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Heat treatment process for hull steel crankshaft

A technology for crankshafts and steel parts, which is applied in the heat treatment process of marine steel crankshafts, and can solve the problems of low fatigue strength and poor mechanical properties of cast steel crankshafts

Inactive Publication Date: 2015-08-12
GUANGXI WUZHOU YUNLONG PORT & SHIP MACHINERY MFG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] In order to solve the problems existing in the prior art, the present invention provides a heat treatment process for a marine steel crankshaft, which can solve the problems of low fatigue strength and poor mechanical properties of a cast steel crankshaft

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0014] The heat treatment process steps of the crankshaft blank cast from Φ250mm 42CrMo cast steel are:

[0015] 1) Normalizing treatment: the crankshaft blank cast from 42CrMo steel is heated to 630℃~650℃ and then kept for 1.5 hours; then the temperature is raised to 860℃ and then kept for 2.5 hours; then the temperature is raised to 900~910℃ and kept for 2.5 hours ; Then carry out air cooling to room temperature;

[0016] 2) Tempering: Place the normalized crankshaft blank in a tempering furnace, heat it to 600°C-640°C, hold it for 4 hours, and then air cool it to room temperature;

[0017] 3) Shot blasting the crankshaft blank after normalizing and tempering;

[0018] 4) Tempering:

[0019] (1) Quenching: The crankshaft blank is preheated in the furnace at 650°C for 3 hours, heated to 860°C and kept for 3 hours, then oil-cooled;

[0020] (2) Tempering after quenching: Reheat the crankshaft blank to 570°C, keep it warm for 8 to 10 hours, and then air cool it.

Embodiment 2

[0022] The heat treatment process steps of the crankshaft blank cast from Φ350mm 42CrMo cast steel are:

[0023] 1) Normalizing treatment: heat the crankshaft blank cast from 42CrMo steel to 630°C-650°C and keep it warm for 2.5 hours; then raise the temperature to 860°C and keep it warm; then increase the temperature to 900-910°C and keep it warm for 3 hours ; Then carry out air cooling to room temperature;

[0024] 2) Tempering: Place the normalized crankshaft blank in a tempering furnace, heat it to 600°C~640°C, hold it for 4.5 hours, and then air cool it to room temperature;

[0025] 3) Shot blasting the crankshaft blank after normalizing and tempering;

[0026] 4) Tempering:

[0027] (1) Quenching: The crankshaft blank is preheated in the furnace at 650°C for 4 hours, heated to 860°C and kept for 3 hours, then oil-cooled;

[0028] (2) Tempering after quenching: Reheat the crankshaft blank to 570°C, hold it for 9 hours and then air cool it.

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Abstract

The invention discloses a heat treatment process of a hull steel crankshaft, relating to the field of heat treatment. The heat treatment process comprises the following steps: normalizing: heating a 42CrMo crankshaft blank to 630-650 DEG C, wherein the heat preservation time is 0.4-0.6min / mm by diameter; heating to 860 DEG C, wherein the heat preservation time is 1-1.3min / mm by diameter; further heating to 900-910 DEG C, wherein the heat preservation time is 0.6-0.8min / mm by diameter; then, air-cooling; tempering: heating to 600-640 DEG C, wherein the heat preservation time is 1-1.2min / mm by diameter; then, air-cooling; hardening and tempering: preheating the crankshaft blank at 650 DEG C for 3-4h, heating to 860 DEG C and carrying out heat preservation for 2-4h and carrying out oil-cooling; and heating the crankshaft blank to 570 DEG C, carrying out heat preservation for 8-10h and carrying out air-cooling. The heat treatment process is capable of solving the problem that a cast steel crankshaft has relatively low fatigue strength and relatively poor mechanical property.

Description

technical field [0001] The invention relates to a metal heat treatment process, in particular to a heat treatment process for a marine steel crankshaft. Background technique [0002] With the rapid development of the shipbuilding industry, the annual demand for engines in my country is increasing. As the core component of the engine, the crankshaft plays a key role in the process of energy conversion and power output. In the marine crankshaft, the diesel engine is directly connected with the propeller shaft to transmit propulsion. In the production of marine crankshafts, the crank throws of the crankshaft are forged and cast with 45 or 42CrMo steel. The forging method requires equipment such as presses, so the machining cost is high and the manufacturing cost is high. However, due to the use of a press, the fatigue strength can be improved. Compared with the forging method, the casting method has advantages in cost and can be mass-produced, but the fatigue strength is lowe...

Claims

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Application Information

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IPC IPC(8): C21D9/30C21D8/00C21D6/00
Inventor 陈盛梅
Owner GUANGXI WUZHOU YUNLONG PORT & SHIP MACHINERY MFG
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