Fluid end with transition surface geometry

A fluid end, comprising:

• a first bore comprising a cylindrical portion;
• and
• a second bore extending through the fluid end and intersecting the first bore at a crossbore, wherein the second bore comprises a first tapered portion increasing a cross-sectional area of the second bore along the first tapered portion toward the crossbore, the second bore comprises a second tapered portion reducing the cross-sectional area of the second bore along the second tapered portion toward the crossbore, and the second tapered portion interfaces with the cylindrical portion of the first bore.

A method for manufacturing a fluid end, the method comprising:

• forming a first bore of the fluid end, wherein the first bore comprises a main cylindrical portion;
• and
• forming a second bore of the fluid end to intersect with the first bore at a crossbore of the fluid end, wherein forming the second bore comprises forming a tapered portion and an additional tapered portion of the second bore, the tapered portion reducing a cross-sectional area of the second bore along the tapered portion toward the crossbore, the tapered portion and the main cylindrical portion cooperatively define a peak that extends inwardly to the crossbore, and the additional tapered portion increases the cross-sectional area of the second bore along the additional tapered portion toward the tapered portion and the crossbore of the fluid end.