445M2 Stainless Steel – Use of Stainless Steel Grade 445M2 in a Nickel Smelter by Austral Wright Metals


Modern Industries (WA) in Western Australia is a business that lives up to its name. Modern recently completed a major contract for BHP Billiton’s Ravensthorpe Nickel Project using new generation ferritic stainless steel 445M2 from Austral Wright Metals and Nisshin Steel, Japan, for cladding insulation at the sulphuric acid plant at Ravensthorpe. Modern Industries have built an enviable track record in Australia and South East Asia providing construction and maintenance services to the mining, energy, oil and gas industries, particularly thermal and acoustic engineering solutions – based on delivering on promises, and working out how to do it better.

Stainless Steel 445M2 – An Alternative to 316 Stainless Steel

Modern Industries Director Steve Skea evaluates his experience with stainless steel 445M2: “We were looking for a better alternative to the familiar marine grade stainless steel 316. Austral Wright Metals offered us stainless steel 445M2, and convinced us of the better atmospheric corrosion performance. That was important, because although the Ravensthorpe project is 46 km from the ocean, so salt isn’t the problem, we were insulating a sulphuric acid plant – and that’s definitely an arduous service for stainless steel.

Advantages of 445M2 Stainless Steel over 316 Stainless Steel

We found the new grade very easy to work with – it saved us money in time and rework while we were pre-fabricating in our workshop in Perth. The extra precision we got in the pre-fabs was also a great help when we got out on site at Ravensthorpe, 500 km east of here. We moved from 316 and stainless steel 445M2 over the life of the job, so we got a fair comparison between the grades. We had no issues in switching to stainless steel 445M2, and we’ll use it again for this sort of job – and anywhere else where we used to use 316.”

BHP Billiton Helps Satisfy Global Demand for Nickel

Austral Wright Metals and Modern Industries are proud to have made a small contribution to Australia’s mining boom. Australian exports of nickel alone have grown from A$2.5B to A$8B over the last two years – because the insatiable demand from China has increased nickel prices many times over. Now the Ravensthorpe Nickel Project is set to add another A$1.5B to the total. That’s adding about 1% to Australia’s total exports – not bad for a single project.

BHP Billiton Ravensthorpe Nickel Project

But it’s not so easy for BHP Billiton to add that much to our national wealth. The ore at Ravensthorpe is a laterite – it contains nickel oxide, cheaper to mine but much harder to process than the sulphide ores older projects use. Processing requires leaching with sulphuric acid in a high temperature and pressure autoclave to dissolve the nickel. The autoclaves are titanium lined for acid resistance, and use a mixture of ore slurry and sulphuric acid at up to 290ºC and 8,500 kilopascals of pressure – that’s 8½ times atmospheric pressure.

The Ravensthorpe plant will consume 500,000 tonnes per year of sulphur, used to make the sulphuric acid needed to treat 13 million tonnes of ore a year. The sulphur is imported from Canada and the Middle East, and burnt to produce sulphuric acid in the plant Modern Industries made their contribution to. Without sulphuric acid, the plant cannot work, so the acid plant is a key element.

The Increasing Global Demand for Nickel

About 65% of nickel used world-wide is in stainless steel, and it’s the growth in demand for stainless steel by China and other developing countries that has fuelled the growth in demand for nickel.

445M2 - The New Marine Grade Stainless Steel

445M2 Stainless Steel – A Nickel-Free Stainless Steel

Ironically, stainless steel 445M2 is a modern stainless steel that does not contain nickel, unlike the better known austenitic stainless steel grades like 304 and 316. Instead, Nisshin Steel in Japan use modern, state-of-the- art vacuum processing steelmaking technology to produce a premium stainless steel without an expensive addition of nickel. Demand for nickel is also growing strongly for nickel metal hydride electrical storage cells, used for highly fuel-efficient hybrid cars like the Toyota Prius and the Honda Civic Hybrid. So demand for nickel is not likely to drop – and nickel is making its contribution to slowing global warming.

Chemical Composition of 445M2 Stainless Steel

Table 1. The chemical composition of 445M2 stainless steel compared to 316 stainless steel.











Nb and Ti







Corrosion Resistance of 445M2 Stainless Steel

Stainless steel 445M2 is a marine grade stainless steel with the corrosion resistance of 316 – or better. It resists sea salt for safe performance over a long life. Unlike grade 316,  stainless steel 445M2 has a ferritic microstructure and a full 22% of the corrosion-resisting element, chromium.

Fabrication with 445M2 Stainless Steel

Stainless steel 445M2 is easier to fabricate than grade 316. As a premium ferritic grade, 445M2 has excellent punchability, bendability and weldability.

A much lower rate of work hardening gives lower forming loads and less springback. 445M2 behaves like carbon steel - cleaner cuts, less distortion, longer tool life and cost savings.

Available Forms from Austral Wright

Stainless steel 445M2 is available from stock as sheet & coil in 0.55, 0.7, 0.9, 1.2, 1.5, 2.0, 2.5 & 3.0 mm thickness in 2B & No4 finish, all 1219 mm wide. For architectural applications 0.55 x 940 mm with the low reflectivity 2DR finish is available.

Source: Austral Wright Metals

For more information on this source please visit Austral Wright.

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