EAF vs Induction Furnace Rebar: Why IWS Premium Rebar Is Made by EAF

Two deformed rebars with the same diameter and the same grade label can come from very different melting processes. In the Indonesian market, some rebar is made from steel melted in induction furnaces, and some from electric arc furnaces (EAF). Stacked in a warehouse, they look alike. The difference only shows up in chemical analysis, tensile tests, and bend tests.

Contractors and project owners rarely ask "how was this steel melted?", yet the answer affects how consistent the quality is from one delivery to the next. This article explains the difference between the two processes honestly, why PT Inter World Steel Mills Indonesia produces its rebar through the EAF route rather than induction furnaces, and how you can verify such claims from any supplier.

Two ways to melt steel from scrap

Both EAF and induction furnaces melt steel scrap using electricity, and both are legitimate in the steel industry. The difference lies in what can be done to the liquid steel after it melts.

Induction furnace: melting, with limited refining

An induction furnace heats metal with an electromagnetic field. The process is relatively simple and the investment is smaller, so it is common among small-scale mills. Its limitation: the slag layer on top of the melt is relatively cool and less reactive, so its ability to remove impurities such as phosphorus and sulfur is limited. As a result, the chemistry of the steel depends heavily on the quality of the scrap charged. Dirty or mixed scrap tends to produce dirty steel.

EAF: melting and refining

An EAF melts scrap with a very high-temperature electric arc, and the process allows oxygen injection and the formation of an active slag. This slag captures part of the impurities so they can be removed from the melt. Before casting, the chemistry is tested and can be adjusted. As a result, the composition of the steel is easier to control and is not determined solely by the incoming raw material.

To be fair: not all induction furnace rebar is necessarily poor, and not all EAF rebar is necessarily good. What matters is still the test result for each batch. But the EAF process provides a more complete set of quality control tools, which is why mills that are serious about consistency choose it.

EAF and induction furnace compared

The production route of IWS Premium Rebar

PT Inter World Steel Mills Indonesia in Tangerang, with more than 50 years of experience, operates an EAF, not an induction furnace. Its production flow, as shown on the Production Flow page, consists of ten stages:

1. Iron and steel scrap as raw material
2. Melting in the Electric Arc Furnace
3. Chemical composition test
4. Billet casting in the Continuous Casting Machine
5. Reheating in the Reheating Furnace
6. Rolling in the Rolling Mills
7. Cooling on the Cooling Bed
8. Visual and mechanical test
9. Packing
10. Delivery

Two test points, the chemical composition test after melting and the visual and mechanical test after rolling, form the basis of IWS Premium Rebar. We should say it plainly: "premium" is not an official SNI term. What we mean is plain (BjTP) and deformed (BjTS) rebar certified to SNI 2052:2024, produced through the EAF route, with a mill certificate for every batch.

How to verify quality, from any supplier

A process claim is not enough. Here are steps you can take yourself before and when the goods arrive.

1. Request documents per batch

Ask for the SPPT-SNI and the mill certificate for the delivered batch. A good mill certificate lists the chemical composition and tensile results: yield strength, tensile strength, and elongation. Our guide on how to read a rebar mill certificate explains each figure. Our mill's certification status is shown on the Certification page.

2. Weigh a few sample bars

Under SNI, weight depends only on diameter: weight (kg/m) = 0.006165 × d². Weigh a few bars and compare them with the table below.

Example: a 12 m D16 bar should weigh about 18.94 kg. If it weighs only 17.0 kg, it is about 10.2% light, and its effective cross-section is equivalent to a bar of roughly 15.2 mm diameter. Other signs of undersized rebar are covered in our article on how to spot undersized rebar.

3. Check markings and consistency

SNI rebar carries mill and size markings on the bar. Also check the uniformity of the ribs, straightness, and surface condition. Bars that crack when bent on site are a warning sign that should be reported to the supplier.

Frequently Asked Questions

Is induction furnace rebar prohibited?

SNI regulates the quality of the final product, not only the type of furnace. Any rebar sold must meet SNI 2052:2024. That is why batch test results remain the main reference, whatever the melting process.

Why is the EAF process considered better for rebar?

Because an EAF allows refining: part of the impurities can be removed through slag, and the chemistry is tested and adjusted before casting. This makes quality more consistent and less dependent on scrap quality alone.

How do I know the rebar I buy comes from an EAF?

Ask the supplier directly which mill produced the rebar, then request a mill certificate per batch showing the chemical composition and tensile test. A supplier who cannot show these documents deserves questions.

Is IWS Premium Rebar more expensive?

Steel prices move with raw materials and exchange rates, so we do not publish prices in articles. Contact our sales team for a quotation based on diameter, grade, and project volume.

Which grades are available?

IWS produces plain rebar (BjTP 280) and deformed rebar (BjTS 420, BjTS 520, BjTS 550). Diameter availability and stock for a specific grade can be confirmed with our sales team.

Order EAF rebar directly from the mill

If your project needs rebar with consistent quality from batch to batch, complete with SPPT-SNI and mill certificates, our team is ready to help calculate your needs and check stock. Send your requirements through the Order Now page for a quotation, or call our sales team at (+62 21) 6570 3888.