Thread: Ravensthorpe Nickel To Close?

Originally Posted by Brian Hjelm

All "stainless" steels contain chromium. Some contain nickel, some do not. Some "stainless" steels will show rust. The term "Stainless Steel" is a trade name for a cutlery grade patented in early 20th. Century. A more correct term is probably corrosion resistant chromium alloy steels. What do you mean by nickel based and pig iron based? Not all "stainless" steels contain nickel but sure as hell there will be pig iron in them, steel being an alloy of iron and carbon. Perhaps you mean steel made with virgin pig where no scrap has been added to the melt?

It will certainly be difficult for unemployed mine coy. employees to find jobs in North Qld which has just about always been a hot spot for unemployment and low wages. The only major employer in most of North Qld. is the sugar industry. Sugar now, compared to 1959, makes seven times the amount of sugar with half the farmers and two thirds the mills. Mechanical harvesting and bulk handling removed the army of harvest workers, bag handlers and wharfies. The only other major employer in most of the north is tourism. Mine workers generally do not make house maids, waiters and bar attendants.

What was at Hopetoun before the mine? It is a long way from anywhere. If it was just a rural wide spot in the road or a purpose built mining town then what will happen when the mine closes is that it will become another backblocks ghost town like lots of others.

Stainless generally contains steel, nickel and minimum chromium, over recent times the nickel component is starting to be replaced with "pig iron" and as such even the lower grades of SS will reduce. SS production is the biggest consumer of nickle up until this time. Lower grade SS had a higher component of steel and less nickel and even some pig iron, but is a relatively new wide scale addition. Austentic stainless steel is what up until recently accounted for 70% of SS production.

Stainless steels are also classified by their crystalline structure:

• Austenitic, or 300 series, stainless steels comprise over 70% of total stainless steel production. They contain a maximum of 0.15% carbon, a minimum of 16% chromium and sufficient nickel and/or manganese to retain an austenitic structure at all temperatures from the cryogenic region to the melting point of the alloy. A typical composition of 18% chromium and 10% nickel, commonly known as 18/10 stainless, is often used in flatware. Similarly, 18/0 and 18/8 are also available. Superaustenitic stainless steels, such as alloy AL-6XN and 254SMO, exhibit great resistance to chloride pitting and crevice corrosion due to high molybdenum content (>6%) and nitrogen additions, and the higher nickel content ensures better resistance to stress-corrosion cracking versus the 300 series. The higher alloy content of superaustenitic steels makes them more expensive. Other steels can offer similar performance at lower cost and are preferred in certain applications.[citation needed]

The low carbon version of the Austenitic Stainless Steel, for example 316L or 304L, are used to avoid corrosion problem caused by welding. The "L" means that the carbon content of the Stainless Steel is below 0.03%, this will reduce the sensitization effect, precipitation of Chromium Carbides, due to the high temperature produced by welding operation.

• Ferritic stainless steels are highly corrosion-resistant, but less durable than austenitic grades. They contain between 10.5% and 27% chromium and very little nickel, if any, but some types can contain lead. Most compositions include molybdenum; some, aluminium or titanium. Common ferritic grades include 18Cr-2Mo, 26Cr-1Mo, 29Cr-4Mo, and 29Cr-4Mo-2Ni.

• Martensitic stainless steels are not as corrosion-resistant as the other two classes but are extremely strong and tough, as well as highly machineable, and can be hardened by heat treatment. Martensitic stainless steel contains chromium (12-14%), molybdenum (0.2-1%), nickel (0-<2%), and carbon (about 0.1-1%) (giving it more hardness but making the material a bit more brittle). It is quenched and magnetic.

• Precipitation-hardening martensitic stainless steels have corrosion resistance comparable to austenitic varieties, but can be precipitation hardened to even higher strengths than the other martensitic grades. The most common, 17-4PH, uses about 17% chromium and 4% nickel. There is a rising trend in defense budgets to opt for an ultra-high-strength stainless steel when possible in new projects, as it is estimated that 2% of the US GDP is spent dealing with corrosion. The Lockheed-Martin Joint Strike Fighter is the first aircraft to use a precipitation-hardenable stainless steel—Carpenter Custom 465—in its airframe.

• Duplex stainless steels have a mixed microstructure of austenite and ferrite, the aim being to produce a 50/50 mix, although in commercial alloys, the mix may be 40/60 respectively. Duplex steels have improved strength over austenitic stainless steels and also improved resistance to localised corrosion, particularly pitting, crevice corrosion and stress corrosion cracking. They are characterised by high chromium (19–28%) and molybdenum (up to 5%) and lower nickel contents than austenitic stainless steels. The most used Duplex Stainless Steel are the 2205 (22% Chromium, 5% Nickel) and 2507 (25% Chromium, 7% Nickel) sometimes the 2507 is also called "SuperDuplex" due to the higher Corrosion resistance.

Life is the proverbial Rollercoaster...nothing stays the same forever.....2yrs this will all be a bad episode/memory I just hope all the years on the good money wasn't pizzed up against the wall by all the miners and they can weather the global storm.