CN-116337924-B - Vickers hardness assessment method and system for marine steel welded joint

CN116337924BCN 116337924 BCN116337924 BCN 116337924BCN-116337924-B

Abstract

The invention belongs to the technical field of welding hardness, and particularly provides a Vickers hardness evaluation method and system for a welding joint of marine steel, wherein the method comprises the steps of obtaining a thermal cycle curve of the welding joint of the marine steel, and discretizing the thermal cycle curve to obtain a temperature curve; the method comprises the steps of inputting chemical components related to marine steel, evaluating key temperatures of metal solid phase transformation, calculating percentages of microstructure components capable of participating in the metal solid phase transformation, calculating transient microstructure changes in different temperature change intervals from heating to cooling in the whole welding process according to time steps of discretization treatment, so as to obtain final microstructure component proportions, and carrying out weighted summation on different microstructures to obtain final Vickers hardness. The method can accurately calculate the Vickers hardness value of the steel welding joint for the ship without damaging the welding joint, has low cost and convenience, and is suitable for popularization and application.

Inventors

WANG JIANGCHAO
JIA MINGYUAN
ZHANG QINGYA
LIU JINGXI

Assignees

华中科技大学

Dates

Publication Date: 20260508
Application Date: 20230313

Claims (8)

1. The Vickers hardness evaluation method of the steel welded joint for the ship is characterized by comprising the following steps of: S1, obtaining a thermal cycle curve of a welded joint of marine steel, and discretizing the thermal cycle curve to obtain a temperature curve; s2, inputting chemical components related to the marine steel, and evaluating the key temperature of the solid-state phase transition of the metal; s3, calculating the percentage of each microstructure component currently participating in the solid-state transformation of the metal, specifically, calculating the proportion of ferrite, pearlite and residual austenite currently participating in the solid-state transformation of the metal; S4, calculating transient microstructure changes in different temperature change intervals from temperature rise to temperature reduction in the whole welding process according to the time step of discretization in the step S1 so as to obtain a final microstructure component proportion, and carrying out weighted summation calculation on different microstructures so as to obtain final Vickers hardness; Specifically, taking the average value of the maximum value and the minimum value of the temperature curve as the loading value of the temperature curve, wherein the loading time is the time step, and calculating the transient microstructure proportion of different temperature change intervals; the temperature change interval specifically comprises when the temperature is lower than the austenite transformation temperature, when the temperature is between the austenite transformation temperature and the complete austenitization temperature, when the temperature is higher than the complete austenitization temperature, when the cooled austenite is transformed into ferrite, when the cooled austenite is transformed into pearlite, when the cooled austenite is transformed into bainite, when the cooled austenite is transformed into martensite, and when the temperature is reduced to room temperature; S5, regarding the thermal cycle curve of the multi-layer multi-pass welding, the decomposed and transformed bainite and martensite have irreversibility, the contents of the residual austenite, ferrite and pearlite are required to be used as new microstructure initial conditions, and the transformation of the austenite in the heating process, the growth of the crystal grains and the calculation and analysis of the decomposition and transformation of the austenite in the cooling process are carried out again; specifically, in the first welding thermal cycle, the microstructure content participating in austenite transformation=ferrite content+pearlite content; At the subsequent welding thermal cycle, the microstructure content participating in the austenite transformation=1-bainite content-martensite content.
2. The method for evaluating the vickers hardness of a steel welded joint for a vessel according to claim 1, wherein S1 specifically comprises: Setting a time step, and dispersing a continuous welding thermal cycle curve into a plurality of straight line segments with increased temperature or reduced temperature.
3. The method of evaluating the vickers hardness of a steel welded joint for a vessel according to claim 1, wherein the microstructure includes austenite, complete austenite, pearlite, ferrite, bainite, and martensite.
4. The method for evaluating the vickers hardness of a steel welded joint for a ship according to claim 1, wherein S2 specifically comprises calculating an austenite transformation temperature, a complete austenitization temperature, a metal melting temperature during heating, and a transformation temperature at which austenite is decomposed into pearlite, ferrite, bainite, and martensite during cooling, according to chemical components of the steel for a ship.
5. The method for evaluating the Vickers hardness of a steel welded joint for a ship according to claim 1, wherein the step S4 further comprises the steps of spot-welding a high-temperature platinum-rhodium alloy temperature sensor at a temperature measuring position to obtain a Vickers hardness detection value in real time, and comparing the detection value with a summation calculation value to analyze and verify the calculation value.
6. A system for evaluating the vickers hardness of a steel welded joint for a ship, characterized in that it is used to implement a method for evaluating the vickers hardness of a steel welded joint for a ship according to any one of claims 1 to 5, comprising: The thermal cycle curve discretization module is used for acquiring a thermal cycle curve of a welding joint of the marine steel and discretizing the thermal cycle curve to obtain a temperature curve; the key temperature evaluation module is used for inputting chemical components related to the marine steel and evaluating the key temperature of the solid-state phase transition of the metal; the current microstructure component calculation module is used for calculating the percentage of each microstructure component currently participating in the solid-state phase transformation of the metal; The Vickers hardness evaluation module is used for calculating transient microstructure changes in different temperature change intervals from temperature rise to temperature reduction in the whole welding process according to the time step of discretization treatment so as to obtain the final microstructure component proportion, and carrying out weighted summation calculation on different microstructures to obtain the final Vickers hardness.
7. An electronic device comprising a memory, a processor for implementing the steps of the vickers hardness assessment method of a steel marine weld joint according to any one of claims 1-5 when executing a computer management type program stored in the memory.
8. A computer-readable storage medium, characterized in that a computer-management-class program is stored thereon, which, when being executed by a processor, implements the steps of the vickers hardness assessment method of a steel welded joint for a ship as claimed in any one of claims 1-5.

