Leftist takes office on Wednesday after naming finance and oil ministers.
Distributors sales also dropped in the period, industry association Inda reported.
Larger metals shipments and stronger prices will help increase Peruvian exports by nearly 10% this year, according to the country's main export association.
Marcelo Chara was dismissed from Usiminas in 2014 in a move that created a clash between Ternium and Nippon Steel.
Brazil, Argentina, Peru and Chile reported positive performances in the first four months.
But the UK-bank warns that the current bullish sentiment will be transitory, as long-term trends remain modestly bearish.