Using stainless steel slabs instead of ingots in heavy forging provides significant cost and material savings. Outokumpu showcased its 300 mm-thick stainless steel slabs at MetalForm China 2015 in Shanghai.
Cast slabs up to 300 millimeters in thickness offer numerous benefits over traditionally used ingots. Forging an ingot requires more heating, work, energy and time than forming a slab. By using slabs, the customer automatically saves resources and increases their yield by 8 to15 percent.
These are the facts presented by Outokumpu, when its 300 mm-thick slabs were showcased at the China Metal Expo, September 16–19. “Heavy manufacturing is switching toward China. We want to proactively understand the market and work with the forgers,” says
Angus Wilkinson, Outokumpu’s Product Manager.
No waste, no weakness
There are thousands of forging companies in China and the market situation is changing very quickly. “Recently we’ve come up against a lot of difficulty because the market has dropped and there is too much competition,” says
Qi Zuoyu, a Chinese forging expert, who spoke at the MetalForm event. For Outokumpu this is an opportunity to drive change, which has already taken place in the Korean market through 300-mm thick continuously cast slabs.
Continuously cast slabs are optimal for applications such as generators, power stations, and the chemical industry and they have significant advantages over the use of ingots. The most obvious is that with an ingot you waste at least 20 percent of the metal as you have to cut off the top, due to a defect known as pipe, which makes this layer as well as the bottom layer porous.
Not so obvious are the internal properties of stainless steel, which have columnar grains in the middle, which causes a plane of weakness. “With continuous casting, you have an inclusion flotation stage known as the tundish, which reduces the number of inclusions. So the entire length of slab is perfectly clean and sound,” explains
John Beeley, Outokumpu General Manager for Business Line SMACC.
Factor for the quality
Outokumpu’s impending task is to find the right forgers and to show them that by using the slabs, they can improve their competitiveness. Qi concurs: “In the forging industry, we say the quality depends 70 percent on the raw material and 30 percent on how we forge it. This is a good opportunity, as all forging factories meet a challenge to increase quality and reduce costs. They have to transform from low quality low efficiency to a higher level.”
Usually the maximum thickness for slabs is 240 mm, which for some applications is not sufficient as a substitute for ingots. Outokumpu is the only European producer able to produce the 300 mm slabs. Outokumpu is able to meet the needs of Chinese forgers, with both capabilities and high quality available.