Steel and manufacturing method for Ca microalloying free-cutting high-strength expansion-breaking connecting rod

Abstract

The invention relates to steel for a Ca microalloying free-cutting high-strength expansion-breaking connecting rod. The steel is prepared from, by mass percent, 0.25%-0.60% of C, 0.10%-1.20% of Si, 0.40%-1.50% of Mn, 0.05%-0.50% of Cr, 0.02%-0.15% of S, 0.02%-0.15% of P, 0.03%-0.55% of V, 0.0005%-0.0080% of Ca, 0.002%-0.035% of N, 0.002%-0.080% of Al, not larger than 0.02% of Ti and the balance Fe and inevitable impurity elements. The steel is subjected to smelting, continuous casting, heating, hot rolling and cooling, and the structure characteristic is uniform ferrite and pearlite. According to the steel, key elements in the steel are optimized, Ca microalloying is especially adopted, and the steel for the expansion-breaking connecting rod with high strength, good cutting machinability, good expansion-breaking performance and excellent comprehensive performance is obtained, and the design requirements for engine light weight, economical efficiency and driving comfort are met.

Description

technical field [0001] The invention relates to a Ca microalloyed steel material and a manufacturing method thereof, in particular to a free-cutting high-strength bursting connecting rod steel and a manufacturing method thereof. Background technique [0002] With the rapid development of the transportation industry. The proportion of high-strength, easy-to-cut expandable connecting rod steel used in automobile, ship and other vehicle engines continues to increase. Energy pressure requires higher strength in engine connecting rods for light weight and good cutting performance. The driving comfort requires good assembly performance of the engine connecting rod, and the expansion connecting rod has better assembly performance than the cut-off connecting rod. In order to meet the above requirements, inventing a Ca microalloyed free-cutting high-strength bursting connecting rod has broad market prospects. [0003] Application No. 201510612936.4 discloses a free-cutting medium-...

AI Technical Summary

Problems solved by technology

The machinability of this steel has been improved, but it is still difficult to solve the problem of machinability and cracking, and in order to improve the machinability of this steel, the amount of alloy addition is appropriately reduced, resulting in a decrease in material strength

And this steel type adds a relatively high content of Ti element, so that a large amount of harmful Ti-containing inclusions are formed in the steel, and the fatigue performance of the material is significantly reduced.

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