Consultancy & Sponsored Research (IC&SR) , IIT Madras
Method of Testing ‘Quenched and Self-tempered (QST)’ or ‘Thermo-mechanically Treated (TMT) Steel Reinforcing Bars
Categories for this Invention
Category: Civil Infrastructures & Structural Engineering
Industry: Research Institution ,Construction and Manufacturing.
Application: Quality checks at both the steel plant and construction site.
Market: The global Civil infrastructure market Size estimated at USD 8.7 Trillion in 2022 and is projected to reach USD 15.4 Trillion by 2032, registering a CAGR of 5.9% during the forecast period from 2023 to 2032.
Image Gallery
Problem Statement
- The Thermo-Mechanically Treated (TMT) steel are scientifically known as Quenched and Self Tempered (QST) steel.
- The cross-section of good TMT/QST steel reinforcing bars (rebars) should have a ductile core of ‘ferrite-pearlite’ (FP) and a continuous and uniformly thick peripheral ring of hard ‘tempered martensite’ (TM) microstructure.
- However, recent studies on TMT/QST steels in the Indian market observed the presence of discontinuous, eccentric, and non-uniform TM-phases at the periphery, which can be attributed to the improper quenching.
- This could result in localized corrosion and variations in the mechanical properties as per IS 1786: 2008.
- In this scenario, a standardized test is essential to assess the quality of TMT/QST steel rebars.
Technology
- Test method for the quality control of steel reinforcing bars used in concrete structures using macroetching and imaging procedures
PURPOSE:
- A standard test-setup and output qualification procedure as a small-scale lab test for “offline” quality control testing of microstructural phase distribution in steel rebar cross-sections (not surface).
CONVENIENCE:
- Visual qualification criteria and reference images for recommended phase distribution. Quantification procedure for stringent and detailed analysis of the etched output.
TEST SETUP:
- Table-top test frame with preset procedure for reproducible results in terms of lighting. Image scale with respect to the overall photo-frame (standardization and output categorization for quality needs).
Method of testing steel reinforcing bars (steel rebar) comprising the steps of:
- The specimen is accepted only if the specimen image satisfies visual analysis, wherein the specimen satisfies the visual analysis only if it meets all of the following conditions:
Key Features / Value Proposition
- A custom design of ‘small-scale’ lab-test setup.
- Minimal etching and corrosion exposure to the final product.
- Stand-alone lab-scale test Setup for etching in 5% Nital (5% nitric acid and ethanol).
- Representative sample test for quality control to avoid intentional corrosion of final product.
- 2-level qualification procedure –Level 1 as phase distribution categorization with reference images for an exhaustive list of output cases.
- Level 2 as a quantification process of phase distribution for in-line process modification or advanced analysis.
- Data acquisition based on a preset detailed step-by-step procedure like (Specimen extraction, Specimen preparation for testing, Specimen testing on “TM-ring test” setup).
- Post-test output qualification and quantification for quality control.
- Post-scan/photograph quality assessment protocol with reference output cases for visual comparison and quantifying technique identified for evaluating the quality of phase distribution.
- Exhaustive output cases with experimental issues introduced for reference output.
- An easy and fast testing (within 5 minutes)
- High quality products by testing the corrosion resistance of the steel specimens,
- Prevent air pollution by discharging fume generated during the test after the fume is neutralized below a reference value.
- Facilitating the stakeholders to perform quality checks at both the steel plant and construction site.
Questions about this Technology?
Contact For Licensing
sm-marketing@imail.iitm.ac.in
ipoffice2@iitm.ac.in
Research Lab
Prof.Radhakrishna G Pillai
Department of Civil Engineering
Intellectual Property
- IITM IDF Ref. 1566
- Patent No: IN 533772
Technology Readiness Level
TRL – 4
Technology validated in lab scale.