unite vs weld together

unite

verb
  • To bring together as one. 

  • To come together as one. 

noun
  • A British gold coin worth 20 shillings, first produced during the reign of King James I, and bearing a legend indicating the king's intention of uniting the kingdoms of England and Scotland. 

weld together

verb
  • To forge a social or emotional bond between people. 

  • Used other than figuratively or idiomatically: see weld, together. 

How often have the words unite and weld together occurred in a corpus of books? (source: Google Ngram Viewer )