Description

Vickers hardness assessment method and system for marine steel welded joint Technical Field The invention relates to the technical field of welding hardness, in particular to a Vickers hardness evaluation method and system for a ship steel welding joint. Background The marine common steel (Q235, Q345, etc.) and the high-strength steel (EH 46, EH56, etc.) plates are generally subjected to carbon dioxide gas shielded welding to complete assembly and connection of sheet bodies, components, etc., and meanwhile, the marine steel thick plate is subjected to multi-layer multi-pass welding to complete groove filling through multi-pass welding deposition. The Vickers hardness of the welded joint is seriously affected by the complex thermal cycle process of welding heating and cooling, and the ductility and toughness of the steel are reduced along with the increase of the hardness, the comprehensive mechanical property is reduced, and the fracture resistance is weakened. Vickers hardness was proposed by vickers corporation (VICKERS LTD) in 1921 by british, smith (Robert l. Smith) and serderland (George e.sandland), and is a standard for indicating material hardness. Specifically, the vickers hardness refers to that a diamond regular pyramid pressure head with an included angle of 136 degrees between opposite surfaces is pressed into the surface of a tested sample under the action of a specified load F, the load is removed after the fixed time is kept, the diagonal length d of the indentation is measured, the surface area of the indentation is calculated, and finally the average pressure on the surface area of the indentation is calculated, namely the vickers hardness value of the metal is expressed by a symbol HV. The calculation formula of the Vickers hardness of the material is as follows: F=load (newton force) S=indentation surface area (square millimeter) Α=the angle between the opposed faces of the ram=136° D = average indentation diagonal length (millimeters). A first test method standard GB 2654-1981 for the Vickers hardness of metal welding seams, namely the welding joint and surfacing metal hardness test method, is published in 1981, and a maximum hardness test method for a welding heat affected zone of a welding performance test is published in 1984 by equivalently adopting Japanese JIS Z3101-76 standard. GB/T4675.5-1984 was voided in 2005, and GB 2654-1981 was revised twice in 1989 and 2008, the current effective standard is GB/T2654-2008/ISO 9015-1:2001 "weld joint hardness test method (HARDNESS TEST methods on welded joints)". Currently, direct test measurements are still being used for the vickers hardness of welded joints of carbon steel. The method for directly measuring the Vickers hardness of the welding joint has relevant national and international standards, however, the evaluation method is too single, and the test period cost is high. The Vickers hardness measurement method needs to prepare a sample and perform a pressurizing test, can damage the integrity of a welded structure, and has the defects of complicated process and high test cost. For example, the surface of the Vickers hardness sample should be smooth and flat, cannot have oxide skin and impurities, and cannot have greasy dirt. In general, the surface roughness parameter Ra of the Vickers hardness sample is not more than 0.40 μm, the small-load Vickers hardness sample is not more than 0.20 μm, and the micro Vickers hardness sample is not more than 0.10 μm. (μm is a unit of the surface roughness parameter Ra.) Disclosure of Invention The invention aims at the technical problems that the current measuring method of the Vickers hardness in the prior art needs to prepare a sample and carry out a pressurizing test, the integrity of a welding structure can be damaged, the process is complicated and the testing cost is high. The invention provides a Vickers hardness evaluation method of a steel welding joint for a ship, which comprises the following steps of: S1, obtaining a thermal cycle curve of a welded joint of marine steel, and discretizing the thermal cycle curve to obtain a temperature curve; s2, inputting chemical components related to the marine steel, and evaluating the key temperature of the solid-state phase transition of the metal; s3, calculating the percentage of each microstructure component which can currently participate in the solid-state phase transformation of the metal; S4, calculating transient microstructure changes of different temperature change regions in the whole process from temperature rise to temperature reduction in the welding process according to the time step of discretization in the step S1, so as to obtain welding microstructure change models under different welding conditions; And S5, obtaining the current welding condition, matching with the welding microstructure change model to obtain the microstructure volume fraction ratio cooled to the room temperature, and carrying out weighted summation calculat