China can possibly develop some form steam power, likely something along the lines of open turbines rather than pistons, though the latter is possible if needed to pump water from mines (as was the case in OTL Britain). Japan is also a possibility, though the stigma against merchants may limit this possibility.
Be warned however that a full-blown Euro-style Industrial Revolution is unlikely due to economic, cultural and demographic differences. There won't be major factories IMO as the population surplus will keep hand labor costs more than competitively small. Also, no real likelihood of major private exploitation but rather expect steam engines to remain in the hands of the Government bureaucracy. Gov't virtual monopolies in information (printing press) will keep designs from scattering to anyone interested like happened in Europe.
Steam China will progress slowly (as things did OTL with about every other major tech innovation they had) and methodically at the pace of government with a few specific "whiz-bang" applications like simple steam carts, clocks, rising thrones, and other toys for the Emperor being the most likely early uses. Trains may take much longer to develop than OTL Europe since alternate transportation (hundreds of peasants) will eliminate much of the demand for such. It might appear in some form (eventually) from the army when you need to move a lot of people and supplies fast across a ginormous empire, but even then technological conservativeness typically ruled military minds before the 20th century (witness how long it took to adopt automatic weapons). Asian conquests will by necessity reach an end at some point due to simply overrunning supply chains and any monetary/military reason to do so (fighting a land war in Asia is even stupider than challenging a Scicillian when death is on the line, after all). Also, why? (see "Why?" reasons for America below)
Zheng He (or more likely his ATL analog; the butterfly effect could mean he's never born or never "eunuched" into power or that the Yongle Emperor never rises to power) with steam ships (again, not a guarantee, see above for pace-of-tech changes) could theoretically travel further and heavier, but be warned against the popular myths about China's "lost" attempt at an age of discovery. (BTW Menizez's book on Zheng finding America is BS) Chinese Treasure Fleets were not out to "discover" or colonize or even make a profit, but were there to Demonstrate the Universal Power of the Celestial Throne and the inevitability and superiority of Confucian order and were (probably wisely) scrapped as wasteful practices that returned little. Maybe ATL the "Steam Ships" reach Europe and Euro clockwork toys and lens/glasswork to justify further trade travels.
Going to *America: Why? Why ride off to the edge of the world when the Middle Kingdom has everything and all else is barbarism and chaos? There's no mercantilism to drive the quest for gold. There's no rush to "save souls" since all is eternal and cyclical for ever. There's no huge reason to colonize or to grow specialty crops that almost all grow within a short boat ride away in Indochina.
If they, say, eventually travel along the Pacific Rim to find *America (which again, when things get to be more cold and inhospitable and barbaric with every Li you travel, why? Let's assume one ship blown off course and carried by the currents ala Years of Rice & Salt), there's no rush to colonize. Again, all barbarians and emptiness from all they can see. Voyages might bring back "auspicious" pieces of Giant Redwood at best unless they for some reason eventually go far enough to reach Central America or Peru and encounter something resembling "actual (Chinese) civilization". Perhaps those bloodthirsty temple builders being willing to trade valuable jade for trinkets will be worth another voyage, perhaps even (small, very limited) trade settlements along the way to support future (government-sponsored) voyages. Small populations, no real major expansions. No major OTL-style genocides because why bother? They're not there to settle. The few who flee the Chinese life maybe pass along ideas and culture to various native nations, maybe form Creole cultures. But no plantations, mass colonizations, or continent-spanning Chinese nations.
