Japanese HSLA shipbuilding steel development

Cited as the motivation for Tom's mid-1980s Japan trip on behalf of the Navy. Japanese commercial steel mills were producing one-inch plate that required no summer preheat — a millions-of-dollars savings vs. the alloy steels needing 200°F preheat. Sets up the Navy's interest in HSLA for surface ships.

Moisture, of course, is a source of hydrogen. You can tolerate 10 or 20 parts per million hydrogen in these types of steels that have very low preheat. When you go to medium preheat, which I call 100 to 300 degrees Fahrenheit, now you may have a thicker steel, or a higher carbon steel, or a little bit of alloy content — it might be an HSLA steel that's two inches thick. If it was HY80 and it's two or four inches thick you might need three or four hundred degree preheat. If it's HSLA you may only need a hundred to three hundred, or a hundred to two hundred degrees. That's why the Navy wanted to go to HSLA plate steels, and that's one of the reasons they sent me over to Japan in the mid 80s to see how the Japanese were making these steels. The Japanese were making commercial steels for shipbuilding at the time that required no preheat. They might have one-inch-thick plate that in the old days, with an alloy steel, you had to preheat to 200 degrees — now they didn't have to preheat it at all, at least during the summer in Japan. Maybe in the winter they had to get it up there, but they didn't have to preheat it. Saved them millions of dollars in shipbuilding.

Origin of the Pcm parameter — regression analysis on thousands of steels by Japanese researchers in the 1980s.

However, the second method is hydrogen control, and they don't even use the same carbon equivalent formula. Why? Because this is the type of structural steels the Japanese started developing in the 1980s, and they came up with this Pcm, which is a cracking parameter — P for parameter. Instead of silicon over six and manganese over six, it's silicon over 30 and manganese over 20. They just take thousands of steels, fit them into a regression formula, plot them up, and see which ones crack and which ones don't. And this is what they did, with lots and lots of data and computers to help them analyze it. But it's basically similar to the other carbon equivalent that we had.

Inland Steel pioneered water-spray cooling for HSLA sheet in the early 1960s but couldn't sell it to automakers. Japanese steel mills applied the technique to shipbuilding plate (sweetheart deal with shipyards). Tom's 1980s Navy-sponsored ONR trip to Japan led to $100M of Title III funding for Lukens Steel's HSLA plate line in the 1990s.

In the early 60s, some of the U.S. steel companies — not U.S. Steel, it was actually Inland Steel — started trying to make sheet steel for cars by cooling the hot-rolled steel with basically a water spray. Just like a spray from your garden hose. They put this in the steel mill and they could cool the steel down more quickly, get a finer grain size, and double the strength, and they called that a high-strength low-alloy steel. Started out as sheet metal. They spent hundreds of millions of dollars building facilities to cool this stuff and temper it and everything, and they never could convince the automotive companies to buy it at that time.