Tempcore Properties
Chemical Composition - Generally as per IS 1786:1985. However we maintain Carbon equivalent value to maximum 0.45%. (British Standard specifies 0.51% for grade 460).Carbon equivalent is determined by the following formula: Cequiv = C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15.
Bend Properties - Easily satisfy International Standards. In India Bend & Rebend Tests are mainly carried out as per Indian 1786 & British 4449 standards. BHAGWATI TMT bars meet all such requirements.
| Test | IS 1786 Fe 415 | Bhagwati 415 | IS 1786 Fe 500 | Bhagwati 500 |
| Bend | 3d (4d for>22 dia) | 2d | 4d (5d for>22dia) | 3d |
| Rebend | 5d (7d for>10 dia) | 4d | 5d (7d for>10dia | 5d |
Weldability - Bhagwati TMT bars are produced with C less than 0.25% an are suitable for all the main welding processes without any special precautions. No pre-heating or post-heating is necessary. No loss of strength at weld- joints.
Strain Ageing - Ageing resistant due to the manufacturing process and chemical composition.
Fatigue - Approved internationally for dynamically stressed structural sections.
Properties at High Temperatures - Tempcore / Thermex bars, unlike CTD bars, have a proven record resisting loss of strength at high temperatures as experienced during fires.
Corrosion Resistance - More corrosion resistant than CTD bars. Cold working involved in CTD bars leads to surface stresses and consequent higher rate of corrosion - and, the protective scale layer falls off during twisting. Tempcore / Thermex process basically inhibits rate of scale formation an no cold working is involved.
Tempcore Grades
| Bhagwati Thermex / Tempcore 415 | ||
| Properties | Standard IS 1786, Fe 415 | Bhagwati |
| Yield Strength, N/mm2, min | 415 | 430 - 460 |
| Tensile Strength, N/mm2, min | 485 | 500 - 570 |
| Stress Ratio (TS/YS), min | 1.13 | 1.15 - 1.25 |
| Elongation, % min’ | 14.5 | 20 - 24 |
| Bhagwati Thermex / Tempcore 500 | ||
| Properties | Standard IS 1786, Fe 500 | Bhagwati |
| Yield Strength, N/mm2, min | 500 | 520 - 550 |
| Tensile Strength, N/mm2, min | 560 | 590 - 570 |
| Stress Ratio (TS/YS), min | 1.10 | 1.15 - 1.24 |
| Elongation, % min’ | 12 | 18 - 12 |
Tempcore Benefits
- Lowers Steel Consumption
- International uality Steel product at local affordable prices
- High weldability and ductility
- High yield strength with high elongation
- High thermal stability
- Ease of availability
- Better corrosion resistance
- Higher Grades easily available ( Fe 400, Fe 400D, Fe 500, Fe 500D, Fe 550, Fe 550D)
- Better resistance of fatigue
- Higher bond strength
- Higher resistance to strain Aging
- Availability of International grades
- Ease of use leading to less construction time
- Most suited for seismic zones as nearly 60% of India falls in high seismic hazard category
Tempcore Technology
The TEMPCORE Process has been developed in the early seventies by C.R.M., Belgium in order to manufacture high yield strength weldable concrete reinforcing bars from mild steel, without V or Nb additions : the Tempcore rebars.
It consists in subjecting the hot rolled steel to an in-line heat treatment in 3 successive stages :
Stage1 - As soon as it leaves the final mill stand, the product is rapidly and energetically cooled through a short cooling installation, where it undergo surface hardening (martensite layer).
Stage2 - As soon as this quenching operation is stopped, the surface layer is Tempered by using the residual heat left in the CORE of the bar (self tempering of the martensite layer) ; hence the name Tempcore.
Stage3 - The third stage takes place while the product lies on the cooling bed where the bar is subjected to normal cooling down to ambient temperature (transformation of the residual austenite in the core.
Tempcore is the Best Process for the Production of High Quality Rebars: Costly alloying elements (Vanadium, Niobium) are replaced by low-cost water, in order to obtain from low C-Mn steel, concrete reinforcing bars with :
- High mechanical properties (DIN 488 IVS, Fe500, BS4449-97, ...)
- Excellent weldability
- Excellent ductility and bendability
Comparison
| Bhagwati Thermex / Tempcore Bar Vs Others | ||||
| Properties | Duplicate TMT | CTD bars/TOR | Main Producers | Bhagwati |
| Strength | Lower than CTD/TOR | Avg (Normally upto Fe 415 grade) | High (Grade Fe 500 is easily available) | High (Grade Fe 500 is easily available) |
| Elongation | Non - standard | Approx 14.5% | High | High; 18 - 25% in all grades |
| Weldability | Very Weak | Weak | Better & more strength | Better & more strength |
| Formability | Non - standard | Average | Excellent due to uniform elongation | Excellent due to uniform elongation |
| Technology | Unscientific method | Indian | Tempcore/ Thermex (Belgium / German) | Tempcore/ Thermex (Belgium / German) |
| Ductility & Fatigue Strength | Non - standard | Average | High | High-most appropriate for earthquake prone areas |
| Corrosion Resistance | Very low | Low | High | High |
| Ribs | Manual & Non-uniform | Manual & Non-uniform | Computerised & Uniform |
Computerised & Uniform |
| Savings | Very High Steel consumption due to unscientific methods | Nil | No saving due to higher prices | 8-15% compared to CTD bars / Main Producers |
| Availability | Non - Consistent | Available | Irregular Supply | Easily available through network |
| Price | Very cheap due to low quality | Cheap due to outdated technology | Very high Price for the same Quality | Much lower than main producers for the same quality |
