"使成可塑体" can be translated as "to render (something) plastic" or "to make (something) malleable/pliable" in English, depending on the specific context.
If you're referring to the process of making a material or substance capable of being shaped or molded, "to render it plastic" or "to make it malleable/pliable" would be appropriate.
For a more technical or scientific context, you might use terms like "to plasticize" (though this is more commonly used in the context of polymers and plastics) or describe the specific changes in properties that make the substance plastic.
In a general or less technical sense, "to make it malleable" or "to make it workable" (in the sense of being able to be shaped or formed) would also convey the idea.
Example sentence:
"The heat treatment process renders the metal plastic, allowing it to be easily shaped into the desired form."
（热处理工艺使金属具有可塑性，从而可以轻松地将其塑造成所需的形状。）