As it was previously said in videos on micro-upgrades, attempts to upgrade an item may be both successful and unsuccessful. The chance of upgrading an item on first stages is a lot higher than on the last ones. In case of unsuccessful micro-upgrade you can get back a half of crystals you spent on this attempt or some supplies. Let’s not forget that there is a chance of getting a double upgrade for the price of one.
Upgraded parameters don’t change the looks of your tank. If you want to take part in a battle without micro-upgrades, just create a no-supplies battle and switch on the option called Without Upgrades.

=========================================================
如图之前放出的视频所说,强化有可能会失败。强化成功率随着强化程度越高而变得越小。在强化失败的情况下,你可以拿回强化花费的水晶的一半或是一些道具。当然还有一定的机会获得双倍强化!
强化之后不会改变你的坦克的外观。如果你想参加没有强化装备的战斗,只需要创建一个没有强化的地图,类似无道具场。(以后除了拿红卡、绿卡,还会领到?T。T)
——from tankionline post bar dedicated client