Many Japanese steel mills are already experiencing slack capacity, enabling them to ramp up output to meet any increase in domestic demand, dampening imports from China or elsewhere.
"There is plenty of spare capacity in Japan for long products and any increased demand from reconstruction would essentially come from the Japanese themselves," said Peter Hickson, a global commodities strategist at UBS.
"Our observations are that the long products segment in Japan is running at about 60 percent utilisation, so there is plenty of capacity there. I'd say there'd be fairly limited opportunities for Chinese steelmakers."
Japanese steelmakers escaped largely unscathed from Friday's 8.9-magnitude earthquake that struck across its north eastern coastline which later generated a 10-metre high tsunami wave that wiped off whole villages and towns.
Even if there was a window of opportunity for higher imports of long products into Japan, Chinese steel mills would still face quality issues.
"Chinese steel mills are unlikely to see a big boost in exports to Japan as steel products made in China, especially long products, are hard to meet Japan's earthquake-resistant standard," said a senior steel exporter in Beijing.
However, analysts said there would be room for Chinese mills to sell more high-end flat products into the island nation, as Japan's supply of such products, commonly used in the automobile industry, has become increasingly stretched over the past few quarters.
As Japan's steelmaking giants Nippon Steel and JFE Steel face reduced output in the coming weeks due to blackouts and ship less steel abroad when it embarks on reconstruction in the coming months, its steel exports may fall and pave the way for Chinese mills to fill the gap, said Henry Liu, Mirae Asset's regional head of commodities research.
"It would help Chinese mills reduce their bulging stockpiles and that's a big plus, although competition from South Korea would be stiff," he said.
Shares in China's steel exporters were mostly up on Monday, with Baosteel gaining over 2.1 percent, Angang up 2.6 percent and Wuhan Steel up 2 percent, outperforming the broader index's 0.13 percent gain.
WILD CARDS
UBS' Hickson said Chinese steel mills could see big gains if Japanese authorities decide to reinforce key infrastructure against future tsunamis.
"Most of the destruction in Japan was caused by the tsunami and not the quake. So if the government decides to protect its ports, coasts and nuclear power plants, then that will lead to higher-than-expected steel demand," he said.
Still, Mirae Asset's Liu cautioned against being overly optimistic on Japan's commodities demand from its rebuilding efforts, drawing lessons learnt from China's reconstruction after the devastating Sichuan earthquake in 2008.
"The rebuilding in Sichuan was far less than what people had expected," he said.
Japan accounts for 8 percent of global crude steel output, 7 percent of global hot-duct output and 6 percent of global hot-rolled consumption.
China owns annual crude steel capacity of more than 750 million tonnes and is likely to boost capacity to 800 million tonnes this year.