30CMnMo numerical simulation of quenching seamless tube

Based on the blood physical characteristics of the quenching medium and solid surface, the finite element software was used to quantitatively simulate the quenching process of the 30CMnMo steel seamless pipe—analyzed the quenching temperature and residual stress—the effect of residual stress along the cylinder was realized during the process. The stress simulation of the outer edge is consistent with the production data, which is of great significance for the establishment of the thermal group and the prediction of product quality and life.

The heat treatment process has attracted more and more attention in improving the mechanical properties of seamless steel pipes. Computer simulation technology has been successfully applied to the heat treatment of seamless steel pipes. The boundary conditions of the quenching process of seamless steel pipes are highly nonlinear, and in the quenching process The temperature field and stress interact with each other, so it is difficult to quantitatively study the temperature field and stress field at the same time in the actual quenching process - the actual production process of internal spraying and external spraying has been realistically simulated by using the finite element method, and the relationship between the quenching temperature field and stress field obtained from the simulation The relationship between them has important guiding significance for further exploring the quenching process of seamless steel pipes.

1 Establishment of finite element calculation model
In this paper, calculations are carried out for a high-strength oil well seamless steel pipe. 19 mm in a factory, and the relationship between the temperature field and the stress field along the thickness of the steel pipe wall during the quenching process is mainly studied .
1.1 Geometric model and network division
A factory manufactures Pl ]. The oil casing is made of 30CMnMo steel, and the quenching temperature is 900°C. In order to ensure the quenching quality, the internal spray and external spray cooling methods are adopted . Axial geometric symmetry of oil casing . The cooling water flow velocity in the steel pipe is greater than 13 m/s and the rotational speed of the steel pipe is greater than 60 r/min. If the above conditions are met, the cooling process of the entire steel pipe is considered to be carried out at the same time. The process parameters are: the pressure claw exerts a pressure of 4 MPa on the steel pipe Tighten the steel pipe, the rotating speed of the supporting wheel is 70~75 r/nin , the amount of water sprayed outside during the quenching process is 3 66 m 3 /mn • m, and the amount of water sprayed inside is 1 1 . . m 3 /h ( the flow velocity inside the steel pipe is much greater than 13 m /) • Therefore, the quenching process can be regarded as a plane strain problem , Take the axial cross-section of the casing for modeling

12Physical parameters of oil casing
During the quenching process, the steel pipe has a large temperature span and a large degree of structural change, so the thermophysical parameters are regarded as a function of temperature. The chemical composition of 30CMnMo steel is shown in Table 1. The physical parameters are shown in Table 2 .

Tab le 1 The ch on ical com position of 30c iM nM o steel

C	Si	Mn	P	S	cr	Mo	Al
0. 26-0．32	0. 20-0．33	0. 85 ~1 00	0.020	0.015	0.90-1.05	0.35~0.45	0.010-0.030

2 Quenching medium characteristics exhibits different physical states when the superheat is less than 1000°C , which can be divided into three stages : pool boiling , nucleate boiling , and film boiling [] .

Table 1 Physical param eters of 30c M nM o steel

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