Non-quenched and tempered steel containing Ti and N and applied to automobile engine crankshaft and preparation method

A technology of automobile engine and non-quenched and tempered steel, applied in the direction of crankshaft, etc., can solve the problems of increasing production cost, and achieve the effect of reducing machining cost and production cost

Inactive Publication Date: 2018-01-16
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] By reducing the carbon content and increasing the manganese content, the toughness of

Method used

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  • Non-quenched and tempered steel containing Ti and N and applied to automobile engine crankshaft and preparation method
  • Non-quenched and tempered steel containing Ti and N and applied to automobile engine crankshaft and preparation method
  • Non-quenched and tempered steel containing Ti and N and applied to automobile engine crankshaft and preparation method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 4

[0024] In Example 4, Ti and N are not added to the chemical composition. The austenite grain size of the rolled product is 6.5-8.0, with a range of 1.5; the structure at the center and 1 / 2 radius is relatively coarse, and the uniformity of the structure is poor. Room temperature impact energy KU of the crankshaft 2 The average value is only 8J, and the cross-section hardness of the output end is too high, ranging from 262 to 286HB.

Embodiment 5

[0025] In Example 5, the Mn and Cr in the chemical composition exceeded the upper limit required by the composition. The austenite grain size of the rolled material is 8.0-8.5, the extreme difference is 0.5, and the structure is fine and uniform. But the room temperature impact energy KU of the crankshaft 2 The average value is only 14J, and the cross-section hardness of the output end is too high, ranging from 261 to 276HB.

[0026] The chemical composition (mass percentage) that the embodiment of table 1 adopts

[0027]

[0028] Table 2 embodiment rolling material organization statistical result

[0029]

[0030] Table 3 embodiment crankshaft performance test result

[0031]

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PUM

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Abstract

The invention belongs to the field of metal materials, and relates to non-quenched and tempered steel containing Ti and N and applied to an automobile engine crankshaft. The non-quenched and temperedsteel comprises chemical components in percentage by mass as follows: 0.44%-0.48% of C, 0.25%-0.45% of Si, 0.82%-0.92% of Mn, 0.12%-0.21% of Cr, 0.07%-0.10% of V, 0.02%-0.03% of Ti, 0.010%-0.020% of N, smaller than or equal to 0.025% of P, 0.040%-0.060% of S and the balance of Fe and normal impurities. The microscopic structure of a large rolled bar (with diameter being 110 mm) containing the components is pearlite+ferrite, and the structure of the large rolled bar is thinner and has good uniformity; austenite grain size in the position of 1/2 radius of the large rolled bar can reach level 8.0, and core-surface grain size range can be as low as level 0.5. The crankshaft is made of the large rolled bar as a raw material through die forging, and the microscopic structure of the crankshaft ispearlite+grain boundary ferrite+intragranular ferrite; yield strength in the position of 1/2 radius of a main journal of the crankshaft can reach 500 MPa or higher, tensile strength can reach 800 MPaor higher, and room-temperature impact energy KU2 can reach 20 J or higher; hardness of a cross section of an output end of the crankshaft is 240-260 HB, which is suitable for drilling operation, andmachining cost can be reduced. Therefore, requirements for structure uniformity of the large rolled bar and comprehensive mechanical properties of the crankshaft can be met.

Description

technical field [0001] The invention belongs to the field of metal materials, and is a medium-carbon pearlite + ferrite non-quenched and tempered steel, and specifically relates to a component design that meets the requirements of the microstructure and comprehensive performance requirements of the non-quenched and tempered steel large bar for automobile engine crankshafts. Background technique [0002] Non-quenched and tempered steel is to add a certain amount of microalloy elements on the basis of medium and high carbon steel, through controlled rolling (forging) and controlled cooling, so that it can be achieved without quenching + tempering process after rolling (forging). A steel grade with comparable mechanical properties to quenched and tempered steel. Compared with quenched and tempered steel, non-quenched and tempered steel has the advantages of energy saving and emission reduction, simple process, short production cycle and low cost. With the rapid increase of my ...

Claims

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Application Information

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IPC IPC(8): C22C38/28C22C38/24C22C38/60C22C38/04C22C38/02C21D8/06F16C3/06
Inventor 刘雅政赵帆蒋波张朝磊刘广磊吴萌周宁波纪岩陈列
Owner UNIV OF SCI & TECH BEIJING
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