There are different journals of differing levels of importance in for different subfields of history. Most of them are on JSTOR or other similar aggregators. There is no preprint tradition in history. In general, history publications take MUCH longer to produce and go to press than in the sciences, and there is a lot less pressure to try and "keep up on the literature" other than that which pertains to what you are directly working on. In many ways books are more important than articles for historians, in terms of learning about the works of others who are doing work on topics other than the one you yourself directly research.