CN102517500A - Rolling process for producing 35CrMo alloy cold forging steel through adopting small billets - Google Patents

Abstract

The invention which relates to a rolling process for producing 35CrMo alloy cold forging steel through adopting small billets belongs to the technical field of molding. The rolling process comprises the following steps: 1, heating the billets to 1030-1080DEG C, and maintaining the temperature for 1.5-2.5h; 2, hot-rolling after the temperature maintenance, and controlling the bloom rolling temperature at 950-1000DEG C, the finish rolling inlet temperature at 880-920DEG C, the reducing and sizing inlet temperature at 870-920DEG C and the spinning temperature at 850-900DEG C; and 3, cooling in a Stelmor line cooling mode: delay-cooling. Phi8-12mm wire rods produced through rolling have the following structure and mechanical properties: the tissue comprises ferrite and pearlite, the tensile strength is 660-735Mpa, the reduction of area is 48-64%, and the half radius hardness (HRB) of a cross section is 82-95.

Description

A kind of rolling method that adopts little square billet to produce 35CrMo alloy cold heading steel

Technical field

The invention belongs to field shaping technique, relate to a kind of hot-rolling method that adopts little square billet to produce 35CrMo alloy The cold heading steel.

Background technology

35CrMo alloy cold heading steel is mainly as standardized component and the important structure part that is applied to work under the high loading such as 10.9～12.9 grades of socket head cap screws of manufacturing HS; Like the driving member of vehicle and mover, the transmission shaft of the rotor of turbo-generator, main shaft, heavy lift etc.

Produce the 35CrMo steel grade except that requiring to have the good slab quality, because of containing Cr, Mo alloying element, and the comprehensive action of Cr and Mo can improve the stability of supercooled austenite, significantly to prevent thickization of austenite crystal in the steel.Therefore, when rolling 35CrMo alloy cold heading steel, controlled rolling and controlled cooling (TMCP) technology is particularly crucial.The present invention is intended to adopt the little square billet of 150mm section to produce 35CrMo alloy cold heading steel, does not see relevant report.

Summary of the invention

The objective of the invention is to disclose a kind of method of producing 35CrMo alloy cold heading steel with the little billet rolling of 150mm section.

Technical solution:, adopt little square billet rolling 35CrMo alloy cold heading steel on high-speed rod-rolling mill of 150mm section through to the appropriate design of 35CrMo alloy cold heading steel composition and the control of TMCP technology.

Technical scheme of the present invention is achieved in that

35CrMo alloy cold heading steel provided by the invention, its chemical ingredients (mass percent) is: C:0.32～0.40%, Si:0.15～0.35%; Mn:0.6～0.90%; P :≤0.035%, S :≤0.035%, Cr :≤0.8～1.1%; Mo :≤0.15～0.25%, all the other are matrix Fe and the trace element that can't detect.

The present invention adopts the little square billet of the 150mm section with above-mentioned chemical ingredients on high-speed rod-rolling mill, to produce 35CrMo alloy The cold heading steel; Carry out temperature control in the operation of rolling; Take delayed quench after rolling; Accomplish phase transformation under the cooling rate slowly in the stay-warm case on the stelmor roller-way, obtain ferritic and add pearlitic structure.Concrete rolling method carries out according to the following steps:

(1) steel billet is heated to 1030～1080 ℃, is incubated 1.5～2.5 hours;

(2) carry out hot rolling after the insulation, the control start rolling temperature is 950～1000 ℃; The finish rolling temperature in is 880～920 ℃; Subtract 870～920 ℃ of sizing temperature ins; 850～900 ℃ of laying temperatures;

(3) the Stevr line type of cooling of rubbing: delayed quench.

Description of drawings

Fig. 1 organizes photo for φ 8mm wire rod;

Fig. 2 organizes photo for φ 10mm wire rod;

Fig. 3 organizes photo for φ 12mm wire rod.

Embodiment

Below in conjunction with embodiment the present invention is further described.

Embodiment 1

Select little square billet Rolling Production φ 8～φ 12mm wire rod on high-speed rod-rolling mill of 150mm section, its chemical Composition Control such as table 1, and be rolled by following rolling method:

(1) steel billet is heated to 1050 ℃, is incubated 1.5 hours;

(2) carry out hot rolling after the insulation, the control start rolling temperature is 980 ℃; The finish rolling temperature in is 900 ℃; Subtract 880 ℃ of sizing temperature ins; 860 ℃ of laying temperatures; Finish to gauge speed: φ 8mm is 90m/s, and φ 10mm is 60m/s, and φ 12mm is 40m/s;

(3) the Stevr line type of cooling of rubbing: delayed quench.

Wire rod is organized and mechanical properties test, and φ 8mm wire rod organizes photo to see Fig. 1, and its tissue is mainly ferritic and adds perlite, and wherein 1/2 radius has the martensite less than 5% to the center, and it is 11 grades that 1/2 radius is organized grain fineness number.The photo of organizing of φ 10mm, φ 12mm wire rod is seen Fig. 2, Fig. 3, and its tissue is ferritic and adds perlite, and 1/2 radius organizes grain fineness number to be respectively 10.5,10 grades.Wire rod hot rolling attitude mechanical property detected value is seen table 2, and the tissue of wire rod φ 8mm～φ 12mm and mechanical property satisfy the requirement of 35CrMo steel in the relevant criterion.

Table 1 35CrMo alloy cold heading steel chemical Composition Control (mass percent %)

C	Si	Mn	P	S	Cr	Mo
							0.33	0.30	0.80	0.02	0.009	0.90	0.15

The mechanical property of table 2 35CrMo alloy cold heading steel gren rod

Claims (2)

1. rolling method that adopts little square billet to produce 35CrMo alloy cold heading steel, the chemical Composition Control that it is characterized in that steel be at (mass percent): C:0.32～0.40%, Si:0.15～0.35%; Mn:0.6～0.90%; P :≤0.035%, S :≤0.035%, Cr :≤0.8～1.1%; Mo :≤0.15～0.25%, all the other are matrix Fe and the trace element that can't detect.

2. characteristic a kind of adopts little square billet to produce the rolling method of 35CrMo alloy cold heading steel according to claim 1, it is characterized in that:

(1) steel billet is heated to 1030～1080 ℃, is incubated 1.5～2.5 hours;

(2) carry out hot rolling after the insulation, the control start rolling temperature is 950～1000 ℃; The finish rolling temperature in is 880～920 ℃; Subtract 870～920 ℃ of sizing temperature ins; 850～900 ℃ of laying temperatures;

(3) the Stevr line type of cooling of rubbing: delayed quench.

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