The present invention provides a
petroleum casing
pipe with high strength and high
toughness, wherein the weight of the component element of the casing
pipe steel is characterized proportionally. The invention also provides a preparing method for preparing the
petroleum casing
pipe with high strength and high
toughness, wherein the method comprises the following steps: 1.
smelting the ingredients and
casting the tube blank; 2.
punching and tandem rolling of the
steel tube; and 3.
heat treating. The invention has the following beneficial effects: the performance of the
petroleum casing pipe obtained by the method is the performance of the steel with lower content of
alloy and the cost is low; a low carbon content is adopted so that the
lath martensite tissue is obtained after heat treatment, the high
toughness is provided after
tempering and a
delayed fracture resistance is provided; the complex micro-alloying
processing techniques of V, Nb, Ti, B, etc. are adopted for strengthening the matrix, strengthening the grain-
boundary strength, increasing the
tempering resistance, reducing the content of
manganese element, reducing the content of the
impurity elements and improving the shape of the inclusion. The rolling ratio is optimized so that the aeolotropism of the material is remarkably reduced and the
horizontal and vertical impact toughness of the material is larger than 0.8. The casing pipe of the invention far exceeds the prior highest steel grade requirement of the API standard.