CN104531962A - Welding repair vacuum heat treatment method after martensitic stainless steel casting is machined in finish mode - Google Patents

Abstract

The invention provides a welding repair vacuum heat treatment method after martensitic stainless steel casting is machined in a finish mode. The method comprises the following steps that the casting is cleaned in advance, and Na2CO3 and deionized water are adopted for carrying out degreasing; gas is removed in a vacuum mode, the casting treated through degreasing is placed into a vacuum furnace after being dried in air or dried through wiping, gas exhausting is stopped after being carried out for one hour with the vacuum degree maintained at 1 Pa within the range of below 100 DEG C, and argon is injected until furnace pressure is 0.025-0.05 MPa while heating is carried out with the heating rate of 30-55 DEG C per hour; vacuum tempering is carried out, within the vacuum degree range of 0.025-0.05 MPa, after heat is preserved for 3-3.5 hours at the temperature of 600 DEG C, high-purity argon of 10 L/min is injected into a furnace, vacuum gas exhausting is carried out for cooling, the cooling rate is controlled to be smaller than or equal to 55 DEG C per hour, and the casting is cooled to 60-70 DEG C and discharged out of the furnace. The tensile strength of the obtained martensitic stainless steel casting is larger than 780 MPa, and the percentage elongation after fracture is larger than 18%.

Description

Soldering vacuum heat-treating method after the precision work of Martensite Stainless Steel foundry goods

Technical field

The invention belongs to technical field of metal, the vacuum destressing heat treatment method particularly after the precision work of a kind of Z5CND13-04 Martensite Stainless Steel foundry goods after rewelding.

Background technology

Z5CND13-04 belongs to high strength martensitic stainless steel in French RCC-M standard, vapor sensitivity is high, very easily produce the defects such as pore, owing to significantly improving for both requirements comparatively rear of Nuclear power plants mechanical property, composition range control overflow is more accurate, is widely used in the fields such as space flight and aviation, nuclear power, motor-car.

Vacuum heat treatment has non-oxidation, without decarburization, is out of shape little, smooth finish advantages of higher, is a kind of metal fever processing mode that heat treatment industry is pursued for a long time.Vacuum heat treatment has been widely used in mould Heat Treatment Of Steel, but is seldom applied in the thermal treatment after high-strength stainless steel casting precision work soldering.

Domesticly at present mainly in postweld heat treatment adopt traditional normative heat treatment mode, there is oxidation, smooth finish is poor, dimensional precision is not high shortcoming, dimensional precision and the smoothness requirements of the destressing of intensely processed products postwelding cannot be met.

Summary of the invention

The present invention causes the problem of scrapping in order to solve foundry goods under conventional conditions because postweld heat treatment produces oxidation, distortion etc., thus the vacuum heat-treating method of a kind of Z5CND13-04 Martensite Stainless Steel foundry goods postwelding after precision work is provided, the method can meet the uniformity of hardness of soldering after the precision work of high strength martensitic stainless cast steel part, intensity and dimensional precision, surface smoothness.

For solving the problems of the technologies described above, the present invention takes following technical scheme:

Soldering vacuum heat-treating method after the precision work of Z5CND13-04 Martensite Stainless Steel foundry goods, comprises the steps:

The first step: the pre-washing of foundry goods, adopts Na ₂cO ₃+ deionized water carries out degrease process;

Second step: vacuum degassing, by air-dry for the foundry goods after degrease process or put into vacuum oven after drying, maintaining 1Pa vacuum tightness in less than 100 DEG C scopes bleeds after 1h, stops bleeding, then to be filled with argon gas to furnace pressure 0.025 ~ 0.05MPa while the heating of the temperature rise rate of 30 ~ 55 DEG C/h;

3rd step: vacuum tempering, in 0.025 ~ 0.05MPa vacuum ranges, 600 DEG C of insulations after 3-3.5 hour, then are filled with 10L/min high purity argon+vacuum suction and cool in stove, and controlled cooling model speed≤55 DEG C/h is cooled to 60 ~ 70 DEG C and comes out of the stove.

The beneficial effect of employing technique scheme is:

The tensile strength of the Martensite Stainless Steel foundry goods that the present invention obtains is at more than 780MPa, elongation after fracture more than 18%, 0 DEG C is impacted more than 40J, in the postweld heat treatment of high strength martensitic stainless cast steel part, adopt vacuum tempering thermal treatment process, heat with certain rate of heating in condition of high vacuum degree and be incubated, then in stove, be filled with highly purified argon gas cool, ensure that the comprehensive mechanical property of foundry goods, there is following characteristics:

1. Na ₂cO ₃+ deionized water carries out degrease process, air-dry or put into vacuum oven after drying, and maintains about 1Pa vacuum tightness and bleeds after 1h, effectively remove moisture, grease etc., prevent foundry goods from producing oxidation stain in less than 100 DEG C scopes.

2. in heat-processed, there is highly purified argon gas to protect, without the generation of thermal treatment coloring phenomenon.

3. vacuum cooling is filled with 10L/min high purity argon+vacuum suction and cools, and controlled cooling model speed≤55 DEG C/h, ensures stability and the mechanical property of product size.

Accompanying drawing explanation

Fig. 1 is soldering vacuum heat-treating method after Martensite Stainless Steel foundry goods of the present invention precision work

Process curve figure.

Fig. 2 is Martensite Stainless Steel volute casting structure figure of the present invention.

Embodiment

The following examples can make the present invention of those skilled in the art comprehend, but do not limit the present invention in any way.

For Z5CND13-04 high strength martensitic stainless steel volute foundry goods weld vacuum destressing thermal treatment, vacuum tempering is at employing Na ₂cO ₃+ deionized water carries out degrease process, vacuum oven is put into after drying, maintaining about 1Pa vacuum tightness in less than 100 DEG C scopes bleeds after 1h, stopping is bled, 0.025 ~ 0.05MPa is maintained to furnace pressure again to be filled with argon gas while the heating of the temperature rise rate of 30 ~ 55 DEG C/h, vacuum tempering vacuum range is in 0.025 ~ 0.05MPa vacuum tightness, 600 DEG C of insulations 3 are little after 3 hours 15 minutes, in stove, be filled with 10L/min high purity argon+vacuum suction again cool, controlled cooling model speed≤55 DEG C/h is cooled to 60 ~ 70 DEG C and comes out of the stove.

It is 780 ~ 810MPa that the high strength martensitic stainless cast steel part adopting present method tempering to obtain manages coupon through the tensile strength of Physico-chemical tests with furnace treatment, elongation after fracture more than 18%, 0 DEG C is impacted more than 40J, body soldering position hardness and mother metal basically identical, through scribing inspection, without obviously distortion, outward appearance non-oxidation, ensure that the comprehensive mechanical property of foundry goods.

Below suitably illustrate this invention, but the present invention is not limited thereto, various forms of heat treating method can be specialized within the technology item category not going out this invention.

Claims (1)

1. soldering vacuum heat-treating method after the precision work of Martensite Stainless Steel foundry goods, it is characterized in that, the method comprises the steps:

The first step: the pre-washing of foundry goods, adopts Na ₂cO ₃+ deionized water carries out degrease process;

Second step: vacuum degassing, by air-dry for the foundry goods after degrease process or put into vacuum oven after drying, maintaining 1Pa vacuum tightness in less than 100 DEG C scopes bleeds after 1h, stops bleeding, then to be filled with argon gas to furnace pressure 0.025 ~ 0.05MPa while the heating of the temperature rise rate of 30 ~ 55 DEG C/h;

3rd step: vacuum tempering, in 0.025 ~ 0.05MPa vacuum ranges, 600 DEG C of insulations after 3-3.5 hour, then are filled with 10L/min high purity argon+vacuum suction and cool in stove, and controlled cooling model speed≤55 DEG C/h is cooled to 60 ~ 70 DEG C and comes out of the stove